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3314 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Linus Torvalds
|
56c244382f |
- Make sure the idle timer expires in hardirq context, on PREEMPT_RT
- Make sure the run-queue balance callback is invoked only on the outgoing CPU -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmE9wk4ACgkQEsHwGGHe VUqsGw/+PxWOebjvms0Q0q7JQbp+F/nzAAA/xukjc2IXIsdDwoNYL3HI8gm7B9xz VM5pz97+GOHsT/GramSw1coN9HbkB+k4OiDrwENx4wnxELVWPZpzyhWeMxsb5FDJ laQVbOfsemzRAP/b1LY6Qpo0RRDo9KO0a1jpYPGOPXH+Gagj/iLSnAERFBx/JVrD V1FCz40OHDT7lmCKAS2jb0mHqu8SwDz6nAogUmvQkTI3LlcSxrWW/83Zsx52jsjr PZUaLHKcLRBeEoYs1aV1sPxM0LIrtpUHWDRNhMfLpHYXAMPQz5NV3acb5+nrxs4I 4VfH5oHC/AvWnqPNsD/rHdLrtRuDzxrc0QM7Hptty8q9xaLl4j9MfDieIOmu4lX/ Yg/KR77+141KT7Z2SnKMO4nUiLKsIjkHbAkKizl0xpSorLva3SHKQ+S/F8YWbXTQ I1uYs5wnGt6STVZRc2m9zjK5TesNSnevUNIrCsqteel8msjA63Ya28tqL2TjQmYA U/WMFGStJe3899TAHlkYk+uu0Ywa0UdwYsF7j0dOuJsJoEpu2uRcpuok0CAiY4Jd fa/vLTAtiYhL7CpKwFg7TwApwlvQfnbkE8KDcvDn0jNBxrL7F9v8G8p+gaw3l1zW H9CbEgVLbw/2hEDL/v1YzMkCGDF7Ye83t2buSZU/+XDNT+CpgMM= =ExIs -----END PGP SIGNATURE----- Merge tag 'sched_urgent_for_v5.15_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Borislav Petkov: - Make sure the idle timer expires in hardirq context, on PREEMPT_RT - Make sure the run-queue balance callback is invoked only on the outgoing CPU * tag 'sched_urgent_for_v5.15_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Prevent balance_push() on remote runqueues sched/idle: Make the idle timer expire in hard interrupt context |
||
Thomas Gleixner
|
868ad33bfa |
sched: Prevent balance_push() on remote runqueues
sched_setscheduler() and rt_mutex_setprio() invoke the run-queue balance
callback after changing priorities or the scheduling class of a task. The
run-queue for which the callback is invoked can be local or remote.
That's not a problem for the regular rq::push_work which is serialized with
a busy flag in the run-queue struct, but for the balance_push() work which
is only valid to be invoked on the outgoing CPU that's wrong. It not only
triggers the debug warning, but also leaves the per CPU variable push_work
unprotected, which can result in double enqueues on the stop machine list.
Remove the warning and validate that the function is invoked on the
outgoing CPU.
Fixes:
|
||
Sebastian Andrzej Siewior
|
9848417926 |
sched/idle: Make the idle timer expire in hard interrupt context
The intel powerclamp driver will setup a per-CPU worker with RT priority. The worker will then invoke play_idle() in which it remains in the idle poll loop until it is stopped by the timer it started earlier. That timer needs to expire in hard interrupt context on PREEMPT_RT. Otherwise the timer will expire in ksoftirqd as a SOFT timer but that task won't be scheduled on the CPU because its priority is lower than the priority of the worker which is in the idle loop. Always expire the idle timer in hard interrupt context. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210906113034.jgfxrjdvxnjqgtmc@linutronix.de |
||
|
Linus Torvalds
|
5cbba60596 |
Power management updates for 5.15-rc1
- Address 3 PCI device power management issues (Rafael Wysocki).
- Add Power Limit4 support for Alder Lake to the Intel RAPL power
capping driver (Sumeet Pawnikar).
- Add HWP guaranteed performance change notification support to
the intel_pstate driver (Srinivas Pandruvada).
- Replace deprecated CPU-hotplug functions in code related to power
management (Sebastian Andrzej Siewior).
- Update CPU PM notifiers to use raw spinlocks (Valentin Schneider).
- Add support for 'required-opps' DT property to the generic power
domains (genpd) framework and use this property for I2C on ARM64
sc7180 (Rajendra Nayak).
- Fix Kconfig issue related to genpd (Geert Uytterhoeven).
- Increase energy calculation precision in the Energy Model (Lukasz
Luba).
- Fix kobject deletion in the exit code of the schedutil cpufreq
governor (Kevin Hao).
- Unmark some functions as kernel-doc in the PM core to avoid
false-positive documentation build warnings (Randy Dunlap).
- Check RTC features instead of ops in suspend_test Alexandre
Belloni).
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Merge tag 'pm-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"These address some PCI device power management issues, add new
hardware support to the RAPL power capping driver, add HWP guaranteed
performance change notification support to the intel_pstate driver,
replace deprecated CPU-hotplug functions in a few places, update CPU
PM notifiers to use raw spinlocks, update the PM domains framework
(new DT property support, Kconfig fix), do a couple of cleanups in
code related to system sleep, and improve the energy model and the
schedutil cpufreq governor.
Specifics:
- Address 3 PCI device power management issues (Rafael Wysocki).
- Add Power Limit4 support for Alder Lake to the Intel RAPL power
capping driver (Sumeet Pawnikar).
- Add HWP guaranteed performance change notification support to the
intel_pstate driver (Srinivas Pandruvada).
- Replace deprecated CPU-hotplug functions in code related to power
management (Sebastian Andrzej Siewior).
- Update CPU PM notifiers to use raw spinlocks (Valentin Schneider).
- Add support for 'required-opps' DT property to the generic power
domains (genpd) framework and use this property for I2C on ARM64
sc7180 (Rajendra Nayak).
- Fix Kconfig issue related to genpd (Geert Uytterhoeven).
- Increase energy calculation precision in the Energy Model (Lukasz
Luba).
- Fix kobject deletion in the exit code of the schedutil cpufreq
governor (Kevin Hao).
- Unmark some functions as kernel-doc in the PM core to avoid
false-positive documentation build warnings (Randy Dunlap).
- Check RTC features instead of ops in suspend_test Alexandre
Belloni)"
* tag 'pm-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: domains: Fix domain attach for CONFIG_PM_OPP=n
powercap: Add Power Limit4 support for Alder Lake SoC
cpufreq: intel_pstate: Process HWP Guaranteed change notification
thermal: intel: Allow processing of HWP interrupt
notifier: Remove atomic_notifier_call_chain_robust()
PM: cpu: Make notifier chain use a raw_spinlock_t
PM: sleep: unmark 'state' functions as kernel-doc
arm64: dts: sc7180: Add required-opps for i2c
PM: domains: Add support for 'required-opps' to set default perf state
opp: Don't print an error if required-opps is missing
cpufreq: schedutil: Use kobject release() method to free sugov_tunables
PM: EM: Increase energy calculation precision
PM: sleep: check RTC features instead of ops in suspend_test
PM: sleep: s2idle: Replace deprecated CPU-hotplug functions
cpufreq: Replace deprecated CPU-hotplug functions
powercap: intel_rapl: Replace deprecated CPU-hotplug functions
PCI: PM: Enable PME if it can be signaled from D3cold
PCI: PM: Avoid forcing PCI_D0 for wakeup reasons inconsistently
PCI: Use pci_update_current_state() in pci_enable_device_flags()
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||
|
Linus Torvalds
|
e5e726f7bb |
Updates for locking and atomics:
The regular pile:
- A few improvements to the mutex code
- Documentation updates for atomics to clarify the difference between
cmpxchg() and try_cmpxchg() and to explain the forward progress
expectations.
- Simplification of the atomics fallback generator
- The addition of arch_atomic_long*() variants and generic arch_*()
bitops based on them.
- Add the missing might_sleep() invocations to the down*() operations of
semaphores.
The PREEMPT_RT locking core:
- Scheduler updates to support the state preserving mechanism for
'sleeping' spin- and rwlocks on RT. This mechanism is carefully
preserving the state of the task when blocking on a 'sleeping' spin- or
rwlock and takes regular wake-ups targeted at the same task into
account. The preserved or updated (via a regular wakeup) state is
restored when the lock has been acquired.
- Restructuring of the rtmutex code so it can be utilized and extended
for the RT specific lock variants.
- Restructuring of the ww_mutex code to allow sharing of the ww_mutex
specific functionality for rtmutex based ww_mutexes.
