linux-stable.git/kernel/sched/cpuacct.c, branch linux-5.17.y

sched/cpuacct: Fix charge percpu cpuusage

2022-04-08T11:57:40+00:00

[ Upstream commit 248cc9993d1cc12b8e9ed716cc3fc09f6c3517dd ]

The cpuacct_account_field() is always called by the current task
itself, so it's ok to use __this_cpu_add() to charge the tick time.

But cpuacct_charge() maybe called by update_curr() in load_balance()
on a random CPU, different from the CPU on which the task is running.
So __this_cpu_add() will charge that cputime to a random incorrect CPU.

Fixes: 73e6aafd9ea8 ("sched/cpuacct: Simplify the cpuacct code")
Reported-by: Minye Zhu 
Signed-off-by: Chengming Zhou 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20220220051426.5274-1-zhouchengming@bytedance.com
Signed-off-by: Sasha Levin

sched/cpuacct: Make user/system times in cpuacct.stat more precise

2021-11-23T08:55:22+00:00

cpuacct.stat shows user time based on raw random precision tick
based counters. Use cputime_addjust() to scale these values against the
total runtime accounted by the scheduler, like we already do
for user/system times in /proc//stat.

Signed-off-by: Andrey Ryabinin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Daniel Jordan 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20211115164607.23784-4-arbn@yandex-team.com

sched/cpuacct: Fix user/system in shown cpuacct.usage*

2021-11-23T08:55:22+00:00

cpuacct has 2 different ways of accounting and showing user
and system times.

The first one uses cpuacct_account_field() to account times
and cpuacct.stat file to expose them. And this one seems to work ok.

The second one is uses cpuacct_charge() function for accounting and
set of cpuacct.usage* files to show times. Despite some attempts to
fix it in the past it still doesn't work. Sometimes while running KVM
guest the cpuacct_charge() accounts most of the guest time as
system time. This doesn't match with user&system times shown in
cpuacct.stat or proc//stat.

Demonstration:
 # git clone https://github.com/aryabinin/kvmsample
 # make
 # mkdir /sys/fs/cgroup/cpuacct/test
 # echo $$ > /sys/fs/cgroup/cpuacct/test/tasks
 # ./kvmsample &
 # for i in {1..5}; do cat /sys/fs/cgroup/cpuacct/test/cpuacct.usage_sys; sleep 1; done
 1976535645
 2979839428
 3979832704
 4983603153
 5983604157

Use cpustats accounted in cpuacct_account_field() as the source
of user/sys times for cpuacct.usage* files. Make cpuacct_charge()
to account only summary execution time.

Fixes: d740037fac70 ("sched/cpuacct: Split usage accounting into user_usage and sys_usage")
Signed-off-by: Andrey Ryabinin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Daniel Jordan 
Acked-by: Tejun Heo 
Cc: 
Link: https://lore.kernel.org/r/20211115164607.23784-3-arbn@yandex-team.com

cpuacct: Convert BUG_ON() to WARN_ON_ONCE()

2021-11-23T08:55:22+00:00

Replace fatal BUG_ON() with more safe WARN_ON_ONCE() in cpuacct_cpuusage_read().

Signed-off-by: Andrey Ryabinin 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Daniel Jordan 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20211115164607.23784-2-arbn@yandex-team.com

sched: Wrap rq::lock access

2021-05-12T09:43:26+00:00

In preparation of playing games with rq->lock, abstract the thing
using an accessor.

Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Don Hiatt 
Tested-by: Hongyu Ning 
Tested-by: Vincent Guittot 
Link: https://lkml.kernel.org/r/20210422123308.136465446@infradead.org

sched: Fix various typos

2021-03-21T23:11:52+00:00

Fix ~42 single-word typos in scheduler code comments.

We have accumulated a few fun ones over the years. :-)

Signed-off-by: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Mike Galbraith 
Cc: Juri Lelli 
Cc: Vincent Guittot 
Cc: Dietmar Eggemann 
Cc: Steven Rostedt 
Cc: Ben Segall 
Cc: Mel Gorman 
Cc: linux-kernel@vger.kernel.org

sched/cpuacct: Fix charge cpuacct.usage_sys

2020-05-19T18:34:14+00:00

The user_mode(task_pt_regs(tsk)) always return true for
user thread, and false for kernel thread. So it means that
the cpuacct.usage_sys is the time that kernel thread uses
not the time that thread uses in the kernel mode. We can
try get_irq_regs() first, if it is NULL, then we can fall
back to task_pt_regs().

Signed-off-by: Muchun Song 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200420070453.76815-1-songmuchun@bytedance.com

sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr()

2020-05-19T18:34:13+00:00

The cpuacct_charge() and cpuacct_account_field() are called with
rq->lock held, and this means preemption(and IRQs) are indeed
disabled, so it is safe to use __this_cpu_*() to allow for better
code-generation.

Signed-off-by: Muchun Song 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/20200507031039.32615-1-songmuchun@bytedance.com

sched/headers: Simplify and clean up header usage in the scheduler

2018-03-04T11:39:29+00:00

Do the following cleanups and simplifications:

 - sched/sched.h already includes , so no need to
   include it in sched/core.c again.

 - order the  headers alphabetically

 - add all  headers to kernel/sched/sched.h

 - remove all unnecessary includes from the .c files that
   are already included in kernel/sched/sched.h.

Finally, make all scheduler .c files use a single common header:

  #include "sched.h"

... which now contains a union of the relied upon headers.

This makes the various .c files easier to read and easier to handle.

Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

sched: Clean up and harmonize the coding style of the scheduler code base

2018-03-03T14:50:21+00:00

A good number of small style inconsistencies have accumulated
in the scheduler core, so do a pass over them to harmonize
all these details:

 - fix speling in comments,

 - use curly braces for multi-line statements,

 - remove unnecessary parentheses from integer literals,

 - capitalize consistently,

 - remove stray newlines,

 - add comments where necessary,

 - remove invalid/unnecessary comments,

 - align structure definitions and other data types vertically,

 - add missing newlines for increased readability,

 - fix vertical tabulation where it's misaligned,

 - harmonize preprocessor conditional block labeling
   and vertical alignment,

 - remove line-breaks where they uglify the code,

 - add newline after local variable definitions,

No change in functionality:

  md5:
     1191fa0a890cfa8132156d2959d7e9e2  built-in.o.before.asm
     1191fa0a890cfa8132156d2959d7e9e2  built-in.o.after.asm

Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar