We have dts property for "ti,sysc-delay-us", and we're using it, but the
wait after OCP softreset only happens if devices are probed in legacy mode.
Let's add a delay after writing the OCP softreset when specified.
Fixes: e0db94fe87 ("bus: ti-sysc: Make OCP reset work for sysstatus and sysconfig reset bits")
Cc: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Early revisions of the AST2600 datasheet are conflicted about the state
of the LPC/eSPI strapping bit (SCU510[6]). Conversations with ASPEED
determined that the reference pinmux configuration tables were in error
and the SCU documentation contained the correct configuration. Update
the driver to reflect the state described in the SCU documentation.
Fixes: 2eda1cdec4 ("pinctrl: aspeed: Add AST2600 pinmux support")
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20191202050110.15340-1-andrew@aj.id.au
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
The IDE driver creates some passthru requests which never get
submitted to the block layer in such a way that blk_account_io_start()
gets called. However, the driver still calls __blk_mq_end_request() in
ide_end_rq() which will call blk_account_io_completion() which tries
to dereferences req->part which is never set. See ide_prep_sense() for
an example of where these requests come from.
To fix this, blk_account_io_completion() and blk_account_io_done()
should do nothing if req->part is not set.
The back trace of this bug is:
BUG: kernel NULL pointer dereference, address: 000002ac
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
*pde = 00000000
Oops: 0002 [#1]
CPU: 0 PID: 237 Comm: kworker/0:1H Not tainted
5.4.0-rc2-00011-g48d9b0d43105e #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1
04/01/2014
Workqueue: kblockd drive_rq_insert_work
EIP: blk_account_io_completion+0x7a/0xf0
Code: 89 54 24 08 31 d2 89 4c 24 04 31 c9 c7 04 24 02 00 00 00 c1 ee
09 e8 f5 21 a6 ff e8 70 5c a7 ff 8b 53 60 8d 04 bd 00 00 00 00 <01> b4
02 ac 02 00 00 8b 9a 88 02 00 00 85 db 74 11 85 d2 74 51 8b
EAX: 00000000 EBX: f5b80000 ECX: 00000000 EDX: 00000000
ESI: 00000000 EDI: 00000000 EBP: f3031e70 ESP: f3031e54
DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010046
CR0: 80050033 CR2: 000002ac CR3: 03c25000 CR4: 000406d0
Call Trace:
<IRQ>
blk_update_request+0x85/0x420
ide_end_rq+0x38/0xa0
ide_complete_rq+0x3d/0x70
cdrom_newpc_intr+0x258/0xba0
ide_intr+0x135/0x250
__handle_irq_event_percpu+0x3e/0x250
handle_irq_event_percpu+0x1f/0x50
handle_irq_event+0x32/0x60
handle_level_irq+0x6c/0x110
handle_irq+0x72/0xa0
</IRQ>
do_IRQ+0x45/0xad
common_interrupt+0x115/0x11c
Fixes: 48d9b0d431 ("block: account statistics for passthrough requests")
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It may cause timeout waiting for sem acquire in VM flush when using
invalidate semaphore for picasso. So it needs to avoid using invalidate
semaphore for piasso.
Signed-off-by: changzhu <Changfeng.Zhu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This reverts commit f2efc6e600.
This was fixed properly for 5.5, but came back via 5.4 merge
into drm-next, so revert it again.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
In prepare_namespace(), do_mount() can be used instead of ksys_mount()
as the first and third argument are const strings in the kernel, the
second and fourth argument are passed through anyway, and the fifth
argument is NULL.
In do_mount_root(), ksys_mount() is called with the first and third
argument being already kernelspace strings, which do not need to be
copied over from userspace to kernelspace (again). The second and
fourth arguments are passed through to do_mount() anyway. The fifth
argument, while already residing in kernelspace, needs to be put into
a page of its own. Then, do_mount() can be used instead of
ksys_mount().