- Header file disentangling to allow substitution of the regular lock
implementations with the PREEMPT_RT variants without creating an
unmaintainable #ifdef mess.
- Shared base code for the PREEMPT_RT specific rw_semaphore and rwlock
implementations. Contrary to the regular rw_semaphores and rwlocks the
PREEMPT_RT implementation is writer unfair because it is infeasible to
do priority inheritance on multiple readers. Experience over the years
has shown that real-time workloads are not the typical workloads which
are sensitive to writer starvation. The alternative solution would be
to allow only a single reader which has been tried and discarded as it
is a major bottleneck especially for mmap_sem. Aside of that many of
the writer starvation critical usage sites have been converted to a
writer side mutex/spinlock and RCU read side protections in the past
decade so that the issue is less prominent than it used to be.
- The actual rtmutex based lock substitutions for PREEMPT_RT enabled
kernels which affect mutex, ww_mutex, rw_semaphore, spinlock_t and
rwlock_t. The spin/rw_lock*() functions disable migration across the
critical section to preserve the existing semantics vs. per CPU
variables.
- Rework of the futex REQUEUE_PI mechanism to handle the case of early
wake-ups which interleave with a re-queue operation to prevent the
situation that a task would be blocked on both the rtmutex associated
to the outer futex and the rtmutex based hash bucket spinlock.
While this situation cannot happen on !RT enabled kernels the changes
make the underlying concurrency problems easier to understand in
general. As a result the difference between !RT and RT kernels is
reduced to the handling of waiting for the critical section. !RT
kernels simply spin-wait as before and RT kernels utilize rcu_wait().
- The substitution of local_lock for PREEMPT_RT with a spinlock which
protects the critical section while staying preemptible. The CPU
locality is established by disabling migration.
The underlying concepts of this code have been in use in PREEMPT_RT for
way more than a decade. The code has been refactored several times over
the years and this final incarnation has been optimized once again to be
as non-intrusive as possible, i.e. the RT specific parts are mostly
isolated.
It has been extensively tested in the 5.14-rt patch series and it has
been verified that !RT kernels are not affected by these changes.
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Merge tag 'locking-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking and atomics updates from Thomas Gleixner:
"The regular pile:
- A few improvements to the mutex code
- Documentation updates for atomics to clarify the difference between
cmpxchg() and try_cmpxchg() and to explain the forward progress
expectations.
- Simplification of the atomics fallback generator
- The addition of arch_atomic_long*() variants and generic arch_*()
bitops based on them.
- Add the missing might_sleep() invocations to the down*() operations
of semaphores.
The PREEMPT_RT locking core:
- Scheduler updates to support the state preserving mechanism for
'sleeping' spin- and rwlocks on RT.
This mechanism is carefully preserving the state of the task when
blocking on a 'sleeping' spin- or rwlock and takes regular wake-ups
targeted at the same task into account. The preserved or updated
(via a regular wakeup) state is restored when the lock has been
acquired.
- Restructuring of the rtmutex code so it can be utilized and
extended for the RT specific lock variants.
- Restructuring of the ww_mutex code to allow sharing of the ww_mutex
specific functionality for rtmutex based ww_mutexes.
- Header file disentangling to allow substitution of the regular lock
implementations with the PREEMPT_RT variants without creating an
unmaintainable #ifdef mess.
- Shared base code for the PREEMPT_RT specific rw_semaphore and
rwlock implementations.
Contrary to the regular rw_semaphores and rwlocks the PREEMPT_RT
implementation is writer unfair because it is infeasible to do
priority inheritance on multiple readers. Experience over the years
has shown that real-time workloads are not the typical workloads
which are sensitive to writer starvation.
The alternative solution would be to allow only a single reader
which has been tried and discarded as it is a major bottleneck
especially for mmap_sem. Aside of that many of the writer
starvation critical usage sites have been converted to a writer
side mutex/spinlock and RCU read side protections in the past
decade so that the issue is less prominent than it used to be.
- The actual rtmutex based lock substitutions for PREEMPT_RT enabled
kernels which affect mutex, ww_mutex, rw_semaphore, spinlock_t and
rwlock_t. The spin/rw_lock*() functions disable migration across
the critical section to preserve the existing semantics vs per-CPU
variables.
- Rework of the futex REQUEUE_PI mechanism to handle the case of
early wake-ups which interleave with a re-queue operation to
prevent the situation that a task would be blocked on both the
rtmutex associated to the outer futex and the rtmutex based hash
bucket spinlock.
While this situation cannot happen on !RT enabled kernels the
changes make the underlying concurrency problems easier to
understand in general. As a result the difference between !RT and
RT kernels is reduced to the handling of waiting for the critical
section. !RT kernels simply spin-wait as before and RT kernels
utilize rcu_wait().
- The substitution of local_lock for PREEMPT_RT with a spinlock which
protects the critical section while staying preemptible. The CPU
locality is established by disabling migration.
The underlying concepts of this code have been in use in PREEMPT_RT for
way more than a decade. The code has been refactored several times over
the years and this final incarnation has been optimized once again to be
as non-intrusive as possible, i.e. the RT specific parts are mostly
isolated.
It has been extensively tested in the 5.14-rt patch series and it has
been verified that !RT kernels are not affected by these changes"
* tag 'locking-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (92 commits)
locking/rtmutex: Return success on deadlock for ww_mutex waiters
locking/rtmutex: Prevent spurious EDEADLK return caused by ww_mutexes
locking/rtmutex: Dequeue waiter on ww_mutex deadlock
locking/rtmutex: Dont dereference waiter lockless
locking/semaphore: Add might_sleep() to down_*() family
locking/ww_mutex: Initialize waiter.ww_ctx properly
static_call: Update API documentation
locking/local_lock: Add PREEMPT_RT support
locking/spinlock/rt: Prepare for RT local_lock
locking/rtmutex: Add adaptive spinwait mechanism
locking/rtmutex: Implement equal priority lock stealing
preempt: Adjust PREEMPT_LOCK_OFFSET for RT
locking/rtmutex: Prevent lockdep false positive with PI futexes
futex: Prevent requeue_pi() lock nesting issue on RT
futex: Simplify handle_early_requeue_pi_wakeup()
futex: Reorder sanity checks in futex_requeue()
futex: Clarify comment in futex_requeue()
futex: Restructure futex_requeue()
futex: Correct the number of requeued waiters for PI
futex: Remove bogus condition for requeue PI
...
