[GIT PULL] scheduler changes for v5.14

[GIT PULL] scheduler changes for v5.14

[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-2021-06-28

   # HEAD: adf3c31e18b765ea24eba7b0c1efc076b8ee3d55 sched/doc: Update the CPU capacity asymmetry bits

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>
 Thanks,

	Ingo

------------------>
Alexey Dobriyan (4):
      sched: Make nr_running() return 32-bit value
      sched: Make nr_iowait() return 32-bit value
      sched: Make nr_iowait_cpu() return 32-bit value
      sched: Make multiple runqueue task counters 32-bit

Aubrey Li (1):
      sched: Migration changes for core scheduling

Beata Michalska (3):
      sched/core: Introduce SD_ASYM_CPUCAPACITY_FULL sched_domain flag
      sched/topology: Rework CPU capacity asymmetry detection
      sched/doc: Update the CPU capacity asymmetry bits

Chris Hyser (2):
      sched: prctl() core-scheduling interface
      kselftest: Add test for core sched prctl interface

Dietmar Eggemann (1):
      sched/fair: Return early from update_tg_cfs_load() if delta == 0

Eric Dumazet (1):
      sched/debug: Remove obsolete init_schedstats()

Frederic Weisbecker (1):
      sched: Stop PF_NO_SETAFFINITY from being inherited by various init system threads

Huaixin Chang (1):
      sched/fair: Introduce the burstable CFS controller

Ingo Molnar (1):
      sched: Fix leftover comment typos

Joel Fernandes (Google) (3):
      sched: Fix priority inversion of cookied task with sibling
      sched/fair: Snapshot the min_vruntime of CPUs on force idle
      Documentation: Add usecases, design and interface for core scheduling

Lukasz Luba (3):
      thermal/cpufreq_cooling: Update offline CPUs per-cpu thermal_pressure
      sched/fair: Take thermal pressure into account while estimating energy
      sched/cpufreq: Consider reduced CPU capacity in energy calculation

Masahiro Yamada (1):
      sched: Fix a stale comment in pick_next_task()

Mel Gorman (1):
      delayacct: Document task_delayacct sysctl

Odin Ugedal (1):
      sched/fair: Fix ascii art by relpacing tabs

Oleg Nesterov (1):
      sched/core: Remove the pointless BUG_ON(!task) from wake_up_q()

Paul Gortmaker (1):
      sched/isolation: Reconcile rcu_nocbs= and nohz_full=

Peter Zijlstra (31):
      delayacct: Use sched_clock()
      sched: Rename sched_info_{queued,dequeued}
      sched: Simplify sched_info_on()
      kvm: Select SCHED_INFO instead of TASK_DELAY_ACCT
      delayacct: Add static_branch in scheduler hooks
      delayacct: Default disabled
      delayacct: Add sysctl to enable at runtime
      sched/fair: Add a few assertions
      sched: Provide raw_spin_rq_*lock*() helpers
      sched: Wrap rq::lock access
      sched: Prepare for Core-wide rq->lock
      sched: Core-wide rq->lock
      sched: Optimize rq_lockp() usage
      sched: Allow sched_core_put() from atomic context
      sched: Introduce sched_class::pick_task()
      sched: Basic tracking of matching tasks
      sched: Add core wide task selection and scheduling
      sched: Trivial forced-newidle balancer
      sched: Trivial core scheduling cookie management
      sched: Inherit task cookie on fork()
      sched,stats: Further simplify sched_info
      sched: Add CONFIG_SCHED_CORE help text
      sched,init: Fix DEBUG_PREEMPT vs early boot
      sched/fair: Age the average idle time
      sched: Unbreak wakeups
      sched: Introduce task_is_running()
      sched,perf,kvm: Fix preemption condition
      sched: Add get_current_state()
      sched,timer: Use __set_current_state()
      sched,arch: Remove unused TASK_STATE offsets
      sched: Change task_struct::state

Pierre Gondois (2):
      sched/fair: Only compute base_energy_pd if necessary
      sched/fair: Fix negative energy delta in find_energy_efficient_cpu()

Qais Yousef (3):
      sched/uclamp: Fix wrong implementation of cpu.uclamp.min
      sched/uclamp: Fix locking around cpu_util_update_eff()
      sched/uclamp: Fix uclamp_tg_restrict()

