Impact: fix boot crash if the kernel is built with certain GCC versions
GCC has a bug with __weak alias functions: if the functions are in
the same compilation unit as their call site, GCC can decide to
inline them - and thus rob the linker of the opportunity to override
the weak alias with the real thing.
This can lead to the boot crash reported by Kamalesh Babulal:
ACPI: Core revision 20080926
Setting APIC routing to flat
BUG: unable to handle kernel NULL pointer dereference at
0000000000000000
IP: [<ffffffff8021f9a8>] add_pin_to_irq_cpu+0x14/0x74
PGD 0
Oops: 0000 [#1] SMP
[...]
So move the arch_init_chip_data() function from handle.c to manage.c.
Reported-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-next: (25 commits)
allow stripping of generated symbols under CONFIG_KALLSYMS_ALL
kbuild: strip generated symbols from *.ko
kbuild: simplify use of genksyms
kernel-doc: check for extra kernel-doc notations
kbuild: add headerdep used to detect inclusion cycles in header files
kbuild: fix string equality testing in tags.sh
kbuild: fix make tags/cscope
kbuild: fix make incompatibility
kbuild: remove TAR_IGNORE
setlocalversion: add git-svn support
setlocalversion: print correct subversion revision
scripts: improve the decodecode script
scripts/package: allow custom options to rpm
genksyms: allow to ignore symbol checksum changes
genksyms: track symbol checksum changes
tags and cscope support really belongs in a shell script
kconfig: fix options to check-lxdialog.sh
kbuild: gen_init_cpio expands shell variables in file names
remove bashisms from scripts/extract-ikconfig
kbuild: teach mkmakfile to be silent
...
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (241 commits)
sched, trace: update trace_sched_wakeup()
tracing/ftrace: don't trace on early stage of a secondary cpu boot, v3
Revert "x86: disable X86_PTRACE_BTS"
ring-buffer: prevent false positive warning
ring-buffer: fix dangling commit race
ftrace: enable format arguments checking
x86, bts: memory accounting
x86, bts: add fork and exit handling
ftrace: introduce tracing_reset_online_cpus() helper
tracing: fix warnings in kernel/trace/trace_sched_switch.c
tracing: fix warning in kernel/trace/trace.c
tracing/ring-buffer: remove unused ring_buffer size
trace: fix task state printout
ftrace: add not to regex on filtering functions
trace: better use of stack_trace_enabled for boot up code
trace: add a way to enable or disable the stack tracer
x86: entry_64 - introduce FTRACE_ frame macro v2
tracing/ftrace: add the printk-msg-only option
tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()
x86, bts: correctly report invalid bts records
...
Fixed up trivial conflict in scripts/recordmcount.pl due to SH bits
being already partly merged by the SH merge.
Impact: fix hang
Suresh report his two sockets system only works with SPARSE_IRQ enable
it turns out we miss the setting desc->irq
so provide early_irq_init() even !SPARSE_IRQ to set desc->irq
Reported-by: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add lockdep annotation to legacy IRQ descs
Warnings resulting out of this were not seen in practice, but it's prudent
to initialize the legacy descriptors to the lock class as well, symmetric
to how we do it with other descriptors.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix panic on null pointer with sparseirq
Some GCC versions seem to inline the weak global function,
when that function is empty.
Work it around, by making the functions return a (dummy) integer.
Signed-off-by: Yinghai <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
init_one_irq_desc() does not initialize the desc->lock properly -
you cannot init a lock by memcpying some other lock on it.
This happens to work right now (because irq_desc_init is never in use),
but it's a dangerous construct nevertheless, so fix it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: reduce printk noise
There were a couple of leftover KERN_DEBUG debugging printks, remove
them. Also clarify an error message.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
cpu_coregroup_map returned a cpumask_t: it's going away.
(Note, the sched part of this patch won't apply meaningfully to the
sched tree, but I'm posting it to show the goal).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ingo Molnar <mingo@redhat.com>
Impact: clean up
We already have a weak copy of this function in init/main.c
Signed-off-by: Yinghai <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
all for_each_irq_desc() usage point have !desc check.
then its check can move into for_each_irq_desc() macro.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
before CONFIG_SPARSE_IRQ age, for_each_irq_desc() sat in irqnr.h and
could be called from generic code.
CONFIG_SPARSE_IRQ breaks this assumption, but SPARSE_IRQ version
for_each_irq_desc() also can move into irqnr.h easily.
Also, this patch unifies CONFIG_SPARSE_IRQ and !CONFIG_SPARSE_IRQ
for_each_irq_desc().
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
<linux/irq.h> can be removed and should be, because:
- hrtimer doesn't use any irq feature.
- <linux/irq.h> shouldn't be include from generic code.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend the wakeup tracepoint with the info whether the wakeup was real
Add the information needed to distinguish 'real' wakeups from 'false'
wakeups.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix
Some architectures have not implemented save_stack_trace_tsk() yet:
fs/built-in.o: In function `proc_pid_stack':
base.c:(.text+0x3f140): undefined reference to `save_stack_trace_tsk'
So warn about that if the facility is used.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix
Some old architectures still do not use kernel/Kconfig.preempt, so the
moving of the RCU options there broke their build:
In file included from /home/mingo/tip/include/linux/sem.h:81,
from /home/mingo/tip/include/linux/sched.h:69,
from /home/mingo/tip/arch/alpha/kernel/asm-offsets.c:9:
/home/mingo/tip/include/linux/rcupdate.h:62:2: error: #error "Unknown RCU implementation specified to kernel configuration"
Move these options back to init/Kconfig, which every architecture
includes.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If cgroup_get_rootdir() failed, free_cg_links() will be called in the
failure path, but tmp_cg_links hasn't been initialized at that time.
I introduced this bug in the 2.6.27 merge window.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Andrew Morton reported:
> kernel/sched.c: In function 'schedule':
> kernel/sched.c:3679: warning: 'active_balance' may be used uninitialized in this function
>
> This warning is correct - the code is buggy.
In sched.c load_balance_newidle, there's real potential use of
uninitialised variable - fix it.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: eliminate false WARN_ON message
If an interrupt goes off after the setting of the local variable
tail_page and before incrementing the write index of that page,
the interrupt could push the commit forward to the next page.
Later a check is made to see if interrupts pushed the buffer around
the entire ring buffer by comparing the next page to the last commited
page. This can produce a false positive if the interrupt had pushed
the commit page forward as stated above.
Thanks to Jiaying Zhang for finding this race.
Reported-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix stuck trace-buffers
If an interrupt comes in during the rb_set_commit_to_write and
pushes the tail page forward just at the right time, the commit
updates will miss the adding of the interrupt data. This will
cause the commit pointer to cease from moving forward.
Thanks to Jiaying Zhang for finding this race.
Reported-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Prevent kernel crash with posix timer clockid CLOCK_MONOTONIC_RAW
commit 2d42244ae7 (clocksource:
introduce CLOCK_MONOTONIC_RAW) introduced a new clockid, which is only
available to read out the raw not NTP adjusted system time.
The above commit did not prevent that a posix timer can be created
with that clockid. The timer_create() syscall succeeds and initializes
the timer to a non existing hrtimer base. When the timer is deleted
either by timer_delete() or by the exit() cleanup the kernel crashes.
Prevent the creation of timers for CLOCK_MONOTONIC_RAW by setting the
posix clock function to no_timer_create which returns an error code.
Reported-and-tested-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: introduce new ptrace facility
Add arch_ptrace_untrace() function that is called when the tracer
detaches (either voluntarily or when the tracing task dies);
ptrace_disable() is only called on a voluntary detach.
Add ptrace_fork() and arch_ptrace_fork(). They are called when a
traced task is forked.
Clear DS and BTS related fields on fork.
Release DS resources and reclaim memory in ptrace_untrace(). This
releases resources already when the tracing task dies. We used to do
that when the traced task dies.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: reduce kconfig variable scope and clean up
Bartlomiej pointed out that the config dependencies and comments are not right.
update it depend to NUMA, and fix some comments
Reported-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix truncated recursion bug message printout
When recursion_bug is true, kernel discards original message because printk_buf
contains recursion_bug_msg with NULL terminator. The sizeof(recursion_bug_msg)
makes this, use strlen() to get correct length without NULL terminator.
Reported-by: Toshikazu Nakayama <nakayama.ts@ncos.nec.co.jp>
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Building upon parts of the module stripping patch, this patch
introduces similar stripping for vmlinux when CONFIG_KALLSYMS_ALL=y.
Using CONFIG_KALLSYMS_STRIP_GENERATED reduces the overhead of
CONFIG_KALLSYMS_ALL from 245k/310k to 65k/80k for the (i386/x86-64)
kernels I tested with.
The patch also does away with the need to special case the kallsyms-
internal symbols by making them available even in the first linking
stage.
While it is a generated file, the patch includes the changes to
scripts/genksyms/keywords.c_shipped, as I'm unsure what the procedure
here is.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Impact: cleanup
This patch factors out common code from multiple tracers into a
tracing_reset_online_cpus() function and converts the tracers to use it.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix cpumask conversion bug
this warning:
kernel/sched.c: In function ‘find_busiest_group’:
kernel/sched.c:3429: warning: passing argument 1 of ‘__first_cpu’ from incompatible pointer type
shows that we forgot to convert a new patch to the new cpumask APIs.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: tweak task balancing to save power more agressively
Active load balancing is a process by which migration thread
is woken up on the target CPU in order to pull current
running task on another package into this newly idle
package.
This method is already in use with normal load_balance(),
this patch introduces this method to new idle cpus when
sched_mc is set to POWERSAVINGS_BALANCE_WAKEUP.
This logic provides effective consolidation of short running
daemon jobs in a almost idle system
The side effect of this patch may be ping-ponging of tasks
if the system is moderately utilised. May need to adjust the
iterations before triggering.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: tweak task wakeup to save power more agressively
Preferred wakeup cpu (from a semi idle package) has been
nominated in find_busiest_group() in the previous patch. Use
this information in sched_mc_preferred_wakeup_cpu in function
wake_idle() to bias task wakeups if the following conditions
are satisfied:
- The present cpu that is trying to wakeup the process is
idle and waking the target process on this cpu will
potentially wakeup a completely idle package
- The previous cpu on which the target process ran is
also idle and hence selecting the previous cpu may
wakeup a semi idle cpu package
- The task being woken up is allowed to run in the
nominated cpu (cpu affinity and restrictions)
Basically if both the current cpu and the previous cpu on
which the task ran is idle, select the nominated cpu from semi
idle cpu package for running the new task that is waking up.
Cache hotness is considered since the actual biasing happens
in wake_idle() only if the application is cache cold.
This technique will effectively move short running bursty jobs in
a mostly idle system.
Wakeup biasing for power savings gets automatically disabled if
system utilisation increases due to the fact that the probability
of finding both this_cpu and prev_cpu idle decreases.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend load-balancing code (no change in behavior yet)
When the system utilisation is low and more cpus are idle,
then the process waking up from sleep should prefer to
wakeup an idle cpu from semi-idle cpu package (multi core
package) rather than a completely idle cpu package which
would waste power.
Use the sched_mc balance logic in find_busiest_group() to
nominate a preferred wakeup cpu.
This info can be stored in appropriate sched_domain, but
updating this info in all copies of sched_domain is not
practical. Hence this information is stored in root_domain
struct which is one copy per partitioned sched domain.
The root_domain can be accessed from each cpu's runqueue
and there is one copy per partitioned sched domain.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: change load-balancing direction to match that of irqbalanced
Just in case two groups have identical load, prefer to move load to lower
logical cpu number rather than the present logic of moving to higher logical
number.
find_busiest_group() tries to look for a group_leader that has spare capacity
to take more tasks and freeup an appropriate least loaded group. Just in case
there is a tie and the load is equal, then the group with higher logical number
is favoured. This conflicts with user space irqbalance daemon that will move
interrupts to lower logical number if the system utilisation is very low.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend range of /sys/devices/system/cpu/sched_mc_power_savings
Currently the sched_mc/smt_power_savings variable is a boolean,
which either enables or disables topology based power savings.
This patch extends the behaviour of the variable from boolean to
multivalued, such that based on the value, we decide how
aggressively do we want to perform powersavings balance at
appropriate sched domain based on topology.
Variable levels of power saving tunable would benefit end user to
match the required level of power savings vs performance
trade-off depending on the system configuration and workloads.
This version makes the sched_mc_power_savings global variable to
take more values (0,1,2). Later versions can have a single
tunable called sched_power_savings instead of
sched_{mc,smt}_power_savings.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Some apparently left over cruft code was complicating the fault logic:
Testing if uval != -EFAULT doesn't have any meaning, get_user() sets ret
to either 0 or -EFAULT, there's no need to compare uval, especially not
against EFAULT which it will never be. This patch removes the superfluous
test and clarifies the comment blocks.
Build and boot tested on an 8way x86_64 system.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
these warnings:
kernel/trace/trace_sched_switch.c: In function ‘tracing_sched_register’:
kernel/trace/trace_sched_switch.c:96: warning: passing argument 1 of ‘register_trace_sched_wakeup_new’ from incompatible pointer type
kernel/trace/trace_sched_switch.c:112: warning: passing argument 1 of ‘unregister_trace_sched_wakeup_new’ from incompatible pointer type
kernel/trace/trace_sched_switch.c: In function ‘tracing_sched_unregister’:
kernel/trace/trace_sched_switch.c:121: warning: passing argument 1 of ‘unregister_trace_sched_wakeup_new’ from incompatible pointer type
Trigger because sched_wakeup_new tracepoints need the same trace
signature as sched_wakeup - which was changed recently.
Fix it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
this warning:
kernel/trace/trace.c: In function ‘print_lat_fmt’:
kernel/trace/trace.c:1826: warning: unused variable ‘state’
Triggers because 'state' has become unused - remove it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
this warning:
kernel/hrtimer.c: In function ‘hrtimer_cpu_notify’:
kernel/hrtimer.c:1574: warning: unused variable ‘dcpu’
is caused because 'dcpu' is only used in the CONFIG_HOTPLUG_CPU case.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch fixes a long-standing performance bug in classic RCU that
results in massive internal-to-RCU lock contention on systems with
more than a few hundred CPUs. Although this patch creates a separate
flavor of RCU for ease of review and patch maintenance, it is intended
to replace classic RCU.
This patch still handles stress better than does mainline, so I am still
calling it ready for inclusion. This patch is against the -tip tree.
Nevertheless, experience on an actual 1000+ CPU machine would still be
most welcome.
Most of the changes noted below were found while creating an rcutiny
(which should permit ejecting the current rcuclassic) and while doing
detailed line-by-line documentation.
Updates from v9 (http://lkml.org/lkml/2008/12/2/334):
o Fixes from remainder of line-by-line code walkthrough,
including comment spelling, initialization, undesirable
narrowing due to type conversion, removing redundant memory
barriers, removing redundant local-variable initialization,
and removing redundant local variables.
I do not believe that any of these fixes address the CPU-hotplug
issues that Andi Kleen was seeing, but please do give it a whirl
in case the machine is smarter than I am.
A writeup from the walkthrough may be found at the following
URL, in case you are suffering from terminal insomnia or
masochism:
http://www.kernel.org/pub/linux/kernel/people/paulmck/tmp/rcutree-walkthrough.2008.12.16a.pdf
o Made rcutree tracing use seq_file, as suggested some time
ago by Lai Jiangshan.
o Added a .csv variant of the rcudata debugfs trace file, to allow
people having thousands of CPUs to drop the data into
a spreadsheet. Tested with oocalc and gnumeric. Updated
documentation to suit.
Updates from v8 (http://lkml.org/lkml/2008/11/15/139):
o Fix a theoretical race between grace-period initialization and
force_quiescent_state() that could occur if more than three
jiffies were required to carry out the grace-period
initialization. Which it might, if you had enough CPUs.
o Apply Ingo's printk-standardization patch.
o Substitute local variables for repeated accesses to global
variables.
o Fix comment misspellings and redundant (but harmless) increments
of ->n_rcu_pending (this latter after having explicitly added it).
o Apply checkpatch fixes.
Updates from v7 (http://lkml.org/lkml/2008/10/10/291):
o Fixed a number of problems noted by Gautham Shenoy, including
the cpu-stall-detection bug that he was having difficulty
convincing me was real. ;-)
o Changed cpu-stall detection to wait for ten seconds rather than
three in order to reduce false positive, as suggested by Ingo
Molnar.
o Produced a design document (http://lwn.net/Articles/305782/).
The act of writing this document uncovered a number of both
theoretical and "here and now" bugs as noted below.
o Fix dynticks_nesting accounting confusion, simplify WARN_ON()
condition, fix kerneldoc comments, and add memory barriers
in dynticks interface functions.
o Add more data to tracing.
o Remove unused "rcu_barrier" field from rcu_data structure.
o Count calls to rcu_pending() from scheduling-clock interrupt
to use as a surrogate timebase should jiffies stop counting.
o Fix a theoretical race between force_quiescent_state() and
grace-period initialization. Yes, initialization does have to
go on for some jiffies for this race to occur, but given enough
CPUs...
Updates from v6 (http://lkml.org/lkml/2008/9/23/448):
o Fix a number of checkpatch.pl complaints.
o Apply review comments from Ingo Molnar and Lai Jiangshan
on the stall-detection code.
o Fix several bugs in !CONFIG_SMP builds.
o Fix a misspelled config-parameter name so that RCU now announces
at boot time if stall detection is configured.
o Run tests on numerous combinations of configurations parameters,
which after the fixes above, now build and run correctly.
Updates from v5 (http://lkml.org/lkml/2008/9/15/92, bad subject line):
o Fix a compiler error in the !CONFIG_FANOUT_EXACT case (blew a
changeset some time ago, and finally got around to retesting
this option).
o Fix some tracing bugs in rcupreempt that caused incorrect
totals to be printed.
o I now test with a more brutal random-selection online/offline
script (attached). Probably more brutal than it needs to be
on the people reading it as well, but so it goes.
o A number of optimizations and usability improvements:
o Make rcu_pending() ignore the grace-period timeout when
there is no grace period in progress.
o Make force_quiescent_state() avoid going for a global
lock in the case where there is no grace period in
progress.
o Rearrange struct fields to improve struct layout.
o Make call_rcu() initiate a grace period if RCU was
idle, rather than waiting for the next scheduling
clock interrupt.
o Invoke rcu_irq_enter() and rcu_irq_exit() only when
idle, as suggested by Andi Kleen. I still don't
completely trust this change, and might back it out.
o Make CONFIG_RCU_TRACE be the single config variable
manipulated for all forms of RCU, instead of the prior
confusion.
o Document tracing files and formats for both rcupreempt
and rcutree.
Updates from v4 for those missing v5 given its bad subject line:
o Separated dynticks interface so that NMIs and irqs call separate
functions, greatly simplifying it. In particular, this code
no longer requires a proof of correctness. ;-)
o Separated dynticks state out into its own per-CPU structure,
avoiding the duplicated accounting.
o The case where a dynticks-idle CPU runs an irq handler that
invokes call_rcu() is now correctly handled, forcing that CPU
out of dynticks-idle mode.
o Review comments have been applied (thank you all!!!).
For but one example, fixed the dynticks-ordering issue that
Manfred pointed out, saving me much debugging. ;-)
o Adjusted rcuclassic and rcupreempt to handle dynticks changes.
Attached is an updated patch to Classic RCU that applies a hierarchy,
greatly reducing the contention on the top-level lock for large machines.
This passes 10-hour concurrent rcutorture and online-offline testing on
128-CPU ppc64 without dynticks enabled, and exposes some timekeeping
bugs in presence of dynticks (exciting working on a system where
"sleep 1" hangs until interrupted...), which were fixed in the
2.6.27 kernel. It is getting more reliable than mainline by some
measures, so the next version will be against -tip for inclusion.
See also Manfred Spraul's recent patches (or his earlier work from
2004 at http://marc.info/?l=linux-kernel&m=108546384711797&w=2).
We will converge onto a common patch in the fullness of time, but are
currently exploring different regions of the design space. That said,
I have already gratefully stolen quite a few of Manfred's ideas.
This patch provides CONFIG_RCU_FANOUT, which controls the bushiness
of the RCU hierarchy. Defaults to 32 on 32-bit machines and 64 on
64-bit machines. If CONFIG_NR_CPUS is less than CONFIG_RCU_FANOUT,
there is no hierarchy. By default, the RCU initialization code will
adjust CONFIG_RCU_FANOUT to balance the hierarchy, so strongly NUMA
architectures may choose to set CONFIG_RCU_FANOUT_EXACT to disable
this balancing, allowing the hierarchy to be exactly aligned to the
underlying hardware. Up to two levels of hierarchy are permitted
(in addition to the root node), allowing up to 16,384 CPUs on 32-bit
systems and up to 262,144 CPUs on 64-bit systems. I just know that I
am going to regret saying this, but this seems more than sufficient
for the foreseeable future. (Some architectures might wish to set
CONFIG_RCU_FANOUT=4, which would limit such architectures to 64 CPUs.
If this becomes a real problem, additional levels can be added, but I
doubt that it will make a significant difference on real hardware.)
In the common case, a given CPU will manipulate its private rcu_data
structure and the rcu_node structure that it shares with its immediate
neighbors. This can reduce both lock and memory contention by multiple
orders of magnitude, which should eliminate the need for the strange
manipulations that are reported to be required when running Linux on
very large systems.
Some shortcomings:
o More bugs will probably surface as a result of an ongoing
line-by-line code inspection.
Patches will be provided as required.
o There are probably hangs, rcutorture failures, &c. Seems
quite stable on a 128-CPU machine, but that is kind of small
compared to 4096 CPUs. However, seems to do better than
mainline.
Patches will be provided as required.
o The memory footprint of this version is several KB larger
than rcuclassic.
A separate UP-only rcutiny patch will be provided, which will
reduce the memory footprint significantly, even compared
to the old rcuclassic. One such patch passes light testing,
and has a memory footprint smaller even than rcuclassic.
Initial reaction from various embedded guys was "it is not
worth it", so am putting it aside.
Credits:
o Manfred Spraul for ideas, review comments, and bugs spotted,
as well as some good friendly competition. ;-)
o Josh Triplett, Ingo Molnar, Peter Zijlstra, Mathieu Desnoyers,
Lai Jiangshan, Andi Kleen, Andy Whitcroft, and Andrew Morton
for reviews and comments.
o Thomas Gleixner for much-needed help with some timer issues
(see patches below).
o Jon M. Tollefson, Tim Pepper, Andrew Theurer, Jose R. Santos,
Andy Whitcroft, Darrick Wong, Nishanth Aravamudan, Anton
Blanchard, Dave Kleikamp, and Nathan Lynch for keeping machines
alive despite my heavy abuse^Wtesting.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: simplify code
commit "08678b0: generic: sparse irqs: use irq_desc() [...]" introduced
the irq_desc_lock_class variable.
But it is used only if CONFIG_SPARSE_IRQ=Y or CONFIG_TRACE_IRQFLAGS=Y.
Otherwise, following warnings happen:
CC kernel/irq/handle.o
kernel/irq/handle.c:26: warning: 'irq_desc_lock_class' defined but not used
Actually, current early_init_irq_lock_class has a bit strange and messy ifdef.
In addition, it is not valueable.
1. this function is protected by !CONFIG_SPARSE_IRQ, but that is not necessary.
if CONFIG_SPARSE_IRQ=Y, desc of all irq number are initialized by NULL
at first - then this function calling is safe.
2. this function protected by CONFIG_TRACE_IRQFLAGS too. but it is not
necessary either, because lockdep_set_class() doesn't have bad side
effect even if CONFIG_TRACE_IRQFLAGS=n.
This patch bloat kernel size a bit on CONFIG_TRACE_IRQFLAGS=n and
CONFIG_SPARSE_IRQ=Y - but that's ok. early_init_irq_lock_class() is not
a fastpatch at all.
To avoid messy ifdefs is more important than a few bytes diet.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: simplify code
When we turn on CONFIG_SCHEDSTATS, per-task cpu runtime is accumulated
twice. Once in task->se.sum_exec_runtime and once in sched_info.cpu_time.
These two stats are exactly the same.
Given that task->se.sum_exec_runtime is always accumulated by the core
scheduler, sched_info can reuse that data instead of duplicate the accounting.
Signed-off-by: Ken Chen <kenchen@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: remove dead code
struct ring_buffer.size is not set after ring_buffer is initialized
or resized. it is always 0.
we can use "buffer->pages * PAGE_SIZE" to get ring_buffer's size
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix occasionally incorrect trace output
The tracing code has interesting varieties of printing out task state.
Unfortunalely only one of the instances is correct as it copies the
code from sched.c:sched_show_task(). The others are plain wrong as
they treatthe bitfield as an integer offset into the character
array. Also the size check of the character array is wrong as it
includes the trailing \0.
Use a common state decoder inline which does the Right Thing.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: enhancement
Ingo Molnar has asked about a way to remove items from the filter
lists. Currently, you can only add or replace items. The way
items are added to the list is through opening one of the list
files (set_ftrace_filter or set_ftrace_notrace) via append.
If the file is opened for truncate, the list is cleared.
echo spin_lock > /debug/tracing/set_ftrace_filter
The above will replace the list with only spin_lock
echo spin_lock >> /debug/tracing/set_ftrace_filter
The above will add spin_lock to the list.
Now this patch adds:
echo '!spin_lock' >> /debug/tracing/set_ftrace_filter
This will remove spin_lock from the list.
The limited glob features of these lists also can be notted.
echo '!spin_*' >> /debug/tracing/set_ftrace_filter
This will remove all functions that start with 'spin_'
Note:
echo '!spin_*' > /debug/tracing/set_ftrace_filter
will simply clear out the list (notice the '>' instead of '>>')
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
Andrew Morton suggested to use the stack_tracer_enabled variable
to decide whether or not to start stack tracing on bootup.
This lets us remove the start_stack_trace variable.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: enhancement to stack tracer
The stack tracer currently is either on when configured in or
off when it is not. It can not be disabled when it is configured on.
(besides disabling the function tracer that it uses)
This patch adds a way to enable or disable the stack tracer at
run time. It defaults off on bootup, but a kernel parameter 'stacktrace'
has been added to enable it on bootup.
A new sysctl has been added "kernel.stack_tracer_enabled" to let
the user enable or disable the stack tracer at run time.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: simplify code
I've tripped over the naming of this field a couple times.
The futex_q uses a "waiters" list to represent a single blocked task and
then calles wake_up_all().
This can lead to confusion in trying to understand the intent of the code,
which is to have a single futex_q for every task waiting on a futex.
This patch corrects the problem, using a single pointer to the waiting
task, and an appropriate call to wake_up, rather than wake_up_all.
Compile and boot tested on an 8way x86_64 machine.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: display ftrace_printk messages "as is"
By default, ftrace_printk() messages find their output with some other
informations like pid, caller, ...
Sometimes a developer just want to have the ftrace_printk left "as is", without
other information.
This is done by providing a default-off option called printk-msg-only.
To enable it, just do `echo printk-msg-only > /debugfs/tracing/trace_options`
Before the patch:
<...>-2739 [000] 145.692153: __might_sleep: I'm an ftrace_printk msg in __might_sleep
<...>-2739 [000] 145.692155: __might_sleep: I'm another ftrace_printk msg in __might_sleep
After the patch and the printk-msg-only option enabled:
I'm an ftrace_printk msg in __might_sleep
I'm another ftrace_printk msg in __might_sleep
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: prevent a trace recursion
After some tests with function graph tracer under x86-32, I saw some recursions
caused by ring_buffer_time_stamp() that calls preempt_enable_no_notrace() which
calls preempt_schedule() which is traced itself.
This patch re-enables preemption without rescheduling.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: improve NUMA handling by migrating irq_desc on smp_affinity changes
if CONFIG_NUMA_MIGRATE_IRQ_DESC is set:
- make irq_desc to go with affinity aka irq_desc moving etc
- call move_irq_desc in irq_complete_move()
- legacy irq_desc is not moved, because they are allocated via static array
for logical apic mode, need to add move_desc_in_progress_in_same_domain,
otherwise it will not be moved ==> also could need two phases to get
irq_desc moved.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix very rare reboot hang
Because rcutorture ignored all signals, it does not terminate in
response to the signals sent at shutdown time. This can cause strange
failures due to its continuing to make use of kernel function too late
in the shutdown sequence. This patch therefore adds a shutdown notifier
to rcutorture, causing it to shut down in response to a reboot or an
orderly shutdown.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: reduce false positives in iomem_map_sanity_check()
Some drivers (vesafb) only map/reserve a portion of a resource.
