linux.git/kernel/sched/Makefile, branch v6.6.132

sched/headers: Introduce kernel/sched/build_policy.c and build multiple .c files there

2022-02-23T09:58:33+00:00

Similarly to kernel/sched/build_utility.c, collect all 'scheduling policy' related
source code files into kernel/sched/build_policy.c:

    kernel/sched/idle.c

    kernel/sched/rt.c

    kernel/sched/cpudeadline.c
    kernel/sched/pelt.c

    kernel/sched/cputime.c
    kernel/sched/deadline.c

With the exception of fair.c, which we continue to build as a separate file
for build efficiency and parallelism reasons.

Signed-off-by: Ingo Molnar 
Reviewed-by: Peter Zijlstra

sched/headers: Introduce kernel/sched/build_utility.c and build multiple .c files there

2022-02-23T09:58:33+00:00

Collect all utility functionality source code files into a single kernel/sched/build_utility.c file,
via #include-ing the .c files:

    kernel/sched/clock.c
    kernel/sched/completion.c
    kernel/sched/loadavg.c
    kernel/sched/swait.c
    kernel/sched/wait_bit.c
    kernel/sched/wait.c

CONFIG_CPU_FREQ:
    kernel/sched/cpufreq.c

CONFIG_CPU_FREQ_GOV_SCHEDUTIL:
    kernel/sched/cpufreq_schedutil.c

CONFIG_CGROUP_CPUACCT:
    kernel/sched/cpuacct.c

CONFIG_SCHED_DEBUG:
    kernel/sched/debug.c

CONFIG_SCHEDSTATS:
    kernel/sched/stats.c

CONFIG_SMP:
   kernel/sched/cpupri.c
   kernel/sched/stop_task.c
   kernel/sched/topology.c

CONFIG_SCHED_CORE:
   kernel/sched/core_sched.c

CONFIG_PSI:
   kernel/sched/psi.c

CONFIG_MEMBARRIER:
   kernel/sched/membarrier.c

CONFIG_CPU_ISOLATION:
   kernel/sched/isolation.c

CONFIG_SCHED_AUTOGROUP:
   kernel/sched/autogroup.c

The goal is to amortize the 60+ KLOC header bloat from over a dozen build units into
a single build unit.

The build time of build_utility.c also roughly matches the build time of core.c and
fair.c - allowing better load-balancing of scheduler-only rebuilds.

Signed-off-by: Ingo Molnar 
Reviewed-by: Peter Zijlstra

sched/headers: sched/clock: Mark all functions 'notrace', remove CC_FLAGS_FTRACE build asymmetry

2022-02-23T07:22:04+00:00

Mark all non-init functions in kernel/sched.c as 'notrace', instead of
turning them all off via CC_FLAGS_FTRACE.

This is going to allow the treatment of this file as any other scheduler
file, and it can be #include-ed in compound compilation units as well.

Signed-off-by: Ingo Molnar 
Reviewed-by: Peter Zijlstra

sched, kcsan: Enable memory barrier instrumentation

2021-12-10T00:42:28+00:00

There's no fundamental reason to disable KCSAN for scheduler code,
except for excessive noise and performance concerns (instrumenting
scheduler code is usually a good way to stress test KCSAN itself).

However, several core sched functions imply memory barriers that are
invisible to KCSAN without instrumentation, but are required to avoid
false positives. Therefore, unconditionally enable instrumentation of
memory barriers in scheduler code. Also update the comment to reflect
this and be a bit more brief.

Signed-off-by: Marco Elver 
Signed-off-by: Paul E. McKenney

sched: Disable -Wunused-but-set-variable

2021-10-15T09:25:15+00:00

The compilers can't deal with obvious DCE vs that warning, resulting
in code like:

	if (0) {
		sched sched_statistics *stats;

		stats = __schedstats_from_se(se);

		...
	}

triggering the warning. Kill the warning to make the robots stop
reporting this.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Nathan Chancellor 
Link: https://lkml.kernel.org/r/YWWPLnaZGybHsTkv@hirez.programming.kicks-ass.net

sched: Trivial core scheduling cookie management

2021-05-12T09:43:31+00:00

In order to not have to use pid_struct, create a new, smaller,
structure to manage task cookies for core scheduling.

Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Don Hiatt 
Tested-by: Hongyu Ning 
Tested-by: Vincent Guittot 
Link: https://lkml.kernel.org/r/20210422123308.919768100@infradead.org

kcsan: Improve various small stylistic details

2019-11-20T09:47:23+00:00

Tidy up a few bits:

  - Fix typos and grammar, improve wording.

