[GIT PULL] Scheduler enhancements for v6.14

[GIT PULL] Scheduler enhancements for v6.14

[Ingo Molnar]

Linus,

Please pull the latest sched/core Git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-20

   # HEAD: 7d9da040575b343085287686fa902a5b2d43c7ca psi: Fix race when task wakes up before psi_sched_switch() adjusts flags

Scheduler enhancements for v6.14:

 - Fair scheduler (SCHED_FAIR) enhancements:

   - Behavioral improvements:
     - Untangle NEXT_BUDDY and pick_next_task() (Peter Zijlstra)

   - Delayed-dequeue enhancements & fixes: (Vincent Guittot)

     - Rename h_nr_running into h_nr_queued
     - Add new cfs_rq.h_nr_runnable
     - Use the new cfs_rq.h_nr_runnable
     - Removed unsued cfs_rq.h_nr_delayed
     - Rename cfs_rq.idle_h_nr_running into h_nr_idle
     - Remove unused cfs_rq.idle_nr_running
     - Rename cfs_rq.nr_running into nr_queued
     - Do not try to migrate delayed dequeue task
     - Fix variable declaration position
     - Encapsulate set custom slice in a __setparam_fair() function

   - Fixes:
     - Fix race between yield_to() and try_to_wake_up() (Tianchen Ding)
     - Fix CPU bandwidth limit bypass during CPU hotplug (Vishal Chourasia)

   - Cleanups:
     - Clean up in migrate_degrades_locality() to improve
       readability (Peter Zijlstra)
     - Mark m*_vruntime() with __maybe_unused (Andy Shevchenko)
     - Update comments after sched_tick() rename (Sebastian Andrzej Siewior)
     - Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()
       (Valentin Schneider)

 - Deadline scheduler (SCHED_DL) enhancements:

   - Restore dl_server bandwidth on non-destructive root domain
     changes (Juri Lelli)

   - Correctly account for allocated bandwidth during
     hotplug (Juri Lelli)

   - Check bandwidth overflow earlier for hotplug (Juri Lelli)

   - Clean up goto label in pick_earliest_pushable_dl_task()
     (John Stultz)

   - Consolidate timer cancellation (Wander Lairson Costa)

 - Load-balancer enhancements:

   - Improve performance by prioritizing migrating eligible
     tasks in sched_balance_rq() (Hao Jia)

   - Do not compute NUMA Balancing stats unnecessarily during
     load-balancing (K Prateek Nayak)

   - Do not compute overloaded status unnecessarily during
     load-balancing (K Prateek Nayak)

 - Generic scheduling code enhancements:

   - Use READ_ONCE() in task_on_rq_queued(), to consistently use
     the WRITE_ONCE() updated ->on_rq field (Harshit Agarwal)

 - Isolated CPUs support enhancements: (Waiman Long)

   - Make "isolcpus=nohz" equivalent to "nohz_full"
   - Consolidate housekeeping cpumasks that are always identical
   - Remove HK_TYPE_SCHED
   - Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

 - RSEQ enhancements:

   - Validate read-only fields under DEBUG_RSEQ config
     (Mathieu Desnoyers)

 - PSI enhancements:

   - Fix race when task wakes up before psi_sched_switch()
     adjusts flags (Chengming Zhou)

 - IRQ time accounting performance enhancements: (Yafang Shao)

   - Define sched_clock_irqtime as static key
   - Don't account irq time if sched_clock_irqtime is disabled

 - Virtual machine scheduling enhancements:

   - Don't try to catch up excess steal time (Suleiman Souhlal)

 - Heterogenous x86 CPU scheduling enhancements: (K Prateek Nayak)

   - Convert "sysctl_sched_itmt_enabled" to boolean
   - Use guard() for itmt_update_mutex
   - Move the "sched_itmt_enabled" sysctl to debugfs
   - Remove x86_smt_flags and use cpu_smt_flags directly
   - Use x86_sched_itmt_flags for PKG domain unconditionally

 - Debugging code & instrumentation enhancements:

   - Change need_resched warnings to pr_err() (David Rientjes)
   - Print domain name in /proc/schedstat (K Prateek Nayak)
   - Fix value reported by hot tasks pulled in /proc/schedstat (Peter Zijlstra)
   - Report the different kinds of imbalances in /proc/schedstat (Swapnil Sapkal)
   - Move sched domain name out of CONFIG_SCHED_DEBUG (Swapnil Sapkal)
   - Update Schedstat version to 17 (Swapnil Sapkal)

 Thanks,

	Ingo

------------------>
Andy Shevchenko (1):
      sched/fair: Mark m*_vruntime() with __maybe_unused

Chengming Zhou (1):
      psi: Fix race when task wakes up before psi_sched_switch() adjusts flags

David Rientjes (1):
      sched/debug: Change need_resched warnings to pr_err

Hao Jia (1):
      sched/core: Prioritize migrating eligible tasks in sched_balance_rq()

Harshit Agarwal (1):
      sched: add READ_ONCE to task_on_rq_queued

John Stultz (1):
      sched: deadline: Cleanup goto label in pick_earliest_pushable_dl_task

Juri Lelli (3):
      sched/deadline: Restore dl_server bandwidth on non-destructive root domain changes
      sched/deadline: Correctly account for allocated bandwidth during hotplug
      sched/deadline: Check bandwidth overflow earlier for hotplug

K Prateek Nayak (8):
      sched/stats: Print domain name in /proc/schedstat
      x86/itmt: Convert "sysctl_sched_itmt_enabled" to boolean
      x86/itmt: Use guard() for itmt_update_mutex
      x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs
      x86/topology: Remove x86_smt_flags and use cpu_smt_flags directly
      x86/topology: Use x86_sched_itmt_flags for PKG domain unconditionally
      sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb
      sched/fair: Do not compute overloaded status unnecessarily during lb

Mathieu Desnoyers (1):
      rseq: Validate read-only fields under DEBUG_RSEQ config

Peter Zijlstra (3):
      sched/fair: Untangle NEXT_BUDDY and pick_next_task()
      sched/fair: Fix value reported by hot tasks pulled in /proc/schedstat
      sched/fair: Cleanup in migrate_degrades_locality() to improve readability

Sebastian Andrzej Siewior (1):
      sched/fair: Update comments after sched_tick() rename.

Suleiman Souhlal (1):
      sched: Don't try to catch up excess steal time.

Swapnil Sapkal (3):
      sched: Report the different kinds of imbalances in /proc/schedstat
      sched: Move sched domain name out of CONFIG_SCHED_DEBUG
      docs: Update Schedstat version to 17

Tianchen Ding (1):
      sched: Fix race between yield_to() and try_to_wake_up()

Valentin Schneider (1):
      sched/fair: Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()

Vincent Guittot (10):
      sched/fair: Rename h_nr_running into h_nr_queued
      sched/fair: Add new cfs_rq.h_nr_runnable
      sched/fair: Use the new cfs_rq.h_nr_runnable
      sched/fair: Removed unsued cfs_rq.h_nr_delayed
      sched/fair: Rename cfs_rq.idle_h_nr_running into h_nr_idle
      sched/fair: Remove unused cfs_rq.idle_nr_running
      sched/fair: Rename cfs_rq.nr_running into nr_queued
      sched/fair: Do not try to migrate delayed dequeue task
      sched/fair: Fix variable declaration position
      sched/fair: Encapsulate set custom slice in a __setparam_fair() function

Vishal Chourasia (1):
      sched/fair: Fix CPU bandwidth limit bypass during CPU hotplug

Waiman Long (4):
      sched/core: Remove HK_TYPE_SCHED
      sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
      sched/isolation: Consolidate housekeeping cpumasks that are always identical
      sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

Wander Lairson Costa (1):
      sched/deadline: Consolidate Timer Cancellation

Yafang Shao (3):
      sched: Define sched_clock_irqtime as static key
      sched: Don't account irq time if sched_clock_irqtime is disabled
      sched, psi: Don't account irq time if sched_clock_irqtime is disabled


 Documentation/admin-guide/kernel-parameters.txt |   4 +-
 Documentation/scheduler/sched-stats.rst         | 126 ++++---
 arch/x86/include/asm/topology.h                 |   4 +-
 arch/x86/kernel/itmt.c                          |  81 ++---
 arch/x86/kernel/smpboot.c                       |  19 +-
 include/linux/sched.h                           |  10 +
 include/linux/sched/isolation.h                 |  21 +-
 include/linux/sched/topology.h                  |  13 +-
 kernel/rseq.c                                   |  98 ++++++
 kernel/sched/core.c                             |  94 +++--
 kernel/sched/cputime.c                          |  16 +-
 kernel/sched/deadline.c                         | 119 +++++--
 kernel/sched/debug.c                            |  25 +-
 kernel/sched/fair.c                             | 444 ++++++++++++++----------
 kernel/sched/features.h                         |   9 +
 kernel/sched/isolation.c                        |  22 +-
 kernel/sched/pelt.c                             |   4 +-
 kernel/sched/psi.c                              |   7 +-
 kernel/sched/sched.h                            |  37 +-
 kernel/sched/stats.c                            |  11 +-
 kernel/sched/stats.h                            |   4 +
 kernel/sched/syscalls.c                         |  18 +-
 kernel/sched/topology.c                         |  12 +-
 23 files changed, 720 insertions(+), 478 deletions(-)

Re: [GIT PULL] Scheduler enhancements for v6.14

[Mathieu Desnoyers]

On 20-Jan-2025 12:07:41 PM, Ingo Molnar wrote:
> 
> Linus,
> 
> Please pull the latest sched/core Git tree from:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-20
> 
>    # HEAD: 7d9da040575b343085287686fa902a5b2d43c7ca psi: Fix race when task wakes up before psi_sched_switch() adjusts flags
> 
> Scheduler enhancements for v6.14:

[...]

>  - RSEQ enhancements:
> 
>    - Validate read-only fields under DEBUG_RSEQ config
>      (Mathieu Desnoyers)

FYI, a regression introduced by this commit was reported by s390x
glibc developers testing against linux-next:

https://sourceware.org/pipermail/libc-alpha/2025-January/163993.html

I've sent a fix here:

https://lore.kernel.org/lkml/20250116205956.836074-1-mathieu.desnoyers@efficios.com/

The commit introducing the issue is in this PR, but not the fix.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

[GIT PULL v2] Scheduler enhancements for v6.14

[Ingo Molnar]

* Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> On 20-Jan-2025 12:07:41 PM, Ingo Molnar wrote:
> > 
> > Linus,
> > 
> > Please pull the latest sched/core Git tree from:
> > 
> >    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-20
> > 
> >    # HEAD: 7d9da040575b343085287686fa902a5b2d43c7ca psi: Fix race when task wakes up before psi_sched_switch() adjusts flags
> > 
> > Scheduler enhancements for v6.14:
> 
> [...]
> 
> >  - RSEQ enhancements:
> > 
> >    - Validate read-only fields under DEBUG_RSEQ config
> >      (Mathieu Desnoyers)
> 
> FYI, a regression introduced by this commit was reported by s390x
> glibc developers testing against linux-next:
> 
> https://sourceware.org/pipermail/libc-alpha/2025-January/163993.html
> 
> I've sent a fix here:
> 
> https://lore.kernel.org/lkml/20250116205956.836074-1-mathieu.desnoyers@efficios.com/
> 
> The commit introducing the issue is in this PR, but not the fix.

Indeed - with the bug RSEQ_FLAG_UNREGISTER would fail with an incorrect 
-EFAULT return.

I've applied your fix, and updated the pull request for Linus further 
below. If Linus has already pulled I'll send a fixes pull request 
separately, or Linus can apply the fix from email directly:

  Acked-by: Ingo Molnar <mingo@kernel.org>

Or he can pull the sched-core-2025-01-21 tag below safely on top of 
sched-core-2025-01-20, which will result in a diffstat of:

  Mathieu Desnoyers (1):
      rseq: Fix rseq unregistration regression

  kernel/rseq.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

Since I booted the scheduler tree on generic desktops and it was tested 
on other systems as well and nothing appeared to be broken, I presume 
RSEQ_FLAG_UNREGISTER is used only in libc syscall-testcases and in 
specific applications?

Thanks,

	Ingo

===================================>
Linus,

Please pull the latest sched/core Git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-21

   # HEAD: 40724ecafccb1fb62b66264854e8c3ad394c8f3d rseq: Fix rseq unregistration regression

Scheduler enhancements for v6.14:

 - Fair scheduler (SCHED_FAIR) enhancements:

   - Behavioral improvements:
     - Untangle NEXT_BUDDY and pick_next_task() (Peter Zijlstra)

   - Delayed-dequeue enhancements & fixes: (Vincent Guittot)

     - Rename h_nr_running into h_nr_queued
     - Add new cfs_rq.h_nr_runnable
     - Use the new cfs_rq.h_nr_runnable
     - Removed unsued cfs_rq.h_nr_delayed
     - Rename cfs_rq.idle_h_nr_running into h_nr_idle
     - Remove unused cfs_rq.idle_nr_running
     - Rename cfs_rq.nr_running into nr_queued
     - Do not try to migrate delayed dequeue task
     - Fix variable declaration position
     - Encapsulate set custom slice in a __setparam_fair() function

   - Fixes:
     - Fix race between yield_to() and try_to_wake_up() (Tianchen Ding)
     - Fix CPU bandwidth limit bypass during CPU hotplug (Vishal Chourasia)

   - Cleanups:
     - Clean up in migrate_degrades_locality() to improve
       readability (Peter Zijlstra)
     - Mark m*_vruntime() with __maybe_unused (Andy Shevchenko)
     - Update comments after sched_tick() rename (Sebastian Andrzej Siewior)
     - Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()
       (Valentin Schneider)

 - Deadline scheduler (SCHED_DL) enhancements:

   - Restore dl_server bandwidth on non-destructive root domain
     changes (Juri Lelli)

   - Correctly account for allocated bandwidth during
     hotplug (Juri Lelli)

   - Check bandwidth overflow earlier for hotplug (Juri Lelli)

   - Clean up goto label in pick_earliest_pushable_dl_task()
     (John Stultz)

   - Consolidate timer cancellation (Wander Lairson Costa)

 - Load-balancer enhancements:

   - Improve performance by prioritizing migrating eligible
     tasks in sched_balance_rq() (Hao Jia)

   - Do not compute NUMA Balancing stats unnecessarily during
     load-balancing (K Prateek Nayak)

   - Do not compute overloaded status unnecessarily during
     load-balancing (K Prateek Nayak)

 - Generic scheduling code enhancements:

   - Use READ_ONCE() in task_on_rq_queued(), to consistently use
     the WRITE_ONCE() updated ->on_rq field (Harshit Agarwal)

 - Isolated CPUs support enhancements: (Waiman Long)

   - Make "isolcpus=nohz" equivalent to "nohz_full"
   - Consolidate housekeeping cpumasks that are always identical
   - Remove HK_TYPE_SCHED
   - Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