If then some other driver comes in and maps the whole resource,
the current code WARN_ON's. This is not the intent of the checks
in iomem_map_sanity_check(); rather these checks want to
warn when crossing *hardware* resources only.
This patch skips BUSY resources as suggested by Linus.
Note: having two drivers talk to the same hardware at the same
time is obviously not optimal behavior, but that's a separate story.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix potential of rare crash
for_each_leaf_rt_rq() walks an RCU protected list (rq->leaf_rt_rq_list),
but doesn't use list_for_each_entry_rcu(). Fix this.
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch export per-cpu CPU cycle usage for a given cpuacct cgroup.
There is a need for a user space monitor daemon to track group CPU
usage on per-cpu base. It is also useful for monitoring CFS load
balancer behavior by tracking per CPU group usage.
Signed-off-by: Ken Chen <kenchen@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: micro-optimize the code on 64-bit architectures
In the thread regarding to 'export percpu cpuacct cgroup stats'
http://lkml.org/lkml/2008/12/7/13
akpm pointed out that current cpuacct code is inefficient. This patch
refactoring the following:
* make cpu_rq locking only on 32-bit
* change iterator to each_present_cpu instead of each_possible_cpu to
make it hotplug friendly.
It's a bit of code churn, but I was rewarded with 160 byte code size saving
on x86-64 arch and zero code size change on i386.
Signed-off-by: Ken Chen <kenchen@google.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: micro-optimization
Skip the hard work when there is none.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: sharpen the wakeup-granularity to always be against current scheduler time
It was possible to do the preemption check against an old time stamp.
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When a cgroup is removed, it's unlinked from its parent's children list,
but not actually freed until the last dentry on it is released (at which
point cgrp->root->number_of_cgroups is decremented).
Currently rebind_subsystems checks for the top cgroup's child list being
empty in order to rebind subsystems into or out of a hierarchy - this can
result in the set of subsystems bound to a hierarchy being
removed-but-not-freed cgroup.
The simplest fix for this is to forbid remounts that change the set of
subsystems on a hierarchy that has removed-but-not-freed cgroups. This
bug can be reproduced via:
mkdir /mnt/cg
mount -t cgroup -o ns,freezer cgroup /mnt/cg
mkdir /mnt/cg/foo
sleep 1h < /mnt/cg/foo &
rmdir /mnt/cg/foo
mount -t cgroup -o remount,ns,devices,freezer cgroup /mnt/cg
kill $!
Though the above will cause oops in -mm only but not mainline, but the bug
can cause memory leak in mainline (and even oops)
Signed-off-by: Paul Menage <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 5b7dba4ff8, which
caused a regression in hibernate, reported by and bisected by Fabio
Comolli.
This revert fixes
http://bugzilla.kernel.org/show_bug.cgi?id=12155http://bugzilla.kernel.org/show_bug.cgi?id=12149
Bisected-by: Fabio Comolli <fabio.comolli@gmail.com>
Requested-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: change calling convention of existing clock_event APIs
struct clock_event_timer's cpumask field gets changed to take pointer,
as does the ->broadcast function.
Another single-patch change. For safety, we BUG_ON() in
clockevents_register_device() if it's not set.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Impact: change existing irq_chip API
Not much point with gentle transition here: the struct irq_chip's
setaffinity method signature needs to change.
Fortunately, not widely used code, but hits a few architectures.
Note: In irq_select_affinity() I save a temporary in by mangling
irq_desc[irq].affinity directly. Ingo, does this break anything?
(Folded in fix from KOSAKI Motohiro)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Grant Grundler <grundler@parisc-linux.org>
Acked-by: Ingo Molnar <mingo@redhat.com>
Cc: ralf@linux-mips.org
Cc: grundler@parisc-linux.org
Cc: jeremy@xensource.com
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Impact: change calling convention of existing cpumask APIs
Most cpumask functions started with cpus_: these have been replaced by
cpumask_ ones which take struct cpumask pointers as expected.
These four functions don't have good replacement names; fortunately
they're rarely used, so we just change them over.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: paulus@samba.org
Cc: mingo@redhat.com
Cc: tony.luck@intel.com
Cc: ralf@linux-mips.org
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: cl@linux-foundation.org
Cc: srostedt@redhat.com
Impact: cleanup
Each SMP arch defines these themselves. Move them to a central
location.
Twists:
1) Some archs (m32, parisc, s390) set possible_map to all 1, so we add a
CONFIG_INIT_ALL_POSSIBLE for this rather than break them.
2) mips and sparc32 '#define cpu_possible_map phys_cpu_present_map'.
Those archs simply have phys_cpu_present_map replaced everywhere.
3) Alpha defined cpu_possible_map to cpu_present_map; this is tricky
so I just manipulate them both in sync.
4) IA64, cris and m32r have gratuitous 'extern cpumask_t cpu_possible_map'
declarations.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Grant Grundler <grundler@parisc-linux.org>
Tested-by: Tony Luck <tony.luck@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Mike Travis <travis@sgi.com>
Cc: ink@jurassic.park.msu.ru
Cc: rmk@arm.linux.org.uk
Cc: starvik@axis.com
Cc: tony.luck@intel.com
Cc: takata@linux-m32r.org
Cc: ralf@linux-mips.org
Cc: grundler@parisc-linux.org
Cc: paulus@samba.org
Cc: schwidefsky@de.ibm.com
Cc: lethal@linux-sh.org
Cc: wli@holomorphy.com
Cc: davem@davemloft.net
Cc: jdike@addtoit.com
Cc: mingo@redhat.com
Impact: clean up, speed up
->it_pid (was ->it_process) has also a special meaning: if it is NULL,
the timer is under deletion or it wasn't initialized yet. We can check
->it_signal != NULL instead, this way we can
- simplify sys_timer_create() a bit
- remove yet another check from lock_timer()
- move put_pid(->it_pid) into release_posix_timer() which
runs outside of ->it_lock
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Impact: restructure, clean up code
k_itimer holds the ref to the ->it_process until sys_timer_delete(). This
allows to pin up to RLIMIT_SIGPENDING dead task_struct's. Change the code
to use "struct pid *" instead.
The patch doesn't kill ->it_process, it places ->it_pid into the union.
->it_process is still used by do_cpu_nanosleep() as before. It would be
trivial to change the nanosleep code as well, but since it uses it_process
in a special way I think it is better to keep this field for grep.
The patch bloats the kernel by 104 bytes and it also adds the new pointer,
->it_signal, to k_itimer. It is used by lock_timer() to verify that the
found timer was not created by another process. It is not clear why do we
use the global database (and thus the global idr_lock) for posix timers.
We still need the signal_struct->posix_timers which contains all useable
timers, perhaps it is better to use some form of per-process array
instead.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In my device I get many interrupts from a high speed USB device in a very
short period of time. The system spends a lot of time reprogramming the
hardware timer which is in a slower timing domain as compared to the CPU.
This results in the CPU spending a huge amount of time waiting for the
timer posting to be done. All of this reprogramming is useless as the
wake up time has not changed.
As measured using ETM trace this drops my reprogramming penalty from
almost 60% CPU load down to 15% during high interrupt rate. I can send
traces to show this.
Suppress setting of duplicate timer event when timer already stopped.
Timer programming can be very costly and can result in long cpu stall/wait
times.
[akpm@linux-foundation.org: coding-style fixes]
[tglx@linutronix.de: move the check to the right place and avoid raising
the softirq for nothing]
Signed-off-by: Richard Woodruff <r-woodruff2@ti.com>
Cc: johnstul@us.ibm.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We merge the irq/sparseirq, x86/quirks and x86/reboot trees into the
cpus4096 tree because the io-apic changes in the sparseirq change
conflict with the cpumask changes in the cpumask tree, and we
want to resolve those.
arch_reinit_sched_domains() used to call arch_update_cpu_topology()
via arch_init_sched_domains(). This call got lost with
e761b77252 ("cpu hotplug, sched: Introduce
cpu_active_map and redo sched domain managment (take 2)".
So we might end up with outdated and missing cpus in the cpu core
maps (architecture used to call arch_reinit_sched_domains if cpu
topology changed).
This adds a call to arch_update_cpu_topology in partition_sched_domains
which gets called whenever scheduling domains get updated. Which is
what is supposed to happen when cpu topology changes.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change arch_update_cpu_topology so it returns 1 if the cpu topology changed
and 0 if it didn't change. This will be useful for the next patch which adds
a call to this function in partition_sched_domains.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The trace point only caught one of many places where a task changes cpu,
put it in the right place to we get all of them.
Change the signature while we're at it.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: restructure code, cleanup
Remove BTS bits from the hw-branch-tracer (renamed from bts-tracer) and
use the ds interface.
Signed-off-by: Markus Metzger <markut.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: remove false positive warning
After a cpu was taken down during cpu hotplug (read: disabled for interrupts)
it still might have pending softirqs. However take_cpu_down makes sure
that the idle task will run next instead of ksoftirqd on the taken down cpu.
The idle task will call tick_nohz_stop_sched_tick which might warn about
pending softirqs just before the cpu kills itself completely.
However the pending softirqs on the dead cpu aren't a problem because they
will be moved to an online cpu during CPU_DEAD handling.
So make sure we warn only for online cpus.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I added EXPORT_SYMBOL_GPLs for all functions part of the API
(ring_buffer.h). This is required since oprofile is using the ring
buffer and the compilation as modules would fail otherwise.
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lee Schermerhorn noticed yesterday that I broke the mapping_writably_mapped
test in 2.6.7! Bad bad bug, good good find.