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||
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Linus Torvalds
|
5d3c0db459 |
Scheduler changes for v5.15 are:
- The biggest change in this cycle is scheduler support for asymmetric scheduling affinity, to support the execution of legacy 32-bit tasks on AArch32 systems that also have 64-bit-only CPUs. Architectures can fill in this functionality by defining their own task_cpu_possible_mask(p). When this is done, the scheduler will make sure the task will only be scheduled on CPUs that support it. (The actual arm64 specific changes are not part of this tree.) For other architectures there will be no change in functionality. - Add cgroup SCHED_IDLE support - Increase node-distance flexibility & delay determining it until a CPU is brought online. (This enables platforms where node distance isn't final until the CPU is only.) - Deadline scheduler enhancements & fixes - Misc fixes & cleanups. Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmEsrDgRHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1gMxBAAmzXPnDm1pDBBUaEwc+DynNGHNxZcBO5E CaNyfywp4GMA+OC3JzUgDg1B9uvKQRdBGtv6SZ8OcyhJMfmkEvjt5/wYUrcdtQVP TA2lt80/Is8LQMnvcz7X0gmsLt+fXWQTF8ik1KT4wsi/k03Xw8BH11zHct6sV2QN NNQ+7BEjqU1HA1UXJFiaoGtWF0gdh29VyE5dSzfAis79L0XUQadS512LJKin/AK0 wYz8E+L7QIrjhfX9FQdOrR6da4TK6jAXyEY6a9dpaMHnFdtxuwhT4/BPtovNTeeY yxEZm3qSZbpghWHsMEa6Z4GIeLE6aNi3wcHt10fgdZDdotSRsNZuF6gi4A8nhRC+ 6wm+fCcFGEIBCL6eE/16Wms6YMdFfuiEAgtJGNy7GGyfH3/mS6u8eylXbLZncYXn DFHY+xUvmVZSzoPzcnYXEy4FB3kywNL7WBFxyhdXf5/EvWmmtHi4K3jVQ8jaqvhL MDk3NX9Hd0ariff3zUltWhMY5ouj6bIbBZmWWnD3s1xQT68VvE563cq0qH15dlnr j5M71eNRWvoOdZKzflgjRZzmdQtsZQ51tiMA6W6ZRfwYkHjb70qiia0r5GFf41X1 MYelmcaA8+RjKrQ5etxzzDjoXl0xDXiZric6gRQHjG1Y1Zm2rVaoD+vkJGD5TQJ0 2XTOGQgAxh4= =VdGE -----END PGP SIGNATURE----- Merge tag 'sched-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - The biggest change in this cycle is scheduler support for asymmetric scheduling affinity, to support the execution of legacy 32-bit tasks on AArch32 systems that also have 64-bit-only CPUs. Architectures can fill in this functionality by defining their own task_cpu_possible_mask(p). When this is done, the scheduler will make sure the task will only be scheduled on CPUs that support it. (The actual arm64 specific changes are not part of this tree.) For other architectures there will be no change in functionality. - Add cgroup SCHED_IDLE support - Increase node-distance flexibility & delay determining it until a CPU is brought online. (This enables platforms where node distance isn't final until the CPU is only.) - Deadline scheduler enhancements & fixes - Misc fixes & cleanups. * tag 'sched-core-2021-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) eventfd: Make signal recursion protection a task bit sched/fair: Mark tg_is_idle() an inline in the !CONFIG_FAIR_GROUP_SCHED case sched: Introduce dl_task_check_affinity() to check proposed affinity sched: Allow task CPU affinity to be restricted on asymmetric systems sched: Split the guts of sched_setaffinity() into a helper function sched: Introduce task_struct::user_cpus_ptr to track requested affinity sched: Reject CPU affinity changes based on task_cpu_possible_mask() cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq() cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 sched: Introduce task_cpu_possible_mask() to limit fallback rq selection sched: Cgroup SCHED_IDLE support sched/topology: Skip updating masks for non-online nodes sched: Replace deprecated CPU-hotplug functions. sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS sched: Fix UCLAMP_FLAG_IDLE setting sched/deadline: Fix missing clock update in migrate_task_rq_dl() sched/fair: Avoid a second scan of target in select_idle_cpu sched/fair: Use prev instead of new target as recent_used_cpu sched: Don't report SCHED_FLAG_SUGOV in sched_getattr() ... |
||
|
Linus Torvalds
|
4ca4256453 |
Merge branch 'core-rcu.2021.08.28a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU updates from Paul McKenney:
"RCU changes for this cycle were:
- Documentation updates
- Miscellaneous fixes
- Offloaded-callbacks updates
- Updates to the nolibc library
- Tasks-RCU updates
- In-kernel torture-test updates
- Torture-test scripting, perhaps most notably the pinning of
torture-test guest OSes so as to force differences in memory
latency. For example, in a two-socket system, a four-CPU guest OS
will have one pair of its CPUs pinned to threads in a single core
on one socket and the other pair pinned to threads in a single core
on the other socket. This approach proved able to force race
conditions that earlier testing missed. Some of these race
conditions are still being tracked down"
* 'core-rcu.2021.08.28a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (61 commits)
torture: Replace deprecated CPU-hotplug functions.
rcu: Replace deprecated CPU-hotplug functions
rcu: Print human-readable message for schedule() in RCU reader
rcu: Explain why rcu_all_qs() is a stub in preemptible TREE RCU
rcu: Use per_cpu_ptr to get the pointer of per_cpu variable
rcu: Remove useless "ret" update in rcu_gp_fqs_loop()
rcu: Mark accesses in tree_stall.h
rcu: Make rcu_gp_init() and rcu_gp_fqs_loop noinline to conserve stack
rcu: Mark lockless ->qsmask read in rcu_check_boost_fail()
srcutiny: Mark read-side data races
rcu: Start timing stall repetitions after warning complete
rcu: Do not disable GP stall detection in rcu_cpu_stall_reset()
rcu/tree: Handle VM stoppage in stall detection
rculist: Unify documentation about missing list_empty_rcu()
rcu: Mark accesses to ->rcu_read_lock_nesting
rcu: Weaken ->dynticks accesses and updates
rcu: Remove special bit at the bottom of the ->dynticks counter
rcu: Fix stall-warning deadlock due to non-release of rcu_node ->lock
rcu: Fix to include first blocked task in stall warning
torture: Make kvm-test-1-run-qemu.sh check for reboot loops
...
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||
|
Sebastian Andrzej Siewior
|
e681dcbaa4 |
sched: Fix get_push_task() vs migrate_disable()
push_rt_task() attempts to move the currently running task away if the
next runnable task has migration disabled and therefore is pinned on the
current CPU.
The current task is retrieved via get_push_task() which only checks for
nr_cpus_allowed == 1, but does not check whether the task has migration
disabled and therefore cannot be moved either. The consequence is a
pointless invocation of the migration thread which correctly observes
that the task cannot be moved.
Return NULL if the task has migration disabled and cannot be moved to
another CPU.
Fixes:
|
||
Ingo Molnar
|
366e7ad6ba |
sched/fair: Mark tg_is_idle() an inline in the !CONFIG_FAIR_GROUP_SCHED case
It's not actually used in the !CONFIG_FAIR_GROUP_SCHED case:
kernel/sched/fair.c:488:12: warning: ‘tg_is_idle’ defined but not used [-Wunused-function]
Keep around a placeholder nevertheless, for API completeness. Mark it inline,
so the compiler doesn't think it must be used.
Fixes:
|
||
Rafael J. Wysocki
|
43dde64bb1 | Merge back cpufreq changes for v5.15. | ||
Will Deacon
|
234b8ab647 |
sched: Introduce dl_task_check_affinity() to check proposed affinity
In preparation for restricting the affinity of a task during execve() on arm64, introduce a new dl_task_check_affinity() helper function to give an indication as to whether the restricted mask is admissible for a deadline task. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Link: https://lore.kernel.org/r/20210730112443.23245-10-will@kernel.org |
||
|
Will Deacon
|
07ec77a1d4 |
sched: Allow task CPU affinity to be restricted on asymmetric systems
Asymmetric systems may not offer the same level of userspace ISA support
across all CPUs, meaning that some applications cannot be executed by
some CPUs. As a concrete example, upcoming arm64 big.LITTLE designs do
not feature support for 32-bit applications on both clusters.
Although userspace can carefully manage the affinity masks for such
tasks, one place where it is particularly problematic is execve()
because the CPU on which the execve() is occurring may be incompatible
with the new application image. In such a situation, it is desirable to
restrict the affinity mask of the task and ensure that the new image is
entered on a compatible CPU. From userspace's point of view, this looks
the same as if the incompatible CPUs have been hotplugged off in the
task's affinity mask. Similarly, if a subsequent execve() reverts to
a compatible image, then the old affinity is restored if it is still
valid.
In preparation for restricting the affinity mask for compat tasks on
arm64 systems without uniform support for 32-bit applications, introduce
{force,relax}_compatible_cpus_allowed_ptr(), which respectively restrict
and restore the affinity mask for a task based on the compatible CPUs.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20210730112443.23245-9-will@kernel.org
|
||
|
Will Deacon
|
db3b02ae89 |
sched: Split the guts of sched_setaffinity() into a helper function
In preparation for replaying user affinity requests using a saved mask, split sched_setaffinity() up so that the initial task lookup and security checks are only performed when the request is coming directly from userspace. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com> Link: https://lore.kernel.org/r/20210730112443.23245-8-will@kernel.org |
||
|
Will Deacon
|
b90ca8badb |
sched: Introduce task_struct::user_cpus_ptr to track requested affinity
In preparation for saving and restoring the user-requested CPU affinity mask of a task, add a new cpumask_t pointer to 'struct task_struct'. If the pointer is non-NULL, then the mask is copied across fork() and freed on task exit. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com> Link: https://lore.kernel.org/r/20210730112443.23245-7-will@kernel.org |
||
|
Will Deacon
|
234a503e67 |
sched: Reject CPU affinity changes based on task_cpu_possible_mask()
Reject explicit requests to change the affinity mask of a task via set_cpus_allowed_ptr() if the requested mask is not a subset of the mask returned by task_cpu_possible_mask(). This ensures that the 'cpus_mask' for a given task cannot contain CPUs which are incapable of executing it, except in cases where the affinity is forced. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com> Reviewed-by: Quentin Perret <qperret@google.com> Link: https://lore.kernel.org/r/20210730112443.23245-6-will@kernel.org |
||
|
Will Deacon
|
97c0054dbe |
cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
select_fallback_rq() only needs to recheck for an allowed CPU if the affinity mask of the task has changed since the last check. Return a 'bool' from cpuset_cpus_allowed_fallback() to indicate whether the affinity mask was updated, and use this to elide the allowed check when the mask has been left alone. No functional change. Suggested-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Link: https://lore.kernel.org/r/20210730112443.23245-5-will@kernel.org |
||
|
Will Deacon
|
9ae606bc74 |
sched: Introduce task_cpu_possible_mask() to limit fallback rq selection
Asymmetric systems may not offer the same level of userspace ISA support across all CPUs, meaning that some applications cannot be executed by some CPUs. As a concrete example, upcoming arm64 big.LITTLE designs do not feature support for 32-bit applications on both clusters. On such a system, we must take care not to migrate a task to an unsupported CPU when forcefully moving tasks in select_fallback_rq() in response to a CPU hot-unplug operation. Introduce a task_cpu_possible_mask() hook which, given a task argument, allows an architecture to return a cpumask of CPUs that are capable of executing that task. The default implementation returns the cpu_possible_mask, since sane machines do not suffer from per-cpu ISA limitations that affect scheduling. The new mask is used when selecting the fallback runqueue as a last resort before forcing a migration to the first active CPU. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com> Reviewed-by: Quentin Perret <qperret@google.com> Link: https://lore.kernel.org/r/20210730112443.23245-2-will@kernel.org |
||
Josh Don
|
304000390f |
sched: Cgroup SCHED_IDLE support
This extends SCHED_IDLE to cgroups.