 - RSEQ enhancements:

   - Validate read-only fields under DEBUG_RSEQ config
     (Mathieu Desnoyers)

 - PSI enhancements:

   - Fix race when task wakes up before psi_sched_switch()
     adjusts flags (Chengming Zhou)

 - IRQ time accounting performance enhancements: (Yafang Shao)

   - Define sched_clock_irqtime as static key
   - Don't account irq time if sched_clock_irqtime is disabled

 - Virtual machine scheduling enhancements:

   - Don't try to catch up excess steal time (Suleiman Souhlal)

 - Heterogenous x86 CPU scheduling enhancements: (K Prateek Nayak)

   - Convert "sysctl_sched_itmt_enabled" to boolean
   - Use guard() for itmt_update_mutex
   - Move the "sched_itmt_enabled" sysctl to debugfs
   - Remove x86_smt_flags and use cpu_smt_flags directly
   - Use x86_sched_itmt_flags for PKG domain unconditionally

 - Debugging code & instrumentation enhancements:

   - Change need_resched warnings to pr_err() (David Rientjes)
   - Print domain name in /proc/schedstat (K Prateek Nayak)
   - Fix value reported by hot tasks pulled in /proc/schedstat (Peter Zijlstra)
   - Report the different kinds of imbalances in /proc/schedstat (Swapnil Sapkal)
   - Move sched domain name out of CONFIG_SCHED_DEBUG (Swapnil Sapkal)
   - Update Schedstat version to 17 (Swapnil Sapkal)

 Thanks,

	Ingo

------------------>
Andy Shevchenko (1):
      sched/fair: Mark m*_vruntime() with __maybe_unused

Chengming Zhou (1):
      psi: Fix race when task wakes up before psi_sched_switch() adjusts flags

David Rientjes (1):
      sched/debug: Change need_resched warnings to pr_err

Hao Jia (1):
      sched/core: Prioritize migrating eligible tasks in sched_balance_rq()

Harshit Agarwal (1):
      sched: add READ_ONCE to task_on_rq_queued

John Stultz (1):
      sched: deadline: Cleanup goto label in pick_earliest_pushable_dl_task

Juri Lelli (3):
      sched/deadline: Restore dl_server bandwidth on non-destructive root domain changes
      sched/deadline: Correctly account for allocated bandwidth during hotplug
      sched/deadline: Check bandwidth overflow earlier for hotplug

K Prateek Nayak (8):
      sched/stats: Print domain name in /proc/schedstat
      x86/itmt: Convert "sysctl_sched_itmt_enabled" to boolean
      x86/itmt: Use guard() for itmt_update_mutex
      x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs
      x86/topology: Remove x86_smt_flags and use cpu_smt_flags directly
      x86/topology: Use x86_sched_itmt_flags for PKG domain unconditionally
      sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb
      sched/fair: Do not compute overloaded status unnecessarily during lb

Mathieu Desnoyers (2):
      rseq: Validate read-only fields under DEBUG_RSEQ config
      rseq: Fix rseq unregistration regression

Peter Zijlstra (3):
      sched/fair: Untangle NEXT_BUDDY and pick_next_task()
      sched/fair: Fix value reported by hot tasks pulled in /proc/schedstat
      sched/fair: Cleanup in migrate_degrades_locality() to improve readability

Sebastian Andrzej Siewior (1):
      sched/fair: Update comments after sched_tick() rename.

Suleiman Souhlal (1):
      sched: Don't try to catch up excess steal time.

Swapnil Sapkal (3):
      sched: Report the different kinds of imbalances in /proc/schedstat
      sched: Move sched domain name out of CONFIG_SCHED_DEBUG
      docs: Update Schedstat version to 17

Tianchen Ding (1):
      sched: Fix race between yield_to() and try_to_wake_up()

Valentin Schneider (1):
      sched/fair: Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()

Vincent Guittot (10):
      sched/fair: Rename h_nr_running into h_nr_queued
      sched/fair: Add new cfs_rq.h_nr_runnable
      sched/fair: Use the new cfs_rq.h_nr_runnable
      sched/fair: Removed unsued cfs_rq.h_nr_delayed
      sched/fair: Rename cfs_rq.idle_h_nr_running into h_nr_idle
      sched/fair: Remove unused cfs_rq.idle_nr_running
      sched/fair: Rename cfs_rq.nr_running into nr_queued
      sched/fair: Do not try to migrate delayed dequeue task
      sched/fair: Fix variable declaration position
      sched/fair: Encapsulate set custom slice in a __setparam_fair() function

Vishal Chourasia (1):
      sched/fair: Fix CPU bandwidth limit bypass during CPU hotplug

Waiman Long (4):
      sched/core: Remove HK_TYPE_SCHED
      sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
      sched/isolation: Consolidate housekeeping cpumasks that are always identical
      sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

Wander Lairson Costa (1):
      sched/deadline: Consolidate Timer Cancellation

Yafang Shao (3):
      sched: Define sched_clock_irqtime as static key
      sched: Don't account irq time if sched_clock_irqtime is disabled
      sched, psi: Don't account irq time if sched_clock_irqtime is disabled


 Documentation/admin-guide/kernel-parameters.txt |   4 +-
 Documentation/scheduler/sched-stats.rst         | 126 ++++---
 arch/x86/include/asm/topology.h                 |   4 +-
 arch/x86/kernel/itmt.c                          |  81 ++---
 arch/x86/kernel/smpboot.c                       |  19 +-
 include/linux/sched.h                           |  10 +
 include/linux/sched/isolation.h                 |  21 +-
 include/linux/sched/topology.h                  |  13 +-
 kernel/rseq.c                                   |  98 ++++++
 kernel/sched/core.c                             |  94 +++--
 kernel/sched/cputime.c                          |  16 +-
 kernel/sched/deadline.c                         | 119 +++++--
 kernel/sched/debug.c                            |  25 +-
 kernel/sched/fair.c                             | 444 ++++++++++++++----------
 kernel/sched/features.h                         |   9 +
 kernel/sched/isolation.c                        |  22 +-
 kernel/sched/pelt.c                             |   4 +-
 kernel/sched/psi.c                              |   7 +-
 kernel/sched/sched.h                            |  37 +-
 kernel/sched/stats.c                            |  11 +-
 kernel/sched/stats.h                            |   4 +
 kernel/sched/syscalls.c                         |  18 +-
 kernel/sched/topology.c                         |  12 +-
 23 files changed, 720 insertions(+), 478 deletions(-)

Re: [GIT PULL v2] Scheduler enhancements for v6.14

[Mathieu Desnoyers]

On 2025-01-21 02:23, Ingo Molnar wrote:
> 
> * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> 
>> On 20-Jan-2025 12:07:41 PM, Ingo Molnar wrote:
>>>
>>> Linus,
>>>
>>> Please pull the latest sched/core Git tree from:
>>>
>>>     git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-20
>>>
>>>     # HEAD: 7d9da040575b343085287686fa902a5b2d43c7ca psi: Fix race when task wakes up before psi_sched_switch() adjusts flags
>>>
>>> Scheduler enhancements for v6.14:
>>
>> [...]
>>
>>>   - RSEQ enhancements:
>>>
>>>     - Validate read-only fields under DEBUG_RSEQ config
>>>       (Mathieu Desnoyers)
>>
>> FYI, a regression introduced by this commit was reported by s390x
>> glibc developers testing against linux-next:
>>
>> https://sourceware.org/pipermail/libc-alpha/2025-January/163993.html
>>
>> I've sent a fix here:
>>
>> https://lore.kernel.org/lkml/20250116205956.836074-1-mathieu.desnoyers@efficios.com/
>>
>> The commit introducing the issue is in this PR, but not the fix.
> 
> Indeed - with the bug RSEQ_FLAG_UNREGISTER would fail with an incorrect
> -EFAULT return.
> 
> I've applied your fix, and updated the pull request for Linus further
> below. If Linus has already pulled I'll send a fixes pull request
> separately, or Linus can apply the fix from email directly:
> 
>    Acked-by: Ingo Molnar <mingo@kernel.org>
> 
> Or he can pull the sched-core-2025-01-21 tag below safely on top of
> sched-core-2025-01-20, which will result in a diffstat of:
> 
>    Mathieu Desnoyers (1):
>        rseq: Fix rseq unregistration regression
> 
>    kernel/rseq.c | 2 +-
>    1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Since I booted the scheduler tree on generic desktops and it was tested
> on other systems as well and nothing appeared to be broken, I presume
> RSEQ_FLAG_UNREGISTER is used only in libc syscall-testcases and in
> specific applications?

Nowadays, rseq unregistration is used by specialized applications (e.g.
tcmalloc) which disable glibc rseq support with the glibc tunable
and register it themselves. (GLIBC_TUNABLES=glibc.pthread.rseq=0)

A recent glibc (2.35+) don't use explicit rseq unregistration, it's
unregistered implicitly when the thread exits.

I'll make a note to add a test case for GLIBC_TUNABLES=glibc.pthread.rseq=0
in the rseq selftests and librseq to improve test coverage when using a
recent glibc.

We have all the code in there to use rseq unregistration, but it is skipped
when glibc 2.35+ is handling the registration.