Rik van Riel (1):
      sched,fair: Skip newidle_balance if a wakeup is pending

Valentin Schneider (3):
      sched/core: Initialize the idle task with preemption disabled
      sched: Make the idle task quack like a per-CPU kthread
      sched: Don't defer CPU pick to migration_cpu_stop()

Vincent Donnefort (2):
      sched/rt: Fix RT utilization tracking during policy change
      sched/rt: Fix Deadline utilization tracking during policy change

Vincent Guittot (1):
      sched/pelt: Check that *_avg are null when *_sum are

Vineeth Pillai (1):
      sched/fair: Fix forced idle sibling starvation corner case

Yejune Deng (1):
      lib/smp_processor_id: Use is_percpu_thread() instead of nr_cpus_allowed

Zhaoyang Huang (1):
      psi: Fix race between psi_trigger_create/destroy


 Documentation/accounting/delay-accounting.rst      |   12 +-
 .../admin-guide/hw-vuln/core-scheduling.rst        |  223 ++++
 Documentation/admin-guide/hw-vuln/index.rst        |    1 +
 Documentation/admin-guide/kernel-parameters.txt    |    2 +-
 Documentation/admin-guide/sysctl/kernel.rst        |    7 +
 Documentation/scheduler/sched-capacity.rst         |    6 +-
 Documentation/scheduler/sched-energy.rst           |    2 +-
 arch/alpha/kernel/process.c                        |    2 +-
 arch/alpha/kernel/smp.c                            |    1 -
 arch/arc/kernel/smp.c                              |    1 -
 arch/arc/kernel/stacktrace.c                       |    2 +-
 arch/arm/kernel/process.c                          |    2 +-
 arch/arm/kernel/smp.c                              |    1 -
 arch/arm64/include/asm/preempt.h                   |    2 +-
 arch/arm64/kernel/process.c                        |    2 +-
 arch/arm64/kernel/smp.c                            |    1 -
 arch/arm64/kvm/Kconfig                             |    5 +-
 arch/csky/kernel/asm-offsets.c                     |    1 -
 arch/csky/kernel/smp.c                             |    1 -
 arch/csky/kernel/stacktrace.c                      |    2 +-
 arch/h8300/kernel/asm-offsets.c                    |    1 -
 arch/h8300/kernel/process.c                        |    2 +-
 arch/hexagon/kernel/process.c                      |    2 +-
 arch/ia64/kernel/mca.c                             |    2 +-
 arch/ia64/kernel/process.c                         |    4 +-
 arch/ia64/kernel/ptrace.c                          |    8 +-
 arch/ia64/kernel/smpboot.c                         |    1 -
 arch/m68k/kernel/process.c                         |    2 +-
 arch/microblaze/kernel/asm-offsets.c               |    1 -
 arch/mips/kernel/asm-offsets.c                     |    1 -
 arch/mips/kernel/process.c                         |    2 +-
 arch/mips/kernel/smp.c                             |    1 -
 arch/nds32/kernel/process.c                        |    2 +-
 arch/nios2/kernel/process.c                        |    2 +-
 arch/openrisc/kernel/asm-offsets.c                 |    1 -
 arch/openrisc/kernel/smp.c                         |    2 -
 arch/parisc/kernel/asm-offsets.c                   |    1 -
 arch/parisc/kernel/process.c                       |    4 +-
 arch/parisc/kernel/smp.c                           |    1 -
 arch/powerpc/kernel/process.c                      |    4 +-
 arch/powerpc/kernel/smp.c                          |    1 -
 arch/powerpc/xmon/xmon.c                           |   13 +-
 arch/riscv/kernel/smpboot.c                        |    1 -
 arch/riscv/kernel/stacktrace.c                     |    2 +-
 arch/s390/include/asm/preempt.h                    |    4 +-
 arch/s390/kernel/process.c                         |    2 +-
 arch/s390/kernel/smp.c                             |    1 -
 arch/s390/mm/fault.c                               |    2 +-
 arch/sh/kernel/process_32.c                        |    2 +-
 arch/sh/kernel/smp.c                               |    2 -
 arch/sparc/kernel/process_32.c                     |    3 +-
 arch/sparc/kernel/process_64.c                     |    3 +-
 arch/sparc/kernel/smp_32.c                         |    1 -
 arch/sparc/kernel/smp_64.c                         |    3 -
 arch/um/kernel/process.c                           |    2 +-
 arch/x86/include/asm/preempt.h                     |    2 +-
 arch/x86/kernel/process.c                          |    4 +-
 arch/x86/kernel/smpboot.c                          |    1 -
 arch/x86/kvm/Kconfig                               |    5 +-
 arch/xtensa/kernel/process.c                       |    2 +-
 arch/xtensa/kernel/smp.c                           |    1 -
 block/blk-mq.c                                     |    6 +-
 drivers/cpuidle/governors/menu.c                   |    6 +-
 drivers/md/dm.c                                    |    6 +-
 drivers/net/ethernet/qualcomm/qca_spi.c            |    6 +-
 drivers/thermal/cpufreq_cooling.c                  |    2 +-
 drivers/usb/gadget/udc/max3420_udc.c               |   15 +-