The i_mmap_writable count must be incremented for VM_SHARED (just as
i_writecount is for VM_DENYWRITE, but while holding the i_mmap_lock)
when dup_mmap() copies the vma for fork: it has its own more optimal
version of __vma_link_file(), and I missed this out. So the count
was later going down to 0 (dangerous) when one end unmapped, then
wrapping negative (inefficient) when the other end unmapped.
The only impact on x86 would have been that setting a mandatory lock on
a file which has at some time been opened O_RDWR and mapped MAP_SHARED
(but not necessarily PROT_WRITE) across a fork, might fail with -EAGAIN
when it should succeed, or succeed when it should fail.
But those architectures which rely on flush_dcache_page() to flush
userspace modifications back into the page before the kernel reads it,
may in some cases have skipped the flush after such a fork - though any
repetitive test will soon wrap the count negative, in which case it will
flush_dcache_page() unnecessarily.
Fix would be a two-liner, but mapping variable added, and comment moved.
Reported-by: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miles Lane tailing /sys files hit a BUG which Pekka Enberg has tracked
to my 966c8c12dc sprint_symbol(): use
less stack exposing a bug in slub's list_locations() -
kallsyms_lookup() writes a 0 to namebuf[KSYM_NAME_LEN-1], but that was
beyond the end of page provided.
The 100 slop which list_locations() allows at end of page looks roughly
enough for all the other stuff it might print after the symbol before
it checks again: break out KSYM_SYMBOL_LEN earlier than before.
Latencytop and ftrace and are using KSYM_NAME_LEN buffers where they
need KSYM_SYMBOL_LEN buffers, and vmallocinfo a 2*KSYM_NAME_LEN buffer
where it wants a KSYM_SYMBOL_LEN buffer: fix those before anyone copies
them.
[akpm@linux-foundation.org: ftrace.h needs module.h]
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc Miles Lane <miles.lane@gmail.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Running kmemtraced, which uses splice() on relayfs, causes a hard lock on
x86-64 SMP. As described by Tom Zanussi:
It looks like you hit the same problem as described here:
commit 8191ecd1d1
splice: fix infinite loop in generic_file_splice_read()
relay uses the same loop but it never got noticed or fixed.
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Tested-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: fix possible deadlock in CPU hot-remove path
This patch fixes a possible deadlock scenario in the CPU remove path.
migration_call grabs rq->lock, then wakes up everything on rq->migration_queue
with the lock held. Then one of the tasks on the migration queue ends up
calling tg_shares_up which then also tries to acquire the same rq->lock.
[c000000058eab2e0] c000000000502078 ._spin_lock_irqsave+0x98/0xf0
[c000000058eab370] c00000000008011c .tg_shares_up+0x10c/0x20c
[c000000058eab430] c00000000007867c .walk_tg_tree+0xc4/0xfc
[c000000058eab4d0] c0000000000840c8 .try_to_wake_up+0xb0/0x3c4
[c000000058eab590] c0000000000799a0 .__wake_up_common+0x6c/0xe0
[c000000058eab640] c00000000007ada4 .complete+0x54/0x80
[c000000058eab6e0] c000000000509fa8 .migration_call+0x5fc/0x6f8
[c000000058eab7c0] c000000000504074 .notifier_call_chain+0x68/0xe0
[c000000058eab860] c000000000506568 ._cpu_down+0x2b0/0x3f4
[c000000058eaba60] c000000000506750 .cpu_down+0xa4/0x108
[c000000058eabb10] c000000000507e54 .store_online+0x44/0xa8
[c000000058eabba0] c000000000396260 .sysdev_store+0x3c/0x50
[c000000058eabc10] c0000000001a39b8 .sysfs_write_file+0x124/0x18c
[c000000058eabcd0] c00000000013061c .vfs_write+0xd0/0x1bc
[c000000058eabd70] c0000000001308a4 .sys_write+0x68/0x114
[c000000058eabe30] c0000000000086b4 syscall_exit+0x0/0x40
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Delete excess kernel-doc notation in kernel/auditsc.c:
Warning(linux-2.6.27-git10//kernel/auditsc.c:1481): Excess function parameter or struct member 'tsk' description in 'audit_syscall_entry'
Warning(linux-2.6.27-git10//kernel/auditsc.c:1564): Excess function parameter or struct member 'tsk' description in 'audit_syscall_exit'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently audit=0 on the kernel command line does absolutely nothing.
Audit always loads and always uses its resources such as creating the
kernel netlink socket. This patch causes audit=0 to actually disable
audit. Audit will use no resources and starting the userspace auditd
daemon will not cause the kernel audit system to activate.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Documented the currently bogus state of support for CFS user groups with
user namespaces. In particular, all users in a user namespace should be
children of the user which created the user namespace. This is yet to
be implemented.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
> Ingo, this addition fixes the hotplug issue on my machine
And because we're all human...
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
this warning:
kernel/trace/trace.c: In function ‘trace_vprintk’:
kernel/trace/trace.c:3626: warning: ‘flags’ may be used uninitialized in this function
shows some confusion about irq_flags / flags use here. We already have
irq_flags so remove the extra flags variable.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix SD_BALANCE_NEWIDLEand broaden its use
load_balance_newidle() does not get called if SD_BALANCE_NEWIDLE is
set at higher level domain (3-CPU) and not in low level domain (2-MC).
pulled_task is initialised to -1 and checked for non-zero which is
always true if the lowest level sched_domain does not have
SD_BALANCE_NEWIDLE flag set.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Provide a way to pause the function graph tracer
As suggested by Steven Rostedt, the previous patch that prevented from
spinlock function tracing shouldn't use the raw_spinlock to fix it.
It's much better to follow lockdep with normal spinlock, so this patch
adds a new flag for each task to make the function graph tracer able
to be paused. We also can send an ftrace_printk whithout worrying of
the irrelevant traced spinlock during insertion.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Apply some suggestions of Steven Rostedt:
_turn tracing_selftest_running into a simple int (no need of an atomic_t)
_set it __read_mostly
_fix a comment style
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: trace more functions
When the function graph tracer is configured, three more files are not
traced to prevent only four functions to be traced. And this impacts the
normal function tracer too.
arch/x86/kernel/process_64/32.c:
I had crashes when I let this file traced. After some debugging, I saw
that the "current" task point was changed inside__swtich_to(), ie:
"write_pda(pcurrent, next_p);" inside process_64.c Since the tracer store
the original return address of the function inside current, we had
crashes. Only __switch_to() has to be excluded from tracing.
kernel/module.c and kernel/extable.c:
Because of a function used internally by the function graph tracer:
__kernel_text_address()
To let the other functions inside these files to be traced, this patch
introduces the __notrace_funcgraph function prefix which is __notrace if
function graph tracer is configured and nothing if not.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new feature
Problem on distro kernels: irq_desc[NR_IRQS] takes megabytes of RAM with
NR_CPUS set to large values. The goal is to be able to scale up to much
larger NR_IRQS value without impacting the (important) common case.
To solve this, we generalize irq_desc[NR_IRQS] to an (optional) array of
irq_desc pointers.
When CONFIG_SPARSE_IRQ=y is used, we use kzalloc_node to get irq_desc,
this also makes the IRQ descriptors NUMA-local (to the site that calls
request_irq()).
This gets rid of the irq_cfg[] static array on x86 as well: irq_cfg now
uses desc->chip_data for x86 to store irq_cfg.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: optimize the sched domains tree some more
The addition of SD_SERIALIZE flag added to SD_NODE_INIT prevented top level
dummy numa sched_domain to be properly degenerated on non-numa smp machine.
The reason is that in sd_parent_degenerate(), it found that the child and
parent does not have comon sched_domain flags due to SD_SERIALIZE. However,
for non-numa smp box, the top level is a dummy with a single sched_group.
Filter out SD_SERIALIZE if it is on non-numa machine to properly degenerate
top level node sched_domain. this will cut back some of the sd domain walk
in the load balancer code.
Signed-off-by: Ken Chen <kenchen@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: provide trace headers to explain a bit the output
This patch implements the print_headers callback for the function graph
tracer. These headers are output according to the current trace options.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
While ideally CLONE_NEWUSER will eventually require no
privilege, the required permission checks are currently
not there. As a result, CLONE_NEWUSER has the same effect
as a setuid(0)+setgroups(1,"0"). While we already require
CAP_SYS_ADMIN, requiring CAP_SETUID and CAP_SETGID seems
appropriate.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: James Morris <jmorris@namei.org>
(These two patches are in the next-unacked branch of
git://git.kernel.org/pub/scm/linux/kernel/git/sergeh/userns-2.6.
If they get some ACKs, then I hope to feed this into security-next.
After these two, I think we're ready to tackle userns+capabilities)
Fairsched creates a per-uid directory under /sys/kernel/uids/.
So when you clone(CLONE_NEWUSER), it tries to create
/sys/kernel/uids/0, which already exists, and you get back
-ENOMEM.
This was supposed to be fixed by sysfs tagging, but that
was postponed (ok, rejected until sysfs locking is fixed).
So, just as with network namespaces, we just don't create
those directories for user namespaces other than the init.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Impact: clean up
Using (struct pid *)-1 as the pointer for ftrace_swapper_pid is
a little confusing for others. This patch uses the address of the
actual init pid structure instead. This change is only for
clarity. It does not affect the code itself. Hopefully soon the
swapper tasks will all have their own pid structure and then
we can clean up the code a bit more.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
As suggested by Steven Rostedt, this patch provide a new macro
task_curr_ret_stack() to move the cpp conditionnal CONFIG into
the linux/ftrace.h headers.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix default empty traces on function-graph-tracer
The actual ftrace_trace_task() checks if ftrace_pid_trace is allocated
and return 1 if it is true.
If it is NULL, it will check the bit of pid tracing flag for the current
task (which are not set by default).