Once this is done, there are no in-kernel users to ksys_mount() left,
which can therefore be removed.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
All three calls to ksys_mount() in initrd-related kernel code can
be switched over to do_mount():
- the first and third arguments are const strings in the kernel,
and do not need to be copied over from userspace;
- the fifth argument is NULL, and therefore no page needs to be,
copied over from userspace;
- the second and fourth argument are passed through anyway.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
In devtmpfs, do_mount() can be called directly instead of complex wrapping
by ksys_mount():
- the first and third arguments are const strings in the kernel,
and do not need to be copied over from userspace;
- the fifth argument is NULL, and therefore no page needs to be
copied over from userspace;
- the second and fourth argument are passed through anyway.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
As the commit 677fe555cb ("serial: imx: Fix recursive locking bug")
has mentioned the uart driver might cause recursive locking between
normal printing and the kernel debugging facilities (e.g. sysrq and
oops). In the commit it gave out suggestion for fixing recursive
locking issue: "The solution is to avoid locking in the sysrq case
and trylock in the oops_in_progress case."
This patch follows the suggestion (also used the exactly same code with
other serial drivers, e.g. amba-pl011.c) to fix the recursive locking
issue, this can avoid stuck caused by deadlock and print out log for
sysrq and oops.
Fixes: 04896a77a9 ("msm_serial: serial driver for MSM7K onboard serial peripheral.")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Link: https://lore.kernel.org/r/20191127141544.4277-2-leo.yan@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 4b927b94d5 ("KVM: arm/arm64: vgic: Introduce find_reg_by_id()")
introduced 'find_reg_by_id()', which looks up a system register only if
the 'id' index parameter identifies a valid system register. As part of
the patch, existing callers of 'find_reg()' were ported over to the new
interface, but this breaks 'index_to_sys_reg_desc()' in the case that the
initial lookup in the vCPU target table fails because we will then call
into 'find_reg()' for the system register table with an uninitialised
'param' as the key to the lookup.
GCC 10 is bright enough to spot this (amongst a tonne of false positives,
but hey!):
| arch/arm64/kvm/sys_regs.c: In function ‘index_to_sys_reg_desc.part.0.isra’:
| arch/arm64/kvm/sys_regs.c:983:33: warning: ‘params.Op2’ may be used uninitialized in this function [-Wmaybe-uninitialized]
| 983 | (u32)(x)->CRn, (u32)(x)->CRm, (u32)(x)->Op2);
| [...]
Revert the hunk of 4b927b94d5 which breaks 'index_to_sys_reg_desc()' so
that the old behaviour of checking the index upfront is restored.
Fixes: 4b927b94d5 ("KVM: arm/arm64: vgic: Introduce find_reg_by_id()")
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191212094049.12437-1-will@kernel.org
Commit 5ace77e0b4 ("nios2: remove __ioremap") removed the following code,
with the argument that cacheflag is always 0 and the expression would
therefore always be false.
if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
IS_MAPPABLE_UNCACHEABLE(last_addr) &&
!(cacheflag & _PAGE_CACHED))
return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
This did not take the "!" in the expression into account. Result is that
nios2 images no longer boot. Restoring the removed code fixes the problem.
Fixes: 5ace77e0b4 ("nios2: remove __ioremap")
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Somehow this was forgotten when Zinc was being split into oddly shaped
pieces, resulting in linker errors. The x86_64 glue has a specific key
generation implementation, but the Arm one does not. However, it can
still receive the NEON speedups by calling the ordinary DH function
using the base point.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Alexei Starovoitov says:
====================
pull-request: bpf 2019-12-11
The following pull-request contains BPF updates for your *net* tree.
We've added 8 non-merge commits during the last 1 day(s) which contain
a total of 10 files changed, 126 insertions(+), 18 deletions(-).
The main changes are:
1) Make BPF trampoline co-exist with ftrace-based tracers, from Alexei.
2) Fix build in minimal configurations, from Arnd.
3) Fix mips, riscv bpf_tail_call limit, from Paul.
4) Fix bpftool segfault, from Toke.
5) Fix samples/bpf, from Daniel.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull MD fixes from Song.
* 'md-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/song/md:
md: make sure desc_nr less than MD_SB_DISKS
md: raid1: check rdev before reference in raid1_sync_request func
raid5: need to set STRIPE_HANDLE for batch head
The imx_soc_device_init functions tries to fetch the ocotp regmap in
order to soc serial number. If regmap fetch fails then a message is
printed but regmap_read is called anyway and the system crashes.