Thanks,

Mathieu

> 
> Thanks,
> 
> 	Ingo
> 
> ===================================>
> Linus,
> 
> Please pull the latest sched/core Git tree from:
> 
>     git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-21
> 
>     # HEAD: 40724ecafccb1fb62b66264854e8c3ad394c8f3d rseq: Fix rseq unregistration regression
> 
> Scheduler enhancements for v6.14:
> 
>   - Fair scheduler (SCHED_FAIR) enhancements:
> 
>     - Behavioral improvements:
>       - Untangle NEXT_BUDDY and pick_next_task() (Peter Zijlstra)
> 
>     - Delayed-dequeue enhancements & fixes: (Vincent Guittot)
> 
>       - Rename h_nr_running into h_nr_queued
>       - Add new cfs_rq.h_nr_runnable
>       - Use the new cfs_rq.h_nr_runnable
>       - Removed unsued cfs_rq.h_nr_delayed
>       - Rename cfs_rq.idle_h_nr_running into h_nr_idle
>       - Remove unused cfs_rq.idle_nr_running
>       - Rename cfs_rq.nr_running into nr_queued
>       - Do not try to migrate delayed dequeue task
>       - Fix variable declaration position
>       - Encapsulate set custom slice in a __setparam_fair() function
> 
>     - Fixes:
>       - Fix race between yield_to() and try_to_wake_up() (Tianchen Ding)
>       - Fix CPU bandwidth limit bypass during CPU hotplug (Vishal Chourasia)
> 
>     - Cleanups:
>       - Clean up in migrate_degrades_locality() to improve
>         readability (Peter Zijlstra)
>       - Mark m*_vruntime() with __maybe_unused (Andy Shevchenko)
>       - Update comments after sched_tick() rename (Sebastian Andrzej Siewior)
>       - Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()
>         (Valentin Schneider)
> 
>   - Deadline scheduler (SCHED_DL) enhancements:
> 
>     - Restore dl_server bandwidth on non-destructive root domain
>       changes (Juri Lelli)
> 
>     - Correctly account for allocated bandwidth during
>       hotplug (Juri Lelli)
> 
>     - Check bandwidth overflow earlier for hotplug (Juri Lelli)
> 
>     - Clean up goto label in pick_earliest_pushable_dl_task()
>       (John Stultz)
> 
>     - Consolidate timer cancellation (Wander Lairson Costa)
> 
>   - Load-balancer enhancements:
> 
>     - Improve performance by prioritizing migrating eligible
>       tasks in sched_balance_rq() (Hao Jia)
> 
>     - Do not compute NUMA Balancing stats unnecessarily during
>       load-balancing (K Prateek Nayak)
> 
>     - Do not compute overloaded status unnecessarily during
>       load-balancing (K Prateek Nayak)
> 
>   - Generic scheduling code enhancements:
> 
>     - Use READ_ONCE() in task_on_rq_queued(), to consistently use
>       the WRITE_ONCE() updated ->on_rq field (Harshit Agarwal)
> 
>   - Isolated CPUs support enhancements: (Waiman Long)
> 
>     - Make "isolcpus=nohz" equivalent to "nohz_full"
>     - Consolidate housekeeping cpumasks that are always identical
>     - Remove HK_TYPE_SCHED
>     - Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE
> 
>   - RSEQ enhancements:
> 
>     - Validate read-only fields under DEBUG_RSEQ config
>       (Mathieu Desnoyers)
> 
>   - PSI enhancements:
> 
>     - Fix race when task wakes up before psi_sched_switch()
>       adjusts flags (Chengming Zhou)
> 
>   - IRQ time accounting performance enhancements: (Yafang Shao)
> 
>     - Define sched_clock_irqtime as static key
>     - Don't account irq time if sched_clock_irqtime is disabled
> 
>   - Virtual machine scheduling enhancements:
> 
>     - Don't try to catch up excess steal time (Suleiman Souhlal)
> 
>   - Heterogenous x86 CPU scheduling enhancements: (K Prateek Nayak)
> 
>     - Convert "sysctl_sched_itmt_enabled" to boolean
>     - Use guard() for itmt_update_mutex
>     - Move the "sched_itmt_enabled" sysctl to debugfs
>     - Remove x86_smt_flags and use cpu_smt_flags directly
>     - Use x86_sched_itmt_flags for PKG domain unconditionally
> 
>   - Debugging code & instrumentation enhancements:
> 
>     - Change need_resched warnings to pr_err() (David Rientjes)
>     - Print domain name in /proc/schedstat (K Prateek Nayak)
>     - Fix value reported by hot tasks pulled in /proc/schedstat (Peter Zijlstra)
>     - Report the different kinds of imbalances in /proc/schedstat (Swapnil Sapkal)
>     - Move sched domain name out of CONFIG_SCHED_DEBUG (Swapnil Sapkal)
>     - Update Schedstat version to 17 (Swapnil Sapkal)
> 
>   Thanks,
> 
> 	Ingo
> 
> ------------------>
> Andy Shevchenko (1):
>        sched/fair: Mark m*_vruntime() with __maybe_unused
> 
> Chengming Zhou (1):
>        psi: Fix race when task wakes up before psi_sched_switch() adjusts flags
> 
> David Rientjes (1):
>        sched/debug: Change need_resched warnings to pr_err
> 
> Hao Jia (1):
>        sched/core: Prioritize migrating eligible tasks in sched_balance_rq()
> 
> Harshit Agarwal (1):
>        sched: add READ_ONCE to task_on_rq_queued