So by default, a task is not traced.
Actually all tasks should be traced by default and filter_by_pid when
ftrace_pid_trace is allocated.
The appropriate condition should be to return 1 if filter_by_pid is
set.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acke-dby: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix tracer selfstests false results
After setting a ftrace_printk somewhere in th kernel, I saw the
Function tracer selftest failing.
When a selftest occurs, the ring buffer is lurked to see if
some entries were inserted. But concurrent insertion such as
ftrace_printk could occured at the same time and could give
false positive or negative results.
This patch prevent prevent from TRACE_PRINT entries insertion
during selftests.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/bdev:
[PATCH] fix bogus argument of blkdev_put() in pktcdvd
[PATCH 2/2] documnt FMODE_ constants
[PATCH 1/2] kill FMODE_NDELAY_NOW
[PATCH] clean up blkdev_get a little bit
[PATCH] Fix block dev compat ioctl handling
[PATCH] kill obsolete temporary comment in swsusp_close()
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
time: catch xtime_nsec underflows and fix them
posix-cpu-timers: fix clock_gettime with CLOCK_PROCESS_CPUTIME_ID
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
check_hung_task(): unsigned sysctl_hung_task_warnings cannot be less than 0
documentation: local_ops fix on_each_cpu
Add a sysctl to tweak the RSS limit used to decide when to grow
the TSB for an address space.
In order to avoid expensive divides and multiplies only simply
positive and negative powers of two are supported.
The function computed takes the number of TSB translations that will
fit at one time in the TSB of a given size, and either adds or
subtracts a percentage of entries. This final value is the
RSS limit.
See tsb_size_to_rss_limit().
Signed-off-by: David S. Miller <davem@davemloft.net>
Impact: fix hrtimer locking (reported by lockdep) in the CPU hotplug case
This addition fixes the hotplug locking issue on my machine
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
it had been put there to mark the call of blkdev_put() that
needed proper argument propagated to it; later patch in the
same series had done just that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Handle the TRACE_PRINT entries from the function grapg tracer
and output them as a C comment just below the function that called
it, as if it was a comment inside this function.
Example with an ftrace_printk inside might_sleep() function:
void __might_sleep(char *file, int line)
{
static unsigned long prev_jiffy; /* ratelimiting */
ftrace_printk("Hi I'm a comment in might_sleep() :-)");
A chunk of a resulting trace:
0) | _reiserfs_free_block() {
0) | reiserfs_read_bitmap_block() {
0) | __bread() {
0) | __getblk() {
0) | __find_get_block() {
0) 0.698 us | mark_page_accessed();
0) 2.267 us | }
0) | __might_sleep() {
0) | /* Hi I'm a comment in might_sleep() :-) */
0) 1.321 us | }
0) 5.872 us | }
0) 7.313 us | }
0) 8.718 us | }
And this patch brings two minor fixes:
- The newline after a switch-out task has disappeared
- The "|" sign just before the cpu number on task-switch has been deleted.
0) 0.616 us | pick_next_task_rt();
0) 1.457 us | _spin_trylock();
0) 0.653 us | _spin_unlock();
0) 0.728 us | _spin_trylock();
0) 0.631 us | _spin_unlock();
0) 0.729 us | native_load_sp0();
0) 0.593 us | native_load_tls();
------------------------------------------
0) cat-2834 => migrati-3
------------------------------------------
0) | finish_task_switch() {
0) 0.841 us | _spin_unlock_irq();
0) 0.616 us | post_schedule_rt();
0) 3.882 us | }
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: introduce new lockdep API
Allow to change a held lock's class. Basically the same as the existing
code to change a subclass therefore reuse all that.
The XFS code will be able to use this to annotate their inode locking.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix a bug in function filter setting
when writing function to set_graph_function, we should check whether it
has existed in set_graph_function to avoid duplicating.
Signed-off-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new feature
This patch lets the swapper tasks of all CPUS be filtered by the
set_ftrace_pid file.
If '0' is echoed into this file, then all the idle tasks (aka swapper)
is flagged to be traced. This affects all CPU idle tasks.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up, extend PID filtering to PID namespaces
Eric Biederman suggested using the struct pid for filtering on
pids in the kernel. This patch is based off of a demonstration
of an implementation that Eric sent me in an email.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: New feature
This patch makes the changes to set_ftrace_pid apply to the function
graph tracer.
# echo $$ > /debugfs/tracing/set_ftrace_pid
# echo function_graph > /debugfs/tracing/current_tracer
Will cause only the current task to be traced. Note, the trace flags are
also inherited by child processes, so the children of the shell
will also be traced.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
Use the new task struct trace flags to determine if a process should be
traced or not.
Note: this moves the searching of the pid to the slow path of setting
the pid field. This needs to be converted to the pid name space.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds the file:
/debugfs/tracing/set_graph_function
which can be used along with the function graph tracer.
When this file is empty, the function graph tracer will act as
usual. When the file has a function in it, the function graph
tracer will only trace that function.
For example:
# echo blk_unplug > /debugfs/tracing/set_graph_function
# cat /debugfs/tracing/trace
[...]
------------------------------------------
| 2) make-19003 => kjournald-2219
------------------------------------------
2) | blk_unplug() {
2) | dm_unplug_all() {
2) | dm_get_table() {
2) 1.381 us | _read_lock();
2) 0.911 us | dm_table_get();
2) 1. 76 us | _read_unlock();
2) + 12.912 us | }
2) | dm_table_unplug_all() {
2) | blk_unplug() {
2) 0.778 us | generic_unplug_device();
2) 2.409 us | }
2) 5.992 us | }
2) 0.813 us | dm_table_put();
2) + 29. 90 us | }
2) + 34.532 us | }
You can add up to 32 functions into this file. Currently we limit it
to 32, but this may change with later improvements.
To add another function, use the append '>>':
# echo sys_read >> /debugfs/tracing/set_graph_function
# cat /debugfs/tracing/set_graph_function
blk_unplug
sys_read
Using the '>' will clear out the function and write anew:
# echo sys_write > /debug/tracing/set_graph_function
# cat /debug/tracing/set_graph_function
sys_write
Note, if you have function graph running while doing this, the small
time between clearing it and updating it will cause the graph to
record all functions. This should not be an issue because after
it sets the filter, only those functions will be recorded from then on.
If you need to only record a particular function then set this
file first before starting the function graph tracer. In the future
this side effect may be corrected.
The set_graph_function file is similar to the set_ftrace_filter but
it does not take wild cards nor does it allow for more than one
function to be set with a single write. There is no technical reason why
this is the case, I just do not have the time yet to implement that.
Note, dynamic ftrace must be enabled for this to appear because it
uses the dynamic ftrace records to match the name to the mcount
call sites.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix time warp bug
Alex Shi, along with Yanmin Zhang have been noticing occasional time
inconsistencies recently. Through their great diagnosis, they found that
the xtime_nsec value used in update_wall_time was occasionally going
negative. After looking through the code for awhile, I realized we have
the possibility for an underflow when three conditions are met in
update_wall_time():
1) We have accumulated a second's worth of nanoseconds, so we
incremented xtime.tv_sec and appropriately decrement xtime_nsec.
(This doesn't cause xtime_nsec to go negative, but it can cause it
to be small).
2) The remaining offset value is large, but just slightly less then
cycle_interval.
3) clocksource_adjust() is speeding up the clock, causing a
corrective amount (compensating for the increase in the multiplier
being multiplied against the unaccumulated offset value) to be
subtracted from xtime_nsec.
This can cause xtime_nsec to underflow.
Unfortunately, since we notify the NTP subsystem via second_overflow()
whenever we accumulate a full second, and this effects the error
accumulation that has already occured, we cannot simply revert the
accumulated second from xtime nor move the second accumulation to after
the clocksource_adjust call without a change in behavior.
This leaves us with (at least) two options:
1) Simply return from clocksource_adjust() without making a change if we
notice the adjustment would cause xtime_nsec to go negative.
This would work, but I'm concerned that if a large adjustment was needed
(due to the error being large), it may be possible to get stuck with an
ever increasing error that becomes too large to correct (since it may
always force xtime_nsec negative). This may just be paranoia on my part.
2) Catch xtime_nsec if it is negative, then add back the amount its
negative to both xtime_nsec and the error.
This second method is consistent with how we've handled earlier rounding
issues, and also has the benefit that the error being added is always in
the oposite direction also always equal or smaller then the correction
being applied. So the risk of a corner case where things get out of
control is lessened.
This patch fixes bug 11970, as tested by Yanmin Zhang
http://bugzilla.kernel.org/show_bug.cgi?id=11970
Reported-by: alex.shi@intel.com
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Acked-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Tested-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Conflicts:
fs/nfsd/nfs4recover.c
Manually fixed above to use new creds API functions, e.g.
nfs4_save_creds().
Signed-off-by: James Morris <jmorris@namei.org>
Impact: graph tracer race/crash fix
There is a nasy race in startup of a new process running the
function graph tracer. In fork.c:
total_forks++;
spin_unlock(¤t->sighand->siglock);
write_unlock_irq(&tasklist_lock);
ftrace_graph_init_task(p);
proc_fork_connector(p);
cgroup_post_fork(p);
return p;
The new task is free to run as soon as the tasklist_lock is released.
This is before the ftrace_graph_init_task. If the task does run
it will be using the same ret_stack and curr_ret_stack as the parent.
This will cause crashes that are difficult to debug.
This patch moves the ftrace_graph_init_task to just after the alloc_pid
code. This fixes the above race.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix to output of stack trace
If a function is not found in the stack of the stack tracer, the
number printed is quite strange. This fixes the algorithm to handle
missing functions better.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
CONFIG_FUNCTION_GRAPH_TRACER depends on FUNCTION_TRACER already,
(turning it non-default) so it so making it default-n is pointless.