 drivers/usb/host/max3421-hcd.c                     |    3 +-
 fs/binfmt_elf.c                                    |    8 +-
 fs/binfmt_elf_fdpic.c                              |    4 +-
 fs/proc/loadavg.c                                  |    2 +-
 fs/proc/stat.c                                     |    4 +-
 fs/userfaultfd.c                                   |    4 +-
 include/asm-generic/preempt.h                      |    2 +-
 include/linux/delayacct.h                          |   22 +-
 include/linux/energy_model.h                       |   16 +-
 include/linux/kthread.h                            |    2 +
 include/linux/sched.h                              |   50 +-
 include/linux/sched/cpufreq.h                      |    2 +-
 include/linux/sched/debug.h                        |    2 +-
 include/linux/sched/sd_flags.h                     |   10 +
 include/linux/sched/signal.h                       |    2 +-
 include/linux/sched/stat.h                         |   16 +-
 include/linux/sched_clock.h                        |    2 +-
 include/uapi/linux/prctl.h                         |    8 +
 init/init_task.c                                   |    2 +-
 init/main.c                                        |   17 +-
 kernel/Kconfig.preempt                             |   20 +
 kernel/cgroup/cgroup-v1.c                          |    2 +-
 kernel/debug/kdb/kdb_support.c                     |   18 +-
 kernel/delayacct.c                                 |   71 +-
 kernel/events/core.c                               |    7 +-
 kernel/fork.c                                      |   12 +-
 kernel/freezer.c                                   |    2 +-
 kernel/hung_task.c                                 |    2 +-
 kernel/kcsan/report.c                              |    2 +-
 kernel/kthread.c                                   |   34 +-
 kernel/locking/lockdep.c                           |    2 +-
 kernel/locking/mutex.c                             |    6 +-
 kernel/locking/rtmutex.c                           |    4 +-
 kernel/locking/rwsem.c                             |    2 +-
 kernel/ptrace.c                                    |   12 +-
 kernel/rcu/rcutorture.c                            |    4 +-
 kernel/rcu/tree_plugin.h                           |    2 +-
 kernel/rcu/tree_stall.h                            |   12 +-
 kernel/sched/Makefile                              |    1 +
 kernel/sched/core.c                                | 1138 +++++++++++++++++---
 kernel/sched/core_sched.c                          |  229 ++++
 kernel/sched/cpuacct.c                             |   12 +-
 kernel/sched/cpufreq_schedutil.c                   |    1 +
 kernel/sched/deadline.c                            |   50 +-
 kernel/sched/debug.c                               |    4 +-
 kernel/sched/fair.c                                |  440 +++++---
 kernel/sched/idle.c                                |   13 +-
 kernel/sched/isolation.c                           |    4 +-
 kernel/sched/loadavg.c                             |    2 +-
 kernel/sched/pelt.h                                |    2 +-
 kernel/sched/psi.c                                 |   12 +-
 kernel/sched/rt.c                                  |   48 +-
 kernel/sched/sched.h                               |  437 ++++++--
 kernel/sched/stats.h                               |   68 +-
 kernel/sched/stop_task.c                           |   14 +-
 kernel/sched/topology.c                            |  213 ++--
 kernel/signal.c                                    |    2 +-
 kernel/smpboot.c                                   |    1 -
 kernel/softirq.c                                   |    5 +-
 kernel/sys.c                                       |    5 +
 kernel/sysctl.c                                    |   12 +
 kernel/time/timer.c                                |    2 +-
 lib/smp_processor_id.c                             |    6 +-
 lib/syscall.c                                      |    4 +-
 mm/compaction.c                                    |    2 +-
 net/core/dev.c                                     |    2 +-
 tools/include/uapi/linux/prctl.h                   |    8 +
 tools/testing/selftests/sched/.gitignore           |    1 +
 tools/testing/selftests/sched/Makefile             |   14 +
 tools/testing/selftests/sched/config               |    1 +
 tools/testing/selftests/sched/cs_prctl_test.c      |  338 ++++++
 virt/kvm/kvm_main.c                                |    2 +-
 139 files changed, 3122 insertions(+), 781 deletions(-)
 create mode 100644 Documentation/admin-guide/hw-vuln/core-scheduling.rst
 create mode 100644 kernel/sched/core_sched.c
 create mode 100644 tools/testing/selftests/sched/.gitignore
 create mode 100644 tools/testing/selftests/sched/Makefile
 create mode 100644 tools/testing/selftests/sched/config
 create mode 100644 tools/testing/selftests/sched/cs_prctl_test.c

Re: [GIT PULL] scheduler changes for v5.14

[Linus Torvalds]

On Sun, Jun 27, 2021 at 11:51 PM Ingo Molnar <mingo@kernel.org> wrote:
>
>     - Add "Core Scheduling" via CONFIG_SCHED_CORE=y,

Grr.

Why is this feature "default y"? I see no reason why anybody would
enable it outside of cloud providers, which doesn't argue for it being
on by default.

               Linus

[PATCH] sched/core: Disable CONFIG_SCHED_CORE by default

[Ingo Molnar]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Sun, Jun 27, 2021 at 11:51 PM Ingo Molnar <mingo@kernel.org> wrote:
> >
> >     - Add "Core Scheduling" via CONFIG_SCHED_CORE=y,
> 
> Grr.
> 
> Why is this feature "default y"? I see no reason why anybody would
> enable it outside of cloud providers, which doesn't argue for it being
> on by default.

You are completely right, I missed this. Find below the patch to fix it - 
feel free to apply it directly, will rebase sched/urgent accordingly.

Thanks,

	Ingo

=====================>
From: Ingo Molnar <mingo@kernel.org>
Date: Mon, 28 Jun 2021 21:55:16 +0200
Subject: [PATCH] sched/core: Disable CONFIG_SCHED_CORE by default

This option adds extra overhead to the scheduler, and most users wouldn't want it.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/Kconfig.preempt | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index bd7c4147b9a8..3654a92e7e70 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -102,7 +102,6 @@ config PREEMPT_DYNAMIC
 
 config SCHED_CORE
 	bool "Core Scheduling for SMT"
-	default y
 	depends on SCHED_SMT
 	help
 	  This option permits Core Scheduling, a means of coordinated task

Re: [PATCH] sched/core: Disable CONFIG_SCHED_CORE by default

[Linus Torvalds]

On Mon, Jun 28, 2021 at 12:57 PM Ingo Molnar <mingo@kernel.org> wrote:
>
> You are completely right, I missed this. Find below the patch to fix it -

I think you should update the helptext too, which currently says that
it's enabled if SCHED_SMT is enabled.

And yes, it may be that there is no measurable performance downside,
but this feature has been discussed and under development for a long
time now, and I'd like the default to try to limit the impact since it
makes little sense to most people.

          Linus

[PATCH, -v2] sched/core: Disable CONFIG_SCHED_CORE by default

[Ingo Molnar]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Jun 28, 2021 at 12:57 PM Ingo Molnar <mingo@kernel.org> wrote:
> >
> > You are completely right, I missed this. Find below the patch to fix it -
> 
> I think you should update the helptext too, which currently says that
> it's enabled if SCHED_SMT is enabled.
> 
> And yes, it may be that there is no measurable performance downside,
> but this feature has been discussed and under development for a long
> time now, and I'd like the default to try to limit the impact since it
> makes little sense to most people.

Updated patch attached, which updates the help text and clarifies what 
overhead there is.