Interface: cgroup/cpu.idle.
0: default behavior
1: SCHED_IDLE
Extending SCHED_IDLE to cgroups means that we incorporate the existing
aspects of SCHED_IDLE; a SCHED_IDLE cgroup will count all of its
descendant threads towards the idle_h_nr_running count of all of its
ancestor cgroups. Thus, sched_idle_rq() will work properly.
Additionally, SCHED_IDLE cgroups are configured with minimum weight.
There are two key differences between the per-task and per-cgroup
SCHED_IDLE interface:
- The cgroup interface allows tasks within a SCHED_IDLE hierarchy to
maintain their relative weights. The entity that is "idle" is the
cgroup, not the tasks themselves.
- Since the idle entity is the cgroup, our SCHED_IDLE wakeup preemption
decision is not made by comparing the current task with the woken
task, but rather by comparing their matching sched_entity.
A typical use-case for this is a user that creates an idle and a
non-idle subtree. The non-idle subtree will dominate competition vs
the idle subtree, but the idle subtree will still be high priority vs
other users on the system. The latter is accomplished via comparing
matching sched_entity in the waken preemption path (this could also be
improved by making the sched_idle_rq() decision dependent on the
perspective of a specific task).
For now, we maintain the existing SCHED_IDLE semantics. Future patches
may make improvements that extend how we treat SCHED_IDLE entities.
The per-task_group idle field is an integer that currently only holds
either a 0 or a 1. This is explicitly typed as an integer to allow for
further extensions to this API. For example, a negative value may
indicate a highly latency-sensitive cgroup that should be preferred
for preemption/placement/etc.
Signed-off-by: Josh Don <joshdon@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20210730020019.1487127-2-joshdon@google.com
|
||
Valentin Schneider
|
0083242c93 |
sched/topology: Skip updating masks for non-online nodes
The scheduler currently expects NUMA node distances to be stable from init onwards, and as a consequence builds the related data structures once-and-for-all at init (see sched_init_numa()). Unfortunately, on some architectures node distance is unreliable for offline nodes and may very well change upon onlining. Skip over offline nodes during sched_init_numa(). Track nodes that have been onlined at least once, and trigger a build of a node's NUMA masks when it is first onlined post-init. Reported-by: Geetika Moolchandani <Geetika.Moolchandani1@ibm.com> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210818074333.48645-1-srikar@linux.vnet.ibm.com |
||
Peter Zijlstra
|
3c474b3239 |
sched: Fix Core-wide rq->lock for uninitialized CPUs
Eugene tripped over the case where rq_lock(), as called in a
for_each_possible_cpu() loop came apart because rq->core hadn't been
setup yet.
This is a somewhat unusual, but valid case.
Rework things such that rq->core is initialized to point at itself. IOW
initialize each CPU as a single threaded Core. CPU online will then join
the new CPU (thread) to an existing Core where needed.
For completeness sake, have CPU offline fully undo the state so as to
not presume the topology will match the next time it comes online.
Fixes:
|
||
|
Thomas Gleixner
|
6991436c2b |
sched/core: Provide a scheduling point for RT locks
RT enabled kernels substitute spin/rwlocks with 'sleeping' variants based on rtmutexes. Blocking on such a lock is similar to preemption versus: - I/O scheduling and worker handling, because these functions might block on another substituted lock, or come from a lock contention within these functions. - RCU considers this like a preemption, because the task might be in a read side critical section. Add a separate scheduling point for this, and hand a new scheduling mode argument to __schedule() which allows, along with separate mode masks, to handle this gracefully from within the scheduler, without proliferating that to other subsystems like RCU. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211302.372319055@linutronix.de |
||
|
Thomas Gleixner
|
b4bfa3fcfe |
sched/core: Rework the __schedule() preempt argument
PREEMPT_RT needs to hand a special state into __schedule() when a task blocks on a 'sleeping' spin/rwlock. This is required to handle rcu_note_context_switch() correctly without having special casing in the RCU code. From an RCU point of view the blocking on the sleeping spinlock is equivalent to preemption, because the task might be in a read side critical section. schedule_debug() also has a check which would trigger with the !preempt case, but that could be handled differently. To avoid adding another argument and extra checks which cannot be optimized out by the compiler, the following solution has been chosen: - Replace the boolean 'preempt' argument with an unsigned integer 'sched_mode' argument and define constants to hand in: (0 == no preemption, 1 = preemption). - Add two masks to apply on that mode: one for the debug/rcu invocations, and one for the actual scheduling decision. For a non RT kernel these masks are UINT_MAX, i.e. all bits are set, which allows the compiler to optimize the AND operation out, because it is not masking out anything. IOW, it's not different from the boolean. RT enabled kernels will define these masks separately. No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211302.315473019@linutronix.de |
||
|
Thomas Gleixner
|
5f220be214 |
sched/wakeup: Prepare for RT sleeping spin/rwlocks
Waiting for spinlocks and rwlocks on non RT enabled kernels is task::state
preserving. Any wakeup which matches the state is valid.
RT enabled kernels substitutes them with 'sleeping' spinlocks. This creates
an issue vs. task::__state.
In order to block on the lock, the task has to overwrite task::__state and a
consecutive wakeup issued by the unlocker sets the state back to
TASK_RUNNING. As a consequence the task loses the state which was set
before the lock acquire and also any regular wakeup targeted at the task
while it is blocked on the lock.
To handle this gracefully, add a 'saved_state' member to task_struct which
is used in the following way:
1) When a task blocks on a 'sleeping' spinlock, the current state is saved
in task::saved_state before it is set to TASK_RTLOCK_WAIT.
2) When the task unblocks and after acquiring the lock, it restores the saved
state.
3) When a regular wakeup happens for a task while it is blocked then the
state change of that wakeup is redirected to operate on task::saved_state.
This is also required when the task state is running because the task
might have been woken up from the lock wait and has not yet restored
the saved state.
To make it complete, provide the necessary helpers to save and restore the
saved state along with the necessary documentation how the RT lock blocking
is supposed to work.
For non-RT kernels there is no functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211302.258751046@linutronix.de
|
||
|
Thomas Gleixner
|
43295d73ad |
sched/wakeup: Split out the wakeup ->__state check
RT kernels have a slightly more complicated handling of wakeups due to 'sleeping' spin/rwlocks. If a task is blocked on such a lock then the original state of the task is preserved over the blocking period, and any regular (non lock related) wakeup has to be targeted at the saved state to ensure that these wakeups are not lost. Once the task acquires the lock it restores the task state from the saved state. To avoid cluttering try_to_wake_up() with that logic, split the wakeup state check out into an inline helper and use it at both places where task::__state is checked against the state argument of try_to_wake_up(). No functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211302.088945085@linutronix.de |
||
|
Sebastian Andrzej Siewior
|
746f5ea9c4 |
sched: Replace deprecated CPU-hotplug functions.
The functions get_online_cpus() and put_online_cpus() have been deprecated during the CPU hotplug rework. They map directly to cpus_read_lock() and cpus_read_unlock(). Replace deprecated CPU-hotplug functions with the official version. The behavior remains unchanged. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210803141621.780504-33-bigeasy@linutronix.de |
||
Frederic Weisbecker
|
508958259b |
rcu: Explain why rcu_all_qs() is a stub in preemptible TREE RCU
The cond_resched() function reports an RCU quiescent state only in non-preemptible TREE RCU implementation. This commit therefore adds a comment explaining why cond_resched() does nothing in preemptible kernels. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Uladzislau Rezki <urezki@gmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
||
Kevin Hao
|
e5c6b312ce |
cpufreq: schedutil: Use kobject release() method to free sugov_tunables
The struct sugov_tunables is protected by the kobject, so we can't free
it directly. Otherwise we would get a call trace like this:
ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x30
WARNING: CPU: 3 PID: 720 at lib/debugobjects.c:505 debug_print_object+0xb8/0x100
Modules linked in:
CPU: 3 PID: 720 Comm: a.sh Tainted: G W 5.14.0-rc1-next-20210715-yocto-standard+ #507
Hardware name: Marvell OcteonTX CN96XX board (DT)
pstate: 40400009 (nZcv daif +PAN -UAO -TCO BTYPE=--)
pc : debug_print_object+0xb8/0x100
lr : debug_print_object+0xb8/0x100
sp : ffff80001ecaf910
x29: ffff80001ecaf910 x28: ffff00011b10b8d0 x27: ffff800011043d80
x26: ffff00011a8f0000 x25: ffff800013cb3ff0 x24: 0000000000000000
x23: ffff80001142aa68 x22: ffff800011043d80 x21: ffff00010de46f20
x20: ffff800013c0c520 x19: ffff800011d8f5b0 x18: 0000000000000010
x17: 6e6968207473696c x16: 5f72656d6974203a x15: 6570797420746365
x14: 6a626f2029302065 x13: 303378302f307830 x12: 2b6e665f72656d69
x11: ffff8000124b1560 x10: ffff800012331520 x9 : ffff8000100ca6b0
x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 0000000000000001
x5 : ffff800011d8c000 x4 : ffff800011d8c740 x3 : 0000000000000000
x2 : ffff0001108301c0 x1 : ab3c90eedf9c0f00 x0 : 0000000000000000
Call trace:
debug_print_object+0xb8/0x100
__debug_check_no_obj_freed+0x1c0/0x230
debug_check_no_obj_freed+0x20/0x88
slab_free_freelist_hook+0x154/0x1c8
kfree+0x114/0x5d0
sugov_exit+0xbc/0xc0
cpufreq_exit_governor+0x44/0x90
cpufreq_set_policy+0x268/0x4a8
store_scaling_governor+0xe0/0x128
store+0xc0/0xf0
sysfs_kf_write+0x54/0x80
kernfs_fop_write_iter+0x128/0x1c0
new_sync_write+0xf0/0x190
vfs_write+0x2d4/0x478
ksys_write+0x74/0x100
__arm64_sys_write+0x24/0x30
invoke_syscall.constprop.0+0x54/0xe0
do_el0_svc+0x64/0x158
el0_svc+0x2c/0xb0
el0t_64_sync_handler+0xb0/0xb8
el0t_64_sync+0x198/0x19c
irq event stamp: 5518
hardirqs last enabled at (5517): [<ffff8000100cbd7c>] console_unlock+0x554/0x6c8
hardirqs last disabled at (5518): [<ffff800010fc0638>] el1_dbg+0x28/0xa0
softirqs last enabled at (5504): [<ffff8000100106e0>] __do_softirq+0x4d0/0x6c0
softirqs last disabled at (5483): [<ffff800010049548>] irq_exit+0x1b0/0x1b8
So split the original sugov_tunables_free() into two functions,
sugov_clear_global_tunables() is just used to clear the global_tunables
and the new sugov_tunables_free() is used as kobj_type::release to
release the sugov_tunables safely.
Fixes:
|
||
Quentin Perret
|
f4dddf90d5 |
sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS
SCHED_FLAG_KEEP_PARAMS can be passed to sched_setattr to specify that the call must not touch scheduling parameters (nice or priority). This is particularly handy for uclamp when used in conjunction with SCHED_FLAG_KEEP_POLICY as that allows to issue a syscall that only impacts uclamp values. However, sched_setattr always checks whether the priorities and nice values passed in sched_attr are valid first, even if those never get used down the line. This is useless at best since userspace can trivially bypass this check to set the uclamp values by specifying low priorities. However, it is cumbersome to do so as there is no single expression of this that skips both RT and CFS checks at once. As such, userspace needs to query the task policy first with e.g. sched_getattr and then set sched_attr.sched_priority accordingly. This is racy and slower than a single call. As the priority and nice checks are useless when SCHED_FLAG_KEEP_PARAMS is specified, simply inherit them in this case to match the policy inheritance of SCHED_FLAG_KEEP_POLICY. Reported-by: Wei Wang <wvw@google.com> Signed-off-by: Quentin Perret <qperret@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Reviewed-by: Qais Yousef <qais.yousef@arm.com> Link: https://lore.kernel.org/r/20210805102154.590709-3-qperret@google.com |
||
|
Quentin Perret
|
ca4984a7dd |
sched: Fix UCLAMP_FLAG_IDLE setting
The UCLAMP_FLAG_IDLE flag is set on a runqueue when dequeueing the last
uclamp active task (that is, when buckets.tasks reaches 0 for all
buckets) to maintain the last uclamp.max and prevent blocked util from
suddenly becoming visible.
However, there is an asymmetry in how the flag is set and cleared which
can lead to having the flag set whilst there are active tasks on the rq.
Specifically, the flag is cleared in the uclamp_rq_inc() path, which is
called at enqueue time, but set in uclamp_rq_dec_id() which is called
both when dequeueing a task _and_ in the update_uclamp_active() path. As
a result, when both uclamp_rq_{dec,ind}_id() are called from
update_uclamp_active(), the flag ends up being set but not cleared,
hence leaving the runqueue in a broken state.
Fix this by clearing the flag in update_uclamp_active() as well.
Fixes:
|
||
Dietmar Eggemann
|
b4da13aa28 |
sched/deadline: Fix missing clock update in migrate_task_rq_dl()
A missing clock update is causing the following warning:
rq->clock_update_flags < RQCF_ACT_SKIP
WARNING: CPU: 112 PID: 2041 at kernel/sched/sched.h:1453
sub_running_bw.isra.0+0x190/0x1a0
...
CPU: 112 PID: 2041 Comm: sugov:112 Tainted: G W 5.14.0-rc1 #1
Hardware name: WIWYNN Mt.Jade Server System
B81.030Z1.0007/Mt.Jade Motherboard, BIOS 1.6.20210526 (SCP:
1.06.20210526) 2021/05/26
...
Call trace:
sub_running_bw.isra.0+0x190/0x1a0
migrate_task_rq_dl+0xf8/0x1e0
set_task_cpu+0xa8/0x1f0
try_to_wake_up+0x150/0x3d4
wake_up_q+0x64/0xc0
__up_write+0xd0/0x1c0
up_write+0x4c/0x2b0
cppc_set_perf+0x120/0x2d0
cppc_cpufreq_set_target+0xe0/0x1a4 [cppc_cpufreq]
__cpufreq_driver_target+0x74/0x140
sugov_work+0x64/0x80
kthread_worker_fn+0xe0/0x230
kthread+0x138/0x140
ret_from_fork+0x10/0x18
The task causing this is the `cppc_fie` DL task introduced by
commit
|
||
Mel Gorman
|
56498cfb04 |
sched/fair: Avoid a second scan of target in select_idle_cpu
When select_idle_cpu starts scanning for an idle CPU, it starts with a target CPU that has already been checked by select_idle_sibling. This patch starts with the next CPU instead. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210804115857.6253-3-mgorman@techsingularity.net |
||
|
Mel Gorman
|
89aafd67f2 |
sched/fair: Use prev instead of new target as recent_used_cpu
After select_idle_sibling, p->recent_used_cpu is set to the new target. However on the next wakeup, prev will be the same as recent_used_cpu unless the load balancer has moved the task since the last wakeup. It still works, but is less efficient than it could be. This patch preserves recent_used_cpu for longer. The impact on SIS efficiency is tiny so the SIS statistic patches were used to track the hit rate for using recent_used_cpu. With perf bench pipe on a 2-socket Cascadelake machine, the hit rate went from 57.14% to 85.32%. For more intensive wakeup loads like hackbench, the hit rate is almost negligible but rose from 0.21% to 6.64%. For scaling loads like tbench, the hit rate goes from almost 0% to 25.42% overall. Broadly speaking, on tbench, the success rate is much higher for lower thread counts and drops to almost 0 as the workload scales to towards saturation. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210804115857.6253-2-mgorman@techsingularity.net |
||
|
Quentin Perret
|
7ad721bf10 |
sched: Don't report SCHED_FLAG_SUGOV in sched_getattr()
SCHED_FLAG_SUGOV is supposed to be a kernel-only flag that userspace cannot interact with. However, sched_getattr() currently reports it in sched_flags if called on a sugov worker even though it is not actually defined in a UAPI header. To avoid this, make sure to clean-up the sched_flags field in sched_getattr() before returning to userspace. Signed-off-by: Quentin Perret <qperret@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210727101103.2729607-3-qperret@google.com |
||
|
Quentin Perret
|
f95091536f |
sched/deadline: Fix reset_on_fork reporting of DL tasks
It is possible for sched_getattr() to incorrectly report the state of the reset_on_fork flag when called on a deadline task. Indeed, if the flag was set on a deadline task using sched_setattr() with flags (SCHED_FLAG_RESET_ON_FORK | SCHED_FLAG_KEEP_PARAMS), then p->sched_reset_on_fork will be set, but __setscheduler() will bail out early, which means that the dl_se->flags will not get updated by __setscheduler_params()->__setparam_dl(). Consequently, if sched_getattr() is then called on the task, __getparam_dl() will override kattr.sched_flags with the now out-of-date copy in dl_se->flags and report the stale value to userspace. To fix this, make sure to only copy the flags that are relevant to sched_deadline to and from the dl_se->flags field. Signed-off-by: Quentin Perret <qperret@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20210727101103.2729607-2-qperret@google.com |
||
Wang Hui
|
f912d05161 |
sched: remove redundant on_rq status change
activate_task/deactivate_task will change on_rq status, no need to do it again. Signed-off-by: Wang Hui <john.wanghui@huawei.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210721091109.1406043-1-john.wanghui@huawei.com |
||
Mika Penttilä
|
1c6829cfd3 |
sched/numa: Fix is_core_idle()
Use the loop variable instead of the function argument to test the
other SMT siblings for idle.