So enable it by default - it's a nice extension of the function tracer.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: better trace output of duration for long calls
The old duration output didn't exceeded 9999.999 us to fit the column
and the nanosecs were always 3 numbers. As Ingo suggested, it's better
to have the whole microseconds elapsed time and shift the nanosecs precision
if needed to fit the maximum 7 numbers. And usec need more number, the case
should be rare and important enough to break a bit the column alignment to
show it.
So, depending of the duration value, we now have these patterns:
u.nnn us
uu.nnn us
uuu.nnn us
uuuu.nnn us
uuuuu.nn us
uuuuuu.n us
uuuuuuuu..... us
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend function-graph output: let one know which thread called a function
This patch implements a helper function to print the couple cmdline/pid.
Its output is provided during task switching and on each row if the new
"funcgraph-proc" defualt-off option is set through trace_options file.
The output is center aligned and never exceeds 14 characters. The cmdline
is truncated over 7 chars.
But note that if the pid exceeds 6 characters, the column will overflow (but
the situation is abnormal).
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: feature, let entry function decide to trace or not
This patch lets the graph tracer entry function decide if the tracing
should be done at the end as well. This requires all function graph
entry functions return 1 if it should trace, or 0 if the return should
not be traced.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
Andrew Morton pointed out that the kernel convention of a variable
named page should be of type page struct. The ring buffer uses
a variable named "page" for a pointer to something else.
This patch converts those to be called "bpage" (as in "buffer page").
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new ftrace_graph_stop function
While developing more features of function graph, I hit a bug that
caused the WARN_ON to trigger in the prepare_ftrace_return function.
Well, it was hard for me to find out that was happening because the
bug would not print, it would just cause a hard lockup or reboot.
The reason is that it is not safe to call printk from this function.
Looking further, I also found that it calls unregister_ftrace_graph,
which grabs a mutex and calls kstop machine. This would definitely
lock the box up if it were to trigger.
This patch adds a fast and safe ftrace_graph_stop() which will
stop the function tracer. Then it is safe to call the WARN ON.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new API to ring buffer
This patch adds a new interface into the ring buffer that allows a
page to be read from the ring buffer on a given CPU. For every page
read, one must also be given to allow for a "swap" of the pages.
rpage = ring_buffer_alloc_read_page(buffer);
if (!rpage)
goto err;
ret = ring_buffer_read_page(buffer, &rpage, cpu, full);
if (!ret)
goto empty;
process_page(rpage);
ring_buffer_free_read_page(rpage);
The caller of these functions must handle any waits that are
needed to wait for new data. The ring_buffer_read_page will simply
return 0 if there is no data, or if "full" is set and the writer
is still on the current page.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: get ready for splice changes
This patch moves the commit and timestamp into the beginning of each
data page of the buffer. This change will allow the page to be moved
to another location (disk, network, etc) and still have information
in the page to be able to read it.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix for lockdep and ftrace
The raw_local_irq_save/restore confuses lockdep. This patch
converts them to the local_irq_save/restore variants.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Merge x86/dumpstack into tracing/ftrace because upcoming ftrace changes
depend on cleanups already in x86/dumpstack.
Also merge to latest upstream -rc.
Impact: emit new warning
We periodically waste time tracking down problems from the genirq
framework not respecting IRQF_DISABLED for some shared IRQ cases. Linus
views this as "will not fix", but we're still left with the bugs caused by
this misbehavior.
This patch adds a nag message in request_irq(), so that drivers can fix
their IRQ handlers to avoid this problem.
Note that developers will never see the relevant bugs when they run with
LOCKDEP, so it's no wonder these bugs are hard to find. (That also means
LOCKDEP is overlooking some IRQ-related bugs involving IRQ handlers that
don't set IRQF_DISABLED...)
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix __irq_set_trigger() for IRQ_LEVEL
When recording the irq trigger type, let's also make sure
that IRQ_LEVEL gets set correctly.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend and enable the function graph tracer to 64-bit x86
This patch implements the support for function graph tracer under x86-64.
Both static and dynamic tracing are supported.
This causes some small CPP conditional asm on arch/x86/kernel/ftrace.c I
wanted to use probe_kernel_read/write to make the return address
saving/patching code more generic but it causes tracing recursion.
That would be perhaps useful to implement a notrace version of these
function for other archs ports.
Note that arch/x86/process_64.c is not traced, as in X86-32. I first
thought __switch_to() was responsible of crashes during tracing because I
believed current task were changed inside but that's actually not the
case (actually yes, but not the "current" pointer).
So I will have to investigate to find the functions that harm here, to
enable tracing of the other functions inside (but there is no issue at
this time, while process_64.c stays out of -pg flags).
A little possible race condition is fixed inside this patch too. When the
tracer allocate a return stack dynamically, the current depth is not
initialized before but after. An interrupt could occur at this time and,
after seeing that the return stack is allocated, the tracer could try to
trace it with a random uninitialized depth. It's a prevention, even if I
hadn't problems with it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix "no output from tracer" bug caused by ftrace_update_pid_func()
When disabling single thread function trace using
"echo -1 > set_ftrace_pid", the normal function trace
has to restore to original function, otherwise the normal
function trace will not work well.
Without this commit, something like below:
$ ps |grep 850
850 root 2556 S -/bin/sh
$ echo 850 > /debug/tracing/set_ftrace_pid
$ echo function > /debug/tracing/current_tracer
$ echo 1 > /debug/tracing/tracing_enabled
$ sleep 1
$ echo 0 > /debug/tracing/tracing_enabled
$ cat /debug/tracing/trace_pipe |wc -l
59704
$ echo -1 > /debug/tracing/set_ftrace_pid
$ echo 1 > /debug/tracing/tracing_enabled
$ sleep 1
$ echo 0 > /debug/tracing/tracing_enabled
$ more /debug/tracing/trace_pipe
<====== nothing output now!
it should output trace record.
Signed-off-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The description for 'D' was missing in the comment... (causing me a
minute of WTF followed by looking at more of the code)
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It has been thought that the per-user file descriptors limit would also
limit the resources that a normal user can request via the epoll
interface. Vegard Nossum reported a very simple program (a modified
version attached) that can make a normal user to request a pretty large
amount of kernel memory, well within the its maximum number of fds. To
solve such problem, default limits are now imposed, and /proc based
configuration has been introduced. A new directory has been created,
named /proc/sys/fs/epoll/ and inside there, there are two configuration
points:
max_user_instances = Maximum number of devices - per user
max_user_watches = Maximum number of "watched" fds - per user
The current default for "max_user_watches" limits the memory used by epoll
to store "watches", to 1/32 of the amount of the low RAM. As example, a
256MB 32bit machine, will have "max_user_watches" set to roughly 90000.
That should be enough to not break existing heavy epoll users. The
default value for "max_user_instances" is set to 128, that should be
enough too.
This also changes the userspace, because a new error code can now come out
from EPOLL_CTL_ADD (-ENOSPC). The EMFILE from epoll_create() was already
listed, so that should be ok.
[akpm@linux-foundation.org: use get_current_user()]
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: <stable@kernel.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: Vegard Nossum <vegardno@ifi.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Impact: extend information in /proc/sched_debug
This patch adds uid information in sched_debug for CONFIG_USER_SCHED
Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: prevent divide by zero error in cpu_avg_load_per_task, update
sched, cpusets: fix warning in kernel/cpuset.c
sched: prevent divide by zero error in cpu_avg_load_per_task
* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
irq.h: fix missing/extra kernel-doc
genirq: __irq_set_trigger: change pr_warning to pr_debug
irq: fix typo
x86: apic honour irq affinity which was set in early boot
genirq: fix the affinity setting in setup_irq
genirq: keep affinities set from userspace across free/request_irq()
All architectures now use the generic compat_sys_ptrace, as should every
new architecture that needs 32bit compat (if we'll ever get another).
Remove the now superflous __ARCH_WANT_COMPAT_SYS_PTRACE define, and also
kill a comment about __ARCH_SYS_PTRACE that was added after
__ARCH_SYS_PTRACE was already gone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Regarding the bug addressed in:
4cd4262: sched: prevent divide by zero error in cpu_avg_load_per_task
Linus points out that the fix is not complete:
> There's nothing that keeps gcc from deciding not to reload
> rq->nr_running.
>
> Of course, in _practice_, I don't think gcc ever will (if it decides
> that it will spill, gcc is likely going to decide that it will
> literally spill the local variable to the stack rather than decide to
> reload off the pointer), but it's a valid compiler optimization, and
> it even has a name (rematerialization).
>
> So I suspect that your patch does fix the bug, but it still leaves the
> fairly unlikely _potential_ for it to re-appear at some point.
>
> We have ACCESS_ONCE() as a macro to guarantee that the compiler
> doesn't rematerialize a pointer access. That also would clarify
> the fact that we access something unsafe outside a lock.
So make sure our nr_running value is immutable and cannot change
after we check it for nonzero.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
this warning:
kernel/cpuset.c: In function ‘generate_sched_domains’:
kernel/cpuset.c:588: warning: ‘ndoms’ may be used uninitialized in this function
triggers because GCC does not recognize that ndoms stays uninitialized
only if doms is NULL - but that flow is covered at the end of
generate_sched_domains().
Help out GCC by initializing this variable to 0. (that's prudent anyway)
Also, this function needs a splitup and code flow simplification:
with 160 lines length it's clearly too long.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix build error on branch tracer
This should fix a build error reported on alpha in linux-next:
CC kernel/trace/trace_branch.o
kernel/trace/trace_branch.c: In function 'probe_likely_condition':
kernel/trace/trace_branch.c:44: error: implicit declaration of function 'raw_local_irq_save'
kernel/trace/trace_branch.c:76: error: implicit declaration of function 'raw_local_irq_restore'
Unfortunately, I can't test it since I don't have any Alpha build environment.