While the worst of the overhead is behind the __sched_core_enabled static 
key, there's a notable increase in pick_next_task(), which might be 
measurable with the right microbenchmark.

So the 'no overhead' claim is probably not entirely true, and comes from 
the context of *horrible* overhead of early iterations of the core 
scheduling feature ...

Thanks,

	Ingo

===================================>
From: Ingo Molnar <mingo@kernel.org>
Date: Mon, 28 Jun 2021 21:55:16 +0200
Subject: [PATCH] sched/core: Disable CONFIG_SCHED_CORE by default

This option at minimum adds extra code to the scheduler - even if
it's default unused - and most users wouldn't want it.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/Kconfig.preempt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index bd7c4147b9a8..5876e30c5740 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -102,7 +102,6 @@ config PREEMPT_DYNAMIC
 
 config SCHED_CORE
 	bool "Core Scheduling for SMT"
-	default y
 	depends on SCHED_SMT
 	help
 	  This option permits Core Scheduling, a means of coordinated task
@@ -115,7 +114,8 @@ config SCHED_CORE
 	   - mitigation of some (not all) SMT side channels;
 	   - limiting SMT interference to improve determinism and/or performance.
 
-	  SCHED_CORE is default enabled when SCHED_SMT is enabled -- when
-	  unused there should be no impact on performance.
+	  SCHED_CORE is default disabled. When it is enabled and unused,
+	  which is the likely usage by Linux distributions, there should
+	  be no measurable impact on performance.
 
 

Re: [GIT PULL] scheduler changes for v5.14

[pr-tracker-bot]

The pull request you sent on Mon, 28 Jun 2021 08:51:28 +0200:

> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-core-2021-06-28

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/54a728dc5e4feb0a9278ad62b19f34ad21ed0ee4

Thank you!

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

[GIT PULL] scheduler fixes for v5.14

[Ingo Molnar]

Linus,

Please pull the latest sched/urgent git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-2021-06-30

   # HEAD: a22a5cb81e20657194fde6c835e07d28c4dfddbe Merge branch 'sched/core' into sched/urgent, to pick up fix

- 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.

 Thanks,

	Ingo

------------------>
Ingo Molnar (1):
      sched/core: Disable CONFIG_SCHED_CORE by default

Odin Ugedal (1):
      sched/fair: Ensure _sum and _avg values stay consistent


 kernel/Kconfig.preempt | 6 +++---
 kernel/sched/fair.c    | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index bd7c4147b9a8..5876e30c5740 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -102,7 +102,6 @@ config PREEMPT_DYNAMIC
 
 config SCHED_CORE
 	bool "Core Scheduling for SMT"
-	default y
 	depends on SCHED_SMT
 	help
 	  This option permits Core Scheduling, a means of coordinated task
@@ -115,7 +114,8 @@ config SCHED_CORE
 	   - mitigation of some (not all) SMT side channels;
 	   - limiting SMT interference to improve determinism and/or performance.
 
-	  SCHED_CORE is default enabled when SCHED_SMT is enabled -- when
-	  unused there should be no impact on performance.
+	  SCHED_CORE is default disabled. When it is enabled and unused,
+	  which is the likely usage by Linux distributions, there should
+	  be no measurable impact on performance.
 
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4a3e61a88acc..45edf61eed73 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3657,15 +3657,15 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
 
 		r = removed_load;
 		sub_positive(&sa->load_avg, r);
-		sub_positive(&sa->load_sum, r * divider);
+		sa->load_sum = sa->load_avg * divider;
 
 		r = removed_util;
 		sub_positive(&sa->util_avg, r);
-		sub_positive(&sa->util_sum, r * divider);
+		sa->util_sum = sa->util_avg * divider;
 
 		r = removed_runnable;
 		sub_positive(&sa->runnable_avg, r);
-		sub_positive(&sa->runnable_sum, r * divider);
+		sa->runnable_sum = sa->runnable_avg * divider;
 
 		/*
 		 * removed_runnable is the unweighted version of removed_load so we

Re: [GIT PULL] scheduler fixes for v5.14

[pr-tracker-bot]

The pull request you sent on Wed, 30 Jun 2021 12:53:09 +0200:

> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-2021-06-30

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/a6eaf3850cb171c328a8b0db6d3c79286a1eba9d

Thank you!

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