> 
> John Stultz (1):
>        sched: deadline: Cleanup goto label in pick_earliest_pushable_dl_task
> 
> Juri Lelli (3):
>        sched/deadline: Restore dl_server bandwidth on non-destructive root domain changes
>        sched/deadline: Correctly account for allocated bandwidth during hotplug
>        sched/deadline: Check bandwidth overflow earlier for hotplug
> 
> K Prateek Nayak (8):
>        sched/stats: Print domain name in /proc/schedstat
>        x86/itmt: Convert "sysctl_sched_itmt_enabled" to boolean
>        x86/itmt: Use guard() for itmt_update_mutex
>        x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs
>        x86/topology: Remove x86_smt_flags and use cpu_smt_flags directly
>        x86/topology: Use x86_sched_itmt_flags for PKG domain unconditionally
>        sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb
>        sched/fair: Do not compute overloaded status unnecessarily during lb
> 
> Mathieu Desnoyers (2):
>        rseq: Validate read-only fields under DEBUG_RSEQ config
>        rseq: Fix rseq unregistration regression
> 
> Peter Zijlstra (3):
>        sched/fair: Untangle NEXT_BUDDY and pick_next_task()
>        sched/fair: Fix value reported by hot tasks pulled in /proc/schedstat
>        sched/fair: Cleanup in migrate_degrades_locality() to improve readability
> 
> Sebastian Andrzej Siewior (1):
>        sched/fair: Update comments after sched_tick() rename.
> 
> Suleiman Souhlal (1):
>        sched: Don't try to catch up excess steal time.
> 
> Swapnil Sapkal (3):
>        sched: Report the different kinds of imbalances in /proc/schedstat
>        sched: Move sched domain name out of CONFIG_SCHED_DEBUG
>        docs: Update Schedstat version to 17
> 
> Tianchen Ding (1):
>        sched: Fix race between yield_to() and try_to_wake_up()
> 
> Valentin Schneider (1):
>        sched/fair: Remove CONFIG_CFS_BANDWIDTH=n definition of cfs_bandwidth_used()
> 
> Vincent Guittot (10):
>        sched/fair: Rename h_nr_running into h_nr_queued
>        sched/fair: Add new cfs_rq.h_nr_runnable
>        sched/fair: Use the new cfs_rq.h_nr_runnable
>        sched/fair: Removed unsued cfs_rq.h_nr_delayed
>        sched/fair: Rename cfs_rq.idle_h_nr_running into h_nr_idle
>        sched/fair: Remove unused cfs_rq.idle_nr_running
>        sched/fair: Rename cfs_rq.nr_running into nr_queued
>        sched/fair: Do not try to migrate delayed dequeue task
>        sched/fair: Fix variable declaration position
>        sched/fair: Encapsulate set custom slice in a __setparam_fair() function
> 
> Vishal Chourasia (1):
>        sched/fair: Fix CPU bandwidth limit bypass during CPU hotplug
> 
> Waiman Long (4):
>        sched/core: Remove HK_TYPE_SCHED
>        sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
>        sched/isolation: Consolidate housekeeping cpumasks that are always identical
>        sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE
> 
> Wander Lairson Costa (1):
>        sched/deadline: Consolidate Timer Cancellation
> 
> Yafang Shao (3):
>        sched: Define sched_clock_irqtime as static key
>        sched: Don't account irq time if sched_clock_irqtime is disabled
>        sched, psi: Don't account irq time if sched_clock_irqtime is disabled
> 
> 
>   Documentation/admin-guide/kernel-parameters.txt |   4 +-
>   Documentation/scheduler/sched-stats.rst         | 126 ++++---
>   arch/x86/include/asm/topology.h                 |   4 +-
>   arch/x86/kernel/itmt.c                          |  81 ++---
>   arch/x86/kernel/smpboot.c                       |  19 +-
>   include/linux/sched.h                           |  10 +
>   include/linux/sched/isolation.h                 |  21 +-
>   include/linux/sched/topology.h                  |  13 +-
>   kernel/rseq.c                                   |  98 ++++++
>   kernel/sched/core.c                             |  94 +++--
>   kernel/sched/cputime.c                          |  16 +-
>   kernel/sched/deadline.c                         | 119 +++++--
>   kernel/sched/debug.c                            |  25 +-
>   kernel/sched/fair.c                             | 444 ++++++++++++++----------
>   kernel/sched/features.h                         |   9 +
>   kernel/sched/isolation.c                        |  22 +-
>   kernel/sched/pelt.c                             |   4 +-
>   kernel/sched/psi.c                              |   7 +-
>   kernel/sched/sched.h                            |  37 +-
>   kernel/sched/stats.c                            |  11 +-
>   kernel/sched/stats.h                            |   4 +
>   kernel/sched/syscalls.c                         |  18 +-
>   kernel/sched/topology.c                         |  12 +-
>   23 files changed, 720 insertions(+), 478 deletions(-)