Failing to lookup ocotp regmap shouldn't be a fatal boot error so check
that the pointer is valid.
Only side-effect of ocotp lookup failure now is that serial number will
be reported as all-zeros which is acceptable.
Cc: stable@vger.kernel.org
Fixes: 8267ff89b7 ("ARM: imx: Add serial number support for i.MX6/7 SoCs")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Tested-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Pull AFS fixes from David Howells:
"Fixes for AFS plus one patch to make debugging easier:
- Fix how addresses are matched to server records. This is currently
incorrect which means cache invalidation callbacks from the server
don't necessarily get delivered correctly. This causes stale data
and metadata to be seen under some circumstances.
- Make the dynamic root superblock R/W so that rpm/dnf can reapply
the SELinux label to it when upgrading the Fedora filesystem-afs
package. If the filesystem is R/O, this fails and the upgrade
fails.
It might be better in future to allow setxattr from an LSM to
bypass the R/O protections, if only for pseudo-filesystems.
- Fix the parsing of mountpoint strings. The mountpoint object has to
have a terminal dot, whereas the source/device string passed to
mount should not. This confuses type-forcing suffix detection
leading to the wrong volume variant being mounted.
- Make lookups in the dynamic root superblock for creation events
(such as mkdir) fail with EOPNOTSUPP rather than something like
EEXIST. The dynamic root only allows implicit creation by the
->lookup() method - and only if the target cell exists.
- Fix the looking up of an AFS superblock to include the cell in the
matching key - otherwise all volumes with the same ID number are
treated as the same thing, irrespective of which cell they're in.
- Show the volume name of each volume in the volume records displayed
in /proc/net/afs/<cell>/volumes. This proved useful in debugging as
it provides a way to map the volume IDs to names, where the names
are what appear in /proc/mounts"
* tag 'afs-fixes-20191211' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: Show volume name in /proc/net/afs/<cell>/volumes
afs: Fix missing cell comparison in afs_test_super()
afs: Fix creation calls in the dynamic root to fail with EOPNOTSUPP
afs: Fix mountpoint parsing
afs: Fix SELinux setting security label on /afs
afs: Fix afs_find_server lookups for ipv4 peers
This is currently off and that's not desirable: default imx config is
meant to be generally useful for development and debugging.
Running git bisect between v5.4 and v5.5-rc1 finds this started from
commit 0e4a459f56 ("tracing: Remove unnecessary DEBUG_FS dependency")
Explicit CONFIG_DEBUG_FS=y was earlier removed by
commit c29d541f59 ("ARM: imx_v6_v7_defconfig: Remove unneeded options")
A very similar fix was required before:
commit 7e9eb62688 ("ARM: imx_v6_v7_defconfig: Explicitly restore CONFIG_DEBUG_FS")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Many peripherals are affected by gpio5/2, not just sensors. One of those
is ethernet phy so network boot is current broken.
Fix by renaming reg_sensors and marking it as "always on". Also add a
comment asking for careful testing if this is to be made dynamic in the
future.
The "peri_3v3" naming is similar to imx6sx-sdb and regulator-name is
same string as in schematics (VPERI_3V3).
Fixes: 09e2b10489 ("ARM: dts: imx6ul-14x14-evk: Add sensors' GPIO regulator")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
The reboot register isn't located inside the DCFG controller, but in its
own RST controller. Fix it.
Fixes: 8897f3255c ("arm64: dts: Add support for NXP LS1028A SoC")
Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Currently, open() is called from the user program and it calls the syscall
'sys_openat', not the 'sys_open'. This leads to an error of the program
of user side, due to the fact that the counter maps are zero since no
function such 'sys_open' is called.
This commit adds the kernel bpf program which are attached to the
tracepoint 'sys_enter_openat' and 'sys_enter_openat'.
Fixes: 1da236b6be ("bpf: add a test case for syscalls/sys_{enter|exit}_* tracepoints")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Previously, when this sample is added, commit 1c47910ef8
("samples/bpf: add perf_event+bpf example"), a symbol 'sys_read' and
'sys_write' has been used without no prefixes. But currently there are
no exact symbols with these under kallsyms and this leads to failure.