Fixes:
|
||
|
Peter Zijlstra
|
f558c2b834 |
sched/rt: Fix double enqueue caused by rt_effective_prio
Double enqueues in rt runqueues (list) have been reported while running
a simple test that spawns a number of threads doing a short sleep/run
pattern while being concurrently setscheduled between rt and fair class.
WARNING: CPU: 3 PID: 2825 at kernel/sched/rt.c:1294 enqueue_task_rt+0x355/0x360
CPU: 3 PID: 2825 Comm: setsched__13
RIP: 0010:enqueue_task_rt+0x355/0x360
Call Trace:
__sched_setscheduler+0x581/0x9d0
_sched_setscheduler+0x63/0xa0
do_sched_setscheduler+0xa0/0x150
__x64_sys_sched_setscheduler+0x1a/0x30
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
list_add double add: new=ffff9867cb629b40, prev=ffff9867cb629b40,
next=ffff98679fc67ca0.
kernel BUG at lib/list_debug.c:31!
invalid opcode: 0000 [#1] PREEMPT_RT SMP PTI
CPU: 3 PID: 2825 Comm: setsched__13
RIP: 0010:__list_add_valid+0x41/0x50
Call Trace:
enqueue_task_rt+0x291/0x360
__sched_setscheduler+0x581/0x9d0
_sched_setscheduler+0x63/0xa0
do_sched_setscheduler+0xa0/0x150
__x64_sys_sched_setscheduler+0x1a/0x30
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xae
__sched_setscheduler() uses rt_effective_prio() to handle proper queuing
of priority boosted tasks that are setscheduled while being boosted.
rt_effective_prio() is however called twice per each
__sched_setscheduler() call: first directly by __sched_setscheduler()
before dequeuing the task and then by __setscheduler() to actually do
the priority change. If the priority of the pi_top_task is concurrently
being changed however, it might happen that the two calls return
different results. If, for example, the first call returned the same rt
priority the task was running at and the second one a fair priority, the
task won't be removed by the rt list (on_list still set) and then
enqueued in the fair runqueue. When eventually setscheduled back to rt
it will be seen as enqueued already and the WARNING/BUG be issued.
Fix this by calling rt_effective_prio() only once and then reusing the
return value. While at it refactor code as well for clarity. Concurrent
priority inheritance handling is still safe and will eventually converge
to a new state by following the inheritance chain(s).
Fixes:
|
||
|
Linus Torvalds
|
877029d921 |
Three fixes:
- Fix load tracking bug/inconsistency - Fix a sporadic CFS bandwidth constraints enforcement bug - Fix a uclamp utilization tracking bug for newly woken tasks Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmDq8scRHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1i1nQ/+PsOimY0+2kW2EUp/a1a8h1ZHfyG1RjDo Kl/CCUDdEP0OuWC/cdnvYgo3hNPTVCpZvsIoR/t7CFinuR/ubfsFtLZ5juOzjk5v 2RjmSyOr0DbhUcO3GFKo+ABlrmiiJ9de89+oal+W/t/Zks/xqVHQ+f7HqSGvSd1f Lhem4U9UakbO3yjT/+VwSvNZgP8trtPQ6rrKw+yrwrxfjSo4D0Y+/3u/HCaYthIW 5i1+uBEXGnZaU7QhDfqqzbGcAKLRA+i2vBmNfbOyUeCcyKTsKlLwX9L1DlgNPLRP XvxVJWJcxwTsLbwVG1F3TvWw93iSLi34jPO//2ZnNppEhA4fjxmLSYV3uIsm8PUY /YmDdZ6fTW7ZIO/nhfcf3nS8Sp0UlfHXL9dV3mn2EzeMLGOKZY6vgAKdvEd+Fj+y J+VB01MgmVzGvFr9o1/ez3vWyk03CLDQuYMUo0yVcqAi4OLaArAz5vxXR/cF4PsB r69CCdSinMj2finaR39Eq0431Tpv71NDDfyqjVJEOk88Weszu6IACIOJCvpy0ZLQ LOA5kl2I8/mYEevnXgg9NPX8XO2iUFS1cVVNsRHUe4zqQZPPoBD6Oppb+kmfUQUe gABCZK217nkqFH4GdC9RCtRdnb4HO+6H15cLlDHjilECgGOPeJ8CPaK3pRvzv0g3 N2m4KcFI2j0= =FBcX -----END PGP SIGNATURE----- Merge tag 'sched-urgent-2021-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Three fixes: - Fix load tracking bug/inconsistency - Fix a sporadic CFS bandwidth constraints enforcement bug - Fix a uclamp utilization tracking bug for newly woken tasks" * tag 'sched-urgent-2021-07-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/uclamp: Ignore max aggregation if rq is idle sched/fair: Fix CFS bandwidth hrtimer expiry type sched/fair: Sync load_sum with load_avg after dequeue |
||
|
Linus Torvalds
|
aef4226f91 |
More power management updates for 5.14-rc1
- Drop the ->stop_cpu() (not really useful) and ->resolve_freq()
(unused) cpufreq driver callbacks and modify the users of the
former accordingly (Viresh Kumar, Rafael Wysocki).
- Add frequency invariance support to the ACPI CPPC cpufreq driver
again along with the related fixes and cleanups (Viresh Kumar).
- Update the Meditak, qcom and SCMI ARM cpufreq drivers (Fabien
Parent, Seiya Wang, Sibi Sankar, Christophe JAILLET).
- Rename black/white-lists in the DT cpufreq driver (Viresh Kumar).
- Add generic performance domains support to the dvfs DT bindings
(Sudeep Holla).
- Refine locking in the generic power domains (genpd) support code
to avoid lock dependency issues (Stephen Boyd).
- Update the MSM and qcom ARM cpuidle drivers (Bartosz Dudziak).
- Simplify the PM core debug code by using ktime_us_delta() to
compute time interval lengths (Mark-PK Tsai).
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Merge tag 'pm-5.14-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"These include cpufreq core simplifications and fixes, cpufreq driver
updates, cpuidle driver update, a generic power domains (genpd)
locking fix and a debug-related simplification of the PM core.
Specifics:
- Drop the ->stop_cpu() (not really useful) and ->resolve_freq()
(unused) cpufreq driver callbacks and modify the users of the
former accordingly (Viresh Kumar, Rafael Wysocki).
- Add frequency invariance support to the ACPI CPPC cpufreq driver
again along with the related fixes and cleanups (Viresh Kumar).
- Update the Meditak, qcom and SCMI ARM cpufreq drivers (Fabien
Parent, Seiya Wang, Sibi Sankar, Christophe JAILLET).
- Rename black/white-lists in the DT cpufreq driver (Viresh Kumar).
- Add generic performance domains support to the dvfs DT bindings
(Sudeep Holla).
- Refine locking in the generic power domains (genpd) support code to
avoid lock dependency issues (Stephen Boyd).
- Update the MSM and qcom ARM cpuidle drivers (Bartosz Dudziak).
- Simplify the PM core debug code by using ktime_us_delta() to
compute time interval lengths (Mark-PK Tsai)"
* tag 'pm-5.14-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (21 commits)
PM: domains: Shrink locking area of the gpd_list_lock
PM: sleep: Use ktime_us_delta() in initcall_debug_report()
cpufreq: CPPC: Add support for frequency invariance
arch_topology: Avoid use-after-free for scale_freq_data
cpufreq: CPPC: Pass structure instance by reference
cpufreq: CPPC: Fix potential memleak in cppc_cpufreq_cpu_init
cpufreq: Remove ->resolve_freq()
cpufreq: Reuse cpufreq_driver_resolve_freq() in __cpufreq_driver_target()
cpufreq: Remove the ->stop_cpu() driver callback
cpufreq: powernv: Migrate to ->exit() callback instead of ->stop_cpu()
cpufreq: CPPC: Migrate to ->exit() callback instead of ->stop_cpu()
cpufreq: intel_pstate: Combine ->stop_cpu() and ->offline()
cpuidle: qcom: Add SPM register data for MSM8226
dt-bindings: arm: msm: Add SAW2 for MSM8226
dt-bindings: cpufreq: update cpu type and clock name for MT8173 SoC
clk: mediatek: remove deprecated CLK_INFRA_CA57SEL for MT8173 SoC
cpufreq: dt: Rename black/white-lists
cpufreq: scmi: Fix an error message
cpufreq: mediatek: add support for mt8365
dt-bindings: dvfs: Add support for generic performance domains
...
|
||
Xuewen Yan
|
3e1493f463 |
sched/uclamp: Ignore max aggregation if rq is idle
When a task wakes up on an idle rq, uclamp_rq_util_with() would max
aggregate with rq value. But since there is no task enqueued yet, the
values are stale based on the last task that was running. When the new
task actually wakes up and enqueued, then the rq uclamp values should
reflect that of the newly woken up task effective uclamp values.
This is a problem particularly for uclamp_max because it default to
1024. If a task p with uclamp_max = 512 wakes up, then max aggregation
would ignore the capping that should apply when this task is enqueued,
which is wrong.
Fix that by ignoring max aggregation if the rq is idle since in that
case the effective uclamp value of the rq will be the ones of the task
that will wake up.
Fixes:
|
||
Odin Ugedal
|
72d0ad7cb5 |
sched/fair: Fix CFS bandwidth hrtimer expiry type
The time remaining until expiry of the refresh_timer can be negative. Casting the type to an unsigned 64-bit value will cause integer underflow, making the runtime_refresh_within return false instead of true. These situations are rare, but they do happen. This does not cause user-facing issues or errors; other than possibly unthrottling cfs_rq's using runtime from the previous period(s), making the CFS bandwidth enforcement less strict in those (special) situations. Signed-off-by: Odin Ugedal <odin@uged.al> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Link: https://lore.kernel.org/r/20210629121452.18429-1-odin@uged.al |
||
Vincent Guittot
|
ceb6ba45dc |
sched/fair: Sync load_sum with load_avg after dequeue
commit |
||
|
Linus Torvalds
|
3dbdb38e28 |
Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: - cgroup.kill is added which implements atomic killing of the whole subtree. Down the line, this should be able to replace the multiple userland implementations of "keep killing till empty". - PSI can now be turned off at boot time to avoid overhead for configurations which don't care about PSI. * 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: make per-cgroup pressure stall tracking configurable cgroup: Fix kernel-doc cgroup: inline cgroup_task_freeze() tests/cgroup: test cgroup.kill tests/cgroup: move cg_wait_for(), cg_prepare_for_wait() tests/cgroup: use cgroup.kill in cg_killall() docs/cgroup: add entry for cgroup.kill cgroup: introduce cgroup.kill |
||
Viresh Kumar
|
1eb5dde674 |
cpufreq: CPPC: Add support for frequency invariance
The Frequency Invariance Engine (FIE) is providing a frequency scaling correction factor that helps achieve more accurate load-tracking. Normally, this scaling factor can be obtained directly with the help of the cpufreq drivers as they know the exact frequency the hardware is running at. But that isn't the case for CPPC cpufreq driver. Another way of obtaining that is using the arch specific counter support, which is already present in kernel, but that hardware is optional for platforms. This patch updates the CPPC driver to register itself with the topology core to provide its own implementation (cppc_scale_freq_tick()) of topology_scale_freq_tick() which gets called by the scheduler on every tick. Note that the arch specific counters have higher priority than CPPC counters, if available, though the CPPC driver doesn't need to have any special handling for that. On an invocation of cppc_scale_freq_tick(), we schedule an irq work (since we reach here from hard-irq context), which then schedules a normal work item and cppc_scale_freq_workfn() updates the per_cpu arch_freq_scale variable based on the counter updates since the last tick. To allow platforms to disable this CPPC counter-based frequency invariance support, this is all done under CONFIG_ACPI_CPPC_CPUFREQ_FIE, which is enabled by default. This also exports sched_setattr_nocheck() as the CPPC driver can be built as a module. Cc: linux-acpi@vger.kernel.org Tested-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com> Tested-by: Qian Cai <quic_qiancai@quicinc.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> |
||
|
Linus Torvalds
|
a6eaf3850c |
- Fix a small inconsistency (bug) in load tracking, caught by a
new warning that several people reported. - Flip CONFIG_SCHED_CORE to default-disabled, and update the Kconfig help text. Signed-off-by: Ingo Molnar <mingo@kernel.org> -----BEGIN PGP SIGNATURE----- iQJFBAABCgAvFiEEBpT5eoXrXCwVQwEKEnMQ0APhK1gFAmDcSeURHG1pbmdvQGtl cm5lbC5vcmcACgkQEnMQ0APhK1g0ixAApwxCWCyNWKEKzg/I3FsR3RYfErpIUgnf gwQRtXNKZBOt/q8yWYw0VXG2ob17NgUdiC3p9IaxPrmCmB8tuojcsuPssHj5UktQ GWFoJdUwqQrM68Pl0centbN3xeKPcp7tHXK0jfmpbzolJxSFnx4/bQVPdhjlmWTM CoSTx4QCJoHYsNhZXj7aHQczKUMKBZ2/SD74+c/2Ft3jWkFmwdynzMdySKJfEuVX u/6PiFQDK0/5Qsic3a6pWmXZHcA0Q6HUwKKAaJcqI1OcAQyPuzwxY5qwbzvq5fRM ZhaJ7T5rJFQ8u6KndV5wv4+Xqgv6teAZBaPVP93cbnfeyVzWaiYL6/SC+xJnNDT+ fNpE41FINHq/NfUa6sId84lIpcQvAZzy3tpxS3VI/WXqDymFsG9BuoX9V2fm1uQP O3oa+B/PkP+VVezDS8qxZ2xixpcsRW97UVFtaj2P0QFOeb+qrOhPuSoCjNREkFmu CFWW+qnbiVaxQ3rtaXaHWhEtAhOMPbE4frYtbS4pjEMgv0K2E/mvDivHwrVX23II WkEQxUbzdp/APppBlhtFpcxKNTnNsV5Uk0VPhTu1bEOpKAC7wA+dmyPEMG0MLBUc 88DizVnofzKTax8PZnuabWpITcS+TS1qzBRmn1W1SajEh66iJltCSafWZ3JxytDO meqBYVd0ubQ= =Jgwc -----END PGP SIGNATURE----- Merge tag 'sched-urgent-2021-06-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: - Fix a small inconsistency (bug) in load tracking, caught by a new warning that several people reported. - Flip CONFIG_SCHED_CORE to default-disabled, and update the Kconfig help text. * tag 'sched-urgent-2021-06-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Disable CONFIG_SCHED_CORE by default sched/fair: Ensure _sum and _avg values stay consistent |
||
|
Linus Torvalds
|
df668a5fe4 |
for-5.14/block-2021-06-29
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||
|
Linus Torvalds
|
9269d27e51 |
Updates to the tick/nohz code in this cycle:
- Micro-optimize tick_nohz_full_cpu()
- Optimize idle exit tick restarts to be less eager
- Optimize tick_nohz_dep_set_task() to only wake up
a single CPU. This reduces IPIs and interruptions
on nohz_full CPUs.
- Optimize tick_nohz_dep_set_signal() in a similar
fashion.