Reported-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Move double_lock_balance()/double_unlock_balance() higher to fix the following
with gcc-3.4.6:
CC kernel/sched.o
In file included from kernel/sched.c:1605:
kernel/sched_rt.c: In function `find_lock_lowest_rq':
kernel/sched_rt.c:914: sorry, unimplemented: inlining failed in call to 'double_unlock_balance': function body not available
kernel/sched_rt.c:1077: sorry, unimplemented: called from here
make[2]: *** [kernel/sched.o] Error 1
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, eliminate code
now that warn_on_slowpath() uses warn_slowpath(...,NULL), we can
eliminate warn_on_slowpath() altogether and use warn_slowpath().
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: extend WARN_ON() output with DMI_PRODUCT_NAME
It's very useful for many low level WARN_ON's to find out which
motherboard has the broken BIOS etc... this patch adds a printk
to the WARN_ON code for this.
On architectures without DMI, gcc should optimize the code out.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, code reduction
warn_slowpath is a superset of warn_on_slowpath; just have
warn_on_slowpath call warn_slowpath with a NULL 3rd argument.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: remove unused code
__local_bh_enable has been replaced with _local_bh_enable.
As comments says "it always nests inside local_bh_enable() sections"
has not been valid now. Also there is no reason to use __local_bh_enable
anywhere, so we can remove this useless function.
Signed-off-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: make ftrace position computing more sane
First remove useless ->pos field. Then we needn't check seq_printf
in .show like other place.
Signed-off-by: Liming Wang <liming.wang@windriver.com>
Reviewed-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There are architectures that still have no stacktrace support.
Signed-off-by: Török Edwin <edwintorok@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: increase the visual qualities of the call-graph-tracer output
This patch applies various trace output formatting changes:
- CPU is now a decimal number, followed by a parenthesis.
- Overhead is now on the second column (gives a good visibility)
- Cost is now on the third column, can't exceed 9999.99 us. It is
followed by a virtual line based on a "|" character.
- Functions calls are now the last column on the right. This way, we
haven't dynamic column (which flow is harder to follow) on its right.
- CPU and Overhead have their own option flag. They are default-on but you
can disable them easily:
echo nofuncgraph-cpu > trace_options
echo nofuncgraph-overhead > trace_options
TODO:
_ Refactoring of the thread switch output.
_ Give a default-off option to output the thread and its pid on each row.
_ Provide headers
_ ....
Here is an example of the new trace style:
0) | mutex_unlock() {
0) 0.639 us | __mutex_unlock_slowpath();
0) 1.607 us | }
0) | remove_wait_queue() {
0) 0.616 us | _spin_lock_irqsave();
0) 0.616 us | _spin_unlock_irqrestore();
0) 2.779 us | }
0) 0.495 us | n_tty_set_room();
0) ! 9999.999 us | }
0) | tty_ldisc_deref() {
0) 0.615 us | _spin_lock_irqsave();
0) 0.616 us | _spin_unlock_irqrestore();
0) 2.793 us | }
0) | current_fs_time() {
0) 0.488 us | current_kernel_time();
0) 0.495 us | timespec_trunc();
0) 2.486 us | }
0) ! 9999.999 us | }
0) ! 9999.999 us | }
0) ! 9999.999 us | }
0) | sys_read() {
0) 0.796 us | fget_light();
0) | vfs_read() {
0) | rw_verify_area() {
0) | security_file_permission() {
0) 0.488 us | cap_file_permission();
0) 1.720 us | }
0) 3. 4 us | }
0) | tty_read() {
0) 0.488 us | tty_paranoia_check();
0) | tty_ldisc_ref_wait() {
0) | tty_ldisc_try() {
0) 0.615 us | _spin_lock_irqsave();
0) 0.615 us | _spin_unlock_irqrestore();
0) 5.436 us | }
0) 6.427 us | }
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: enhance the output of the graph-tracer
This patch applies some ideas of Ingo Molnar and Steven Rostedt.
* Output leaf functions in one line with parenthesis, semicolon and duration
output.
* Add a second column (after cpu) for an overhead sign.
if duration > 100 us, "!"
if duration > 10 us, "+"
else " "
* Print output in us with remaining nanosec: u.n
* Print duration on the right end, following the indentation of the functions.
Use also visual clues: "-" on entry call (no duration to output) and "+" on
return (duration output).
The name of the tracer has been fixed as well: function-branch becomes
function_branch.
Here is an example of the new output:
CPU[000] dequeue_entity() { -
CPU[000] update_curr() { -
CPU[000] update_min_vruntime(); + 0.512 us
CPU[000] } + 1.504 us
CPU[000] clear_buddies(); + 0.481 us
CPU[000] update_min_vruntime(); + 0.504 us
CPU[000] } + 4.557 us
CPU[000] hrtick_update() { -
CPU[000] hrtick_start_fair(); + 0.489 us
CPU[000] } + 1.443 us
CPU[000] + } + 14.655 us
CPU[000] + } + 15.678 us
CPU[000] + } + 16.686 us
CPU[000] msecs_to_jiffies(); + 0.481 us
CPU[000] put_prev_task_fair(); + 0.504 us
CPU[000] pick_next_task_fair(); + 0.482 us
CPU[000] pick_next_task_rt(); + 0.504 us
CPU[000] pick_next_task_fair(); + 0.481 us
CPU[000] pick_next_task_idle(); + 0.489 us
CPU[000] _spin_trylock(); + 0.655 us
CPU[000] _spin_unlock(); + 0.609 us
CPU[000] ------------8<---------- thread bash-2794 ------------8<----------
CPU[000] finish_task_switch() { -
CPU[000] _spin_unlock_irq(); + 0.722 us
CPU[000] } + 2.369 us
CPU[000] ! } + 501972.605 us
CPU[000] ! } + 501973.763 us
CPU[000] copy_from_read_buf() { -
CPU[000] _spin_lock_irqsave(); + 0.670 us
CPU[000] _spin_unlock_irqrestore(); + 0.699 us
CPU[000] copy_to_user() { -
CPU[000] might_fault() { -
CPU[000] __might_sleep(); + 0.503 us
CPU[000] } + 1.632 us
CPU[000] __copy_to_user_ll(); + 0.542 us
CPU[000] } + 3.858 us
CPU[000] tty_audit_add_data() { -
CPU[000] _spin_lock_irq(); + 0.609 us
CPU[000] _spin_unlock_irq(); + 0.624 us
CPU[000] } + 3.196 us
CPU[000] _spin_lock_irqsave(); + 0.624 us
CPU[000] _spin_unlock_irqrestore(); + 0.625 us
CPU[000] + } + 13.611 us
CPU[000] copy_from_read_buf() { -
CPU[000] _spin_lock_irqsave(); + 0.624 us
CPU[000] _spin_unlock_irqrestore(); + 0.616 us
CPU[000] } + 2.820 us
CPU[000]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix divide by zero crash in scheduler rebalance irq
While testing the branch profiler, I hit this crash:
divide error: 0000 [#1] PREEMPT SMP
[...]
RIP: 0010:[<ffffffff8024a008>] [<ffffffff8024a008>] cpu_avg_load_per_task+0x50/0x7f
[...]
Call Trace:
<IRQ> <0> [<ffffffff8024fd43>] find_busiest_group+0x3e5/0xcaa
[<ffffffff8025da75>] rebalance_domains+0x2da/0xa21
[<ffffffff80478769>] ? find_next_bit+0x1b2/0x1e6
[<ffffffff8025e2ce>] run_rebalance_domains+0x112/0x19f
[<ffffffff8026d7c2>] __do_softirq+0xa8/0x232
[<ffffffff8020ea7c>] call_softirq+0x1c/0x3e
[<ffffffff8021047a>] do_softirq+0x94/0x1cd
[<ffffffff8026d5eb>] irq_exit+0x6b/0x10e
[<ffffffff8022e6ec>] smp_apic_timer_interrupt+0xd3/0xff
[<ffffffff8020e4b3>] apic_timer_interrupt+0x13/0x20
The code for cpu_avg_load_per_task has:
if (rq->nr_running)
rq->avg_load_per_task = rq->load.weight / rq->nr_running;
The runqueue lock is not held here, and there is nothing that prevents
the rq->nr_running from going to zero after it passes the if condition.
The branch profiler simply made the race window bigger.
This patch saves off the rq->nr_running to a local variable and uses that
for both the condition and the division.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: prevent unnecessary stack recursion
if the resched flag was set before we entered, then don't reschedule.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new "power-tracer" ftrace plugin
This patch adds a C/P-state ftrace plugin that will generate
detailed statistics about the C/P-states that are being used,
so that we can look at detailed decisions that the C/P-state
code is making, rather than the too high level "average"
that we have today.
An example way of using this is:
mount -t debugfs none /sys/kernel/debug
echo cstate > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_enabled
sleep 1
echo 0 > /sys/kernel/debug/tracing/tracing_enabled
cat /sys/kernel/debug/tracing/trace | perl scripts/trace/cstate.pl > out.svg
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: locking fix
We can't call cpuset_cpus_allowed_locked() with the rq lock held.
However, the rq lock merely protects us from (1) cpu_online_mask changing
and (2) someone else changing p->cpus_allowed.
The first can't happen because we're being called from a cpu hotplug
notifier. The second doesn't really matter: we are forcing the task off
a CPU it was affine to, so we're not doing very well anyway.
So we remove the rq lock from this path, and all is good.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