This commit changes exact compare to substring compare to keep compatible
with exact symbol or prefixed symbol.
Fixes: 1c47910ef8 ("samples/bpf: add perf_event+bpf example")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191205080114.19766-2-danieltimlee@gmail.com
Make BPF trampoline attach its generated assembly code to kernel functions via
register_ftrace_direct() API. It helps ftrace-based tracers co-exist with BPF
trampoline on the same kernel function. It also switches attaching logic from
arch specific text_poke to generic ftrace that is available on many
architectures. text_poke is still necessary for bpf-to-bpf attach and for
bpf_tail_call optimization.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191209000114.1876138-3-ast@kernel.org
If we submit an unknown opcode and have fd == -1, io_op_needs_file()
will return true as we default to needing a file. Then when we go and
assign the file, we find the 'fd' invalid and return -EBADF. We really
should be returning -EINVAL for that case, as we normally do for
unsupported opcodes.
Change io_op_needs_file() to have the following return values:
0 - does not need a file
1 - does need a file
< 0 - error value
and use this to pass back the right value for this invalid case.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
generic/522 (fsx) occasionally fails with a file corruption due to
an insert range operation. The primary characteristic of the
corruption is a misplaced insert range operation that differs from
the requested target offset. The reason for this behavior is a race
between the extent shift sequence of an insert range and a COW
writeback completion that causes a front merge with the first extent
in the shift.
The shift preparation function flushes and unmaps from the target
offset of the operation to the end of the file to ensure no
modifications can be made and page cache is invalidated before file
data is shifted. An insert range operation then splits the extent at
the target offset, if necessary, and begins to shift the start
offset of each extent starting from the end of the file to the start
offset. The shift sequence operates at extent level and so depends
on the preparation sequence to guarantee no changes can be made to
the target range during the shift. If the block immediately prior to
the target offset was dirty and shared, however, it can undergo
writeback and move from the COW fork to the data fork at any point
during the shift. If the block is contiguous with the block at the
start offset of the insert range, it can front merge and alter the
start offset of the extent. Once the shift sequence reaches the
target offset, it shifts based on the latest start offset and
silently changes the target offset of the operation and corrupts the
file.
To address this problem, update the shift preparation code to
stabilize the start boundary along with the full range of the
insert. Also update the existing corruption check to fail if any
extent is shifted with a start offset behind the target offset of
the insert range. This prevents insert from racing with COW
writeback completion and fails loudly in the event of an unexpected
extent shift.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Pull erofs fixes from Gao Xiang:
"Mainly address a regression reported by David recently observed
together with overlayfs due to the improper return value of
listxattr() without xattr. Update outdated expressions in document as
well.
Summary:
- Fix improper return value of listxattr() with no xattr
- Keep up documentation with latest code"
* tag 'erofs-for-5.5-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
erofs: update documentation
erofs: zero out when listxattr is called with no xattr
Pull tracing fixes from Steven Rostedt:
- Remove code I accidentally applied when doing a minor fix up to a
patch, and then using "git commit -a --amend", which pulled in some
other changes I was playing with.
- Remove an used variable in trace_events_inject code
- Fix function graph tracer when it traces a ftrace direct function.
It will now ignore tracing a function that has a ftrace direct
tramploine attached. This is needed for eBPF to use the ftrace direct
code.
* tag 'trace-v5.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Fix function_graph tracer interaction with BPF trampoline
tracing: remove set but not used variable 'buffer'
module: Remove accidental change of module_enable_x()
There's no need to separately check for signals while inside the locked
region, since we're going to do "wait_event_interruptible()" right
afterwards anyway, and the error handling is much simpler there.
The check for whether we had already read anything was also redundant,
since we no longer do the odd merging of reads when there are pending
writers.
But perhaps more importantly, this adds commentary about why we still
need to wake up possible writers even though we didn't read any data,
and why we can skip all the finishing touches now if we get a signal (or
had a signal pending) while waiting for more data.
[ This is a split-out cleanup from my "make pipe IO use exclusive wait
queues" thing, which I can't apply because it triggers a nasty bug in
the GNU make jobserver - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add KASAN_VMALLOC support which now enables vmalloc memory area access
checks as well as enables usage of VMAP_STACK under kasan.
KASAN_VMALLOC changes the way vmalloc and modules areas shadow memory
is handled. With this new approach only top level page tables are
pre-populated and lower levels are filled dynamically upon memory
allocation.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
diag 0x44 is a voluntary undirected yield of a virtual CPU. This has
caused a lot of performance issues in the past.
There is only one caller left, and that one is only executed if diag
0x9c (directed yield) is not present. Given that all hypervisors
implement diag 0x9c anyway, remove the last diag 0x44 to avoid that
more callers will be added.
Worst case that could happen now, if diag 0x9c is not present, is that
a virtual CPU would loop a bit instead of giving its time slice up.
diag 0x44 statistics in debugfs are kept and will always be zero, so
that user space can tell that there are no calls.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
ENOTSUP is just an internal kernel error and should never reach
userspace. The return value of the share function is not exported to
userspace, but to avoid giving bad examples let us use EOPNOTSUPP:
Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
The s390 CPU Measurement sampling facility has an overflow condition
which fires when all entries in a SBD are used.
The measurement alert interrupt is triggered and reads out all samples
in this SDB. It then tests the successor SDB, if this SBD is not full,
the interrupt handler does not read any samples at all from this SDB
The design waits for the hardware to fill this SBD and then trigger
another meassurement alert interrupt.
This scheme works nicely until
an perf_event_overflow() function call discards the sample due to
a too high sampling rate.
The interrupt handler has logic to read out a partially filled SDB
when the perf event overflow condition in linux common code is met.
This causes the CPUM sampling measurement hardware and the PMU
device driver to operate on the same SBD's trailer entry.
This should not happen.
This can be seen here using this trace:
cpumsf_pmu_add: tear:0xb5286000
hw_perf_event_update: sdbt 0xb5286000 full 1 over 0 flush_all:0
hw_perf_event_update: sdbt 0xb5286008 full 0 over 0 flush_all:0
above shows 1. interrupt
hw_perf_event_update: sdbt 0xb5286008 full 1 over 0 flush_all:0
hw_perf_event_update: sdbt 0xb5286008 full 0 over 0 flush_all:0
above shows 2. interrupt
... this goes on fine until...
hw_perf_event_update: sdbt 0xb5286068 full 1 over 0 flush_all:0
perf_push_sample1: overflow
one or more samples read from the IRQ handler are rejected by
perf_event_overflow() and the IRQ handler advances to the next SDB
and modifies the trailer entry of a partially filled SDB.
hw_perf_event_update: sdbt 0xb5286070 full 0 over 0 flush_all:1
timestamp: 14:32:52.519953
Next time the IRQ handler is called for this SDB the trailer entry shows
an overflow count of 19 missed entries.
hw_perf_event_update: sdbt 0xb5286070 full 1 over 19 flush_all:1
timestamp: 14:32:52.970058
Remove access to a follow on SDB when event overflow happened.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Function perf_event_ever_overflow() and perf_event_account_interrupt()
are called every time samples are processed by the interrupt handler.
However function perf_event_account_interrupt() has checks to avoid being
flooded with interrupts (more then 1000 samples are received per
task_tick). Samples are then dropped and a PERF_RECORD_THROTTLED is
added to the perf data. The perf subsystem limit calculation is:
maximum sample frequency := 100000 --> 1 samples per 10 us
task_tick = 10ms = 10000us --> 1000 samples per task_tick
The work flow is
measurement_alert() uses SDBT head and each SBDT points to 511
SDB pages, each with 126 sample entries. After processing 8 SBDs
and for each valid sample calling:
perf_event_overflow()
perf_event_account_interrupts()
there is a considerable amount of samples being dropped, especially when
the sample frequency is very high and near the 100000 limit.
To avoid the high amount of samples being dropped near the end of a
task_tick time frame, increment the sampling interval in case of
dropped events. The CPU Measurement sampling facility on the s390
supports only intervals, specifiing how many CPU cycles have to be
executed before a sample is generated. Increase the interval when the
samples being generated hit the task_tick limit.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