- Skip IPIs in tick_nohz_kick_task() when trying
to kick a non-running task.
- Micro-optimize tick_nohz_task_switch() IRQ flags
handling to reduce context switching costs.
- Misc cleanups and fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'timers-nohz-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timers/nohz updates from Ingo Molnar:
- Micro-optimize tick_nohz_full_cpu()
- Optimize idle exit tick restarts to be less eager
- Optimize tick_nohz_dep_set_task() to only wake up a single CPU.
This reduces IPIs and interruptions on nohz_full CPUs.
- Optimize tick_nohz_dep_set_signal() in a similar fashion.
- Skip IPIs in tick_nohz_kick_task() when trying to kick a
non-running task.
- Micro-optimize tick_nohz_task_switch() IRQ flags handling to
reduce context switching costs.
- Misc cleanups and fixes
* tag 'timers-nohz-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MAINTAINERS: Add myself as context tracking maintainer
tick/nohz: Call tick_nohz_task_switch() with interrupts disabled
tick/nohz: Kick only _queued_ task whose tick dependency is updated
tick/nohz: Change signal tick dependency to wake up CPUs of member tasks
tick/nohz: Only wake up a single target cpu when kicking a task
tick/nohz: Update nohz_full Kconfig help
tick/nohz: Update idle_exittime on actual idle exit
tick/nohz: Remove superflous check for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
tick/nohz: Conditionally restart tick on idle exit
tick/nohz: Evaluate the CPU expression after the static key
|
||
|
Linus Torvalds
|
54a728dc5e |
Scheduler udpates for this cycle:
- Changes to core scheduling facilities:
- Add "Core Scheduling" via CONFIG_SCHED_CORE=y, which enables
coordinated scheduling across SMT siblings. This is a much
requested feature for cloud computing platforms, to allow
the flexible utilization of SMT siblings, without exposing
untrusted domains to information leaks & side channels, plus
to ensure more deterministic computing performance on SMT
systems used by heterogenous workloads.
There's new prctls to set core scheduling groups, which
allows more flexible management of workloads that can share
siblings.
- Fix task->state access anti-patterns that may result in missed
wakeups and rename it to ->__state in the process to catch new
abuses.
- Load-balancing changes:
- Tweak newidle_balance for fair-sched, to improve
'memcache'-like workloads.
- "Age" (decay) average idle time, to better track & improve workloads
such as 'tbench'.
- Fix & improve energy-aware (EAS) balancing logic & metrics.
- Fix & improve the uclamp metrics.
- Fix task migration (taskset) corner case on !CONFIG_CPUSET.
- Fix RT and deadline utilization tracking across policy changes
- Introduce a "burstable" CFS controller via cgroups, which allows
bursty CPU-bound workloads to borrow a bit against their future
quota to improve overall latencies & batching. Can be tweaked
via /sys/fs/cgroup/cpu/<X>/cpu.cfs_burst_us.
- Rework assymetric topology/capacity detection & handling.
- Scheduler statistics & tooling:
- Disable delayacct by default, but add a sysctl to enable
it at runtime if tooling needs it. Use static keys and
other optimizations to make it more palatable.
- Use sched_clock() in delayacct, instead of ktime_get_ns().
- Misc cleanups and fixes.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler udpates from Ingo Molnar:
- Changes to core scheduling facilities:
- Add "Core Scheduling" via CONFIG_SCHED_CORE=y, which enables
coordinated scheduling across SMT siblings. This is a much
requested feature for cloud computing platforms, to allow the
flexible utilization of SMT siblings, without exposing untrusted
domains to information leaks & side channels, plus to ensure more
deterministic computing performance on SMT systems used by
heterogenous workloads.
There are new prctls to set core scheduling groups, which allows
more flexible management of workloads that can share siblings.
- Fix task->state access anti-patterns that may result in missed
wakeups and rename it to ->__state in the process to catch new
abuses.
- Load-balancing changes:
- Tweak newidle_balance for fair-sched, to improve 'memcache'-like
workloads.
- "Age" (decay) average idle time, to better track & improve
workloads such as 'tbench'.
- Fix & improve energy-aware (EAS) balancing logic & metrics.
- Fix & improve the uclamp metrics.
- Fix task migration (taskset) corner case on !CONFIG_CPUSET.
- Fix RT and deadline utilization tracking across policy changes
- Introduce a "burstable" CFS controller via cgroups, which allows
bursty CPU-bound workloads to borrow a bit against their future
quota to improve overall latencies & batching. Can be tweaked via
/sys/fs/cgroup/cpu/<X>/cpu.cfs_burst_us.
- Rework assymetric topology/capacity detection & handling.
- Scheduler statistics & tooling:
- Disable delayacct by default, but add a sysctl to enable it at
runtime if tooling needs it. Use static keys and other
optimizations to make it more palatable.
- Use sched_clock() in delayacct, instead of ktime_get_ns().
- Misc cleanups and fixes.
* tag 'sched-core-2021-06-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
sched/doc: Update the CPU capacity asymmetry bits
sched/topology: Rework CPU capacity asymmetry detection
sched/core: Introduce SD_ASYM_CPUCAPACITY_FULL sched_domain flag
psi: Fix race between psi_trigger_create/destroy
sched/fair: Introduce the burstable CFS controller
sched/uclamp: Fix uclamp_tg_restrict()
sched/rt: Fix Deadline utilization tracking during policy change
sched/rt: Fix RT utilization tracking during policy change
sched: Change task_struct::state
sched,arch: Remove unused TASK_STATE offsets
sched,timer: Use __set_current_state()
sched: Add get_current_state()
sched,perf,kvm: Fix preemption condition
sched: Introduce task_is_running()
sched: Unbreak wakeups
sched/fair: Age the average idle time
sched/cpufreq: Consider reduced CPU capacity in energy calculation
sched/fair: Take thermal pressure into account while estimating energy
thermal/cpufreq_cooling: Update offline CPUs per-cpu thermal_pressure
sched/fair: Return early from update_tg_cfs_load() if delta == 0
...
|
||
Yuan ZhaoXiong
|
031e3bd898 |
sched: Optimize housekeeping_cpumask() in for_each_cpu_and()
On a 128 cores AMD machine, there are 8 cores in nohz_full mode, and
the others are used for housekeeping. When many housekeeping cpus are
in idle state, we can observe huge time burn in the loop for searching
nearest busy housekeeper cpu by ftrace.
9) | get_nohz_timer_target() {
9) | housekeeping_test_cpu() {
9) 0.390 us | housekeeping_get_mask.part.1();
9) 0.561 us | }
9) 0.090 us | __rcu_read_lock();
9) 0.090 us | housekeeping_cpumask();
9) 0.521 us | housekeeping_cpumask();
9) 0.140 us | housekeeping_cpumask();
...
9) 0.500 us | housekeeping_cpumask();
9) | housekeeping_any_cpu() {
9) 0.090 us | housekeeping_get_mask.part.1();
9) 0.100 us | sched_numa_find_closest();
9) 0.491 us | }
9) 0.100 us | __rcu_read_unlock();
9) + 76.163 us | }
for_each_cpu_and() is a micro function, so in get_nohz_timer_target()
function the
for_each_cpu_and(i, sched_domain_span(sd),
housekeeping_cpumask(HK_FLAG_TIMER))
equals to below:
for (i = -1; i = cpumask_next_and(i, sched_domain_span(sd),
housekeeping_cpumask(HK_FLAG_TIMER)), i < nr_cpu_ids;)
That will cause that housekeeping_cpumask() will be invoked many times.
The housekeeping_cpumask() function returns a const value, so it is
unnecessary to invoke it every time. This patch can minimize the worst
searching time from ~76us to ~16us in my testing.
Similarly, the find_new_ilb() function has the same problem.
Co-developed-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Yuan ZhaoXiong <yuanzhaoxiong@baidu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1622985115-51007-1-git-send-email-yuanzhaoxiong@baidu.com
|
||
Hailong Liu
|
18765447c3 |
sched/sysctl: Move extern sysctl declarations to sched.h
Since commit '8a99b6833c88(sched: Move SCHED_DEBUG sysctl to debugfs)', SCHED_DEBUG sysctls are moved to debugfs, so these extern sysctls in include/linux/sched/sysctl.h are no longer needed for sysctl.c, even some are no longer needed. So move those extern sysctls that needed by kernel/sched/debug.c to kernel/sched/sched.h, and remove others that are no longer needed. Signed-off-by: Hailong Liu <liu.hailong6@zte.com.cn> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210606115451.26745-1-liuhailongg6@163.com |