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

Re: [GIT PULL v2] Scheduler enhancements for v6.14

[Mathieu Desnoyers]

On 2025-01-21 06:49, Mathieu Desnoyers wrote:
> On 2025-01-21 02:23, Ingo Molnar wrote:
>>
>> * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
>>
>>> On 20-Jan-2025 12:07:41 PM, Ingo Molnar wrote:
>>>>
>>>> Linus,
>>>>
>>>> Please pull the latest sched/core Git tree from:
>>>>
>>>>     git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 
>>>> sched-core-2025-01-20
>>>>
>>>>     # HEAD: 7d9da040575b343085287686fa902a5b2d43c7ca psi: Fix race 
>>>> when task wakes up before psi_sched_switch() adjusts flags
>>>>
>>>> Scheduler enhancements for v6.14:
>>>
>>> [...]
>>>
>>>>   - RSEQ enhancements:
>>>>
>>>>     - Validate read-only fields under DEBUG_RSEQ config
>>>>       (Mathieu Desnoyers)
>>>
>>> FYI, a regression introduced by this commit was reported by s390x
>>> glibc developers testing against linux-next:
>>>
>>> https://sourceware.org/pipermail/libc-alpha/2025-January/163993.html
>>>
>>> I've sent a fix here:
>>>
>>> https://lore.kernel.org/lkml/20250116205956.836074-1-mathieu.desnoyers@efficios.com/
>>>
>>> The commit introducing the issue is in this PR, but not the fix.
>>
>> Indeed - with the bug RSEQ_FLAG_UNREGISTER would fail with an incorrect
>> -EFAULT return.
>>
>> I've applied your fix, and updated the pull request for Linus further
>> below. If Linus has already pulled I'll send a fixes pull request
>> separately, or Linus can apply the fix from email directly:
>>
>>    Acked-by: Ingo Molnar <mingo@kernel.org>
>>
>> Or he can pull the sched-core-2025-01-21 tag below safely on top of
>> sched-core-2025-01-20, which will result in a diffstat of:
>>
>>    Mathieu Desnoyers (1):
>>        rseq: Fix rseq unregistration regression
>>
>>    kernel/rseq.c | 2 +-
>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> Since I booted the scheduler tree on generic desktops and it was tested
>> on other systems as well and nothing appeared to be broken, I presume
>> RSEQ_FLAG_UNREGISTER is used only in libc syscall-testcases and in
>> specific applications?
> 
> Nowadays, rseq unregistration is used by specialized applications (e.g.
> tcmalloc) which disable glibc rseq support with the glibc tunable
> and register it themselves. (GLIBC_TUNABLES=glibc.pthread.rseq=0)
> 
> A recent glibc (2.35+) don't use explicit rseq unregistration, it's
> unregistered implicitly when the thread exits.
> 
> I'll make a note to add a test case for GLIBC_TUNABLES=glibc.pthread.rseq=0
> in the rseq selftests and librseq to improve test coverage when using a
> recent glibc.
> 
> We have all the code in there to use rseq unregistration, but it is skipped
> when glibc 2.35+ is handling the registration.

It turns out that it is covered by both librseq and glibc tests, just
not by the kernel rseq selftests:

librseq test: tests/syscall_errors_test.c
glibc test: sysdeps/unix/sysv/linux/tst-rseq-disable.c

We should import the librseq test into the kernel rseq selftests as
well. CCing Michael Jeanson who will take care of this.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

Re: [GIT PULL] Scheduler enhancements for v6.14

[pr-tracker-bot]

The pull request you sent on Mon, 20 Jan 2025 12:07:41 +0100:

> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-20

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/40724ecafccb1fb62b66264854e8c3ad394c8f3d

Thank you!

-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/prtracker.html

Re: [GIT PULL v2] Scheduler enhancements for v6.14

[pr-tracker-bot]

The pull request you sent on Tue, 21 Jan 2025 08:23:03 +0100:

> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2025-01-21

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/62de6e1685269e1637a6c6684c8be58cc8d4ff38

Thank you!

-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/prtracker.html

Re: [GIT PULL v2] Scheduler enhancements for v6.14

[Ingo Molnar]

* Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> > > Since I booted the scheduler tree on generic desktops and it was 
> > > tested on other systems as well and nothing appeared to be 
> > > broken, I presume RSEQ_FLAG_UNREGISTER is used only in libc 
> > > syscall-testcases and in specific applications?
> > 
> > Nowadays, rseq unregistration is used by specialized applications 
> > (e.g. tcmalloc) which disable glibc rseq support with the glibc 
> > tunable and register it themselves. 
> > (GLIBC_TUNABLES=glibc.pthread.rseq=0)
> > 
> > A recent glibc (2.35+) don't use explicit rseq unregistration, it's 
> > unregistered implicitly when the thread exits.
> > 
> > I'll make a note to add a test case for 
> > GLIBC_TUNABLES=glibc.pthread.rseq=0 in the rseq selftests and 
> > librseq to improve test coverage when using a recent glibc.
> > 
> > We have all the code in there to use rseq unregistration, but it is 
> > skipped when glibc 2.35+ is handling the registration.
> 
> It turns out that it is covered by both librseq and glibc tests, just 
> not by the kernel rseq selftests:
> 
> librseq test: tests/syscall_errors_test.c
> glibc test: sysdeps/unix/sysv/linux/tst-rseq-disable.c
> 
> We should import the librseq test into the kernel rseq selftests as
> well. CCing Michael Jeanson who will take care of this.

Thank you! Linus just pulled the v2 pull request, so all should be good 
upstream.

	Ingo