  - Remove spurious newlines that are col80 warning artifacts where the
    resulting line-break is worse than the disease it's curing.

  - Use core kernel coding style to improve readability and reduce
    spurious code pattern variations.

  - Use better vertical alignment for structure definitions and initialization
    sequences.

  - Misc other small details.

No change in functionality intended.

Cc: linux-kernel@vger.kernel.org
Cc: Marco Elver 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Thomas Gleixner 
Cc: Paul E. McKenney 
Cc: Will Deacon 
Signed-off-by: Ingo Molnar

build, kcsan: Add KCSAN build exceptions

2019-11-16T15:23:14+00:00

This blacklists several compilation units from KCSAN. See the respective
inline comments for the reasoning.

Signed-off-by: Marco Elver 
Acked-by: Paul E. McKenney 
Signed-off-by: Paul E. McKenney

psi: pressure stall information for CPU, memory, and IO

2018-10-26T23:26:32+00:00

When systems are overcommitted and resources become contended, it's hard
to tell exactly the impact this has on workload productivity, or how close
the system is to lockups and OOM kills.  In particular, when machines work
multiple jobs concurrently, the impact of overcommit in terms of latency
and throughput on the individual job can be enormous.

In order to maximize hardware utilization without sacrificing individual
job health or risk complete machine lockups, this patch implements a way
to quantify resource pressure in the system.

A kernel built with CONFIG_PSI=y creates files in /proc/pressure/ that
expose the percentage of time the system is stalled on CPU, memory, or IO,
respectively.  Stall states are aggregate versions of the per-task delay
accounting delays:

       cpu: some tasks are runnable but not executing on a CPU
       memory: tasks are reclaiming, or waiting for swapin or thrashing cache
       io: tasks are waiting for io completions

These percentages of walltime can be thought of as pressure percentages,
and they give a general sense of system health and productivity loss
incurred by resource overcommit.  They can also indicate when the system
is approaching lockup scenarios and OOMs.

To do this, psi keeps track of the task states associated with each CPU
and samples the time they spend in stall states.  Every 2 seconds, the
samples are averaged across CPUs - weighted by the CPUs' non-idle time to
eliminate artifacts from unused CPUs - and translated into percentages of
walltime.  A running average of those percentages is maintained over 10s,
1m, and 5m periods (similar to the loadaverage).

[hannes@cmpxchg.org: doc fixlet, per Randy]
  Link: http://lkml.kernel.org/r/20180828205625.GA14030@cmpxchg.org
[hannes@cmpxchg.org: code optimization]
  Link: http://lkml.kernel.org/r/20180907175015.GA8479@cmpxchg.org
[hannes@cmpxchg.org: rename psi_clock() to psi_update_work(), per Peter]
  Link: http://lkml.kernel.org/r/20180907145404.GB11088@cmpxchg.org
[hannes@cmpxchg.org: fix build]
  Link: http://lkml.kernel.org/r/20180913014222.GA2370@cmpxchg.org
Link: http://lkml.kernel.org/r/20180828172258.3185-9-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner 
Acked-by: Peter Zijlstra (Intel) 
Tested-by: Daniel Drake 
Tested-by: Suren Baghdasaryan 
Cc: Christopher Lameter 
Cc: Ingo Molnar 
Cc: Johannes Weiner 
Cc: Mike Galbraith 
Cc: Peter Enderborg 
Cc: Randy Dunlap 
Cc: Shakeel Butt 
Cc: Tejun Heo 
Cc: Vinayak Menon 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched/pelt: Move PELT related code in a dedicated file

2018-07-15T21:51:20+00:00

We want to track rt_rq's utilization as a part of the estimation of the
whole rq's utilization. This is necessary because rt tasks can steal
utilization to cfs tasks and make them lighter than they are.
As we want to use the same load tracking mecanism for both and prevent
useless dependency between cfs and rt code, PELT code is moved in a
dedicated file.

Signed-off-by: Vincent Guittot 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Linus Torvalds 
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: claudio@evidence.eu.com
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: patrick.bellasi@arm.com
Cc: quentin.perret@arm.com
Cc: rjw@rjwysocki.net
Cc: valentin.schneider@arm.com
Cc: viresh.kumar@linaro.org
Link: http://lkml.kernel.org/r/1530200714-4504-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar