linux-toradex.git/kernel/delayacct.c, branch v5.19-rc1

delayacct: track delays from write-protect copy

2022-06-01T22:55:25+00:00

Delay accounting does not track the delay of write-protect copy.  When
tasks trigger many write-protect copys(include COW and unsharing of
anonymous pages[1]), it may spend a amount of time waiting for them.  To
get the delay of tasks in write-protect copy, could help users to evaluate
the impact of using KSM or fork() or GUP.

Also update tools/accounting/getdelays.c:

    / # ./getdelays -dl -p 231
    print delayacct stats ON
    listen forever
    PID     231

    CPU             count     real total  virtual total    delay total  delay average
                     6247     1859000000     2154070021     1674255063          0.268ms
    IO              count    delay total  delay average
                        0              0              0ms
    SWAP            count    delay total  delay average
                        0              0              0ms
    RECLAIM         count    delay total  delay average
                        0              0              0ms
    THRASHING       count    delay total  delay average
                        0              0              0ms
    COMPACT         count    delay total  delay average
                        3          72758              0ms
    WPCOPY          count    delay total  delay average
                     3635      271567604              0ms

[1] commit 31cc5bc4af70("mm: support GUP-triggered unsharing of anonymous pages")

Link: https://lkml.kernel.org/r/20220409014342.2505532-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang 
Reviewed-by: David Hildenbrand 
Reviewed-by: Jiang Xuexin 
Reviewed-by: Ran Xiaokai 
Reviewed-by: wangyong 
Cc: Jonathan Corbet 
Cc: Balbir Singh 
Cc: Mike Kravetz 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton

kernel/delayacct: move delayacct sysctls to its own file

2022-04-06T20:43:44+00:00

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the delayacct sysctl to its own file,
kernel/delayacct.c.

Signed-off-by: tangmeng 
Signed-off-by: Luis Chamberlain

delayacct: track delays from memory compact

2022-01-20T06:52:55+00:00

Delay accounting does not track the delay of memory compact.  When there
is not enough free memory, tasks can spend a amount of their time
waiting for compact.

To get the impact of tasks in direct memory compact, measure the delay
when allocating memory through memory compact.

Also update tools/accounting/getdelays.c:

    / # ./getdelays_next  -di -p 304
    print delayacct stats ON
    printing IO accounting
    PID     304

    CPU             count     real total  virtual total    delay total  delay average
                      277      780000000      849039485       18877296          0.068ms
    IO              count    delay total  delay average
                        0              0              0ms
    SWAP            count    delay total  delay average
                        0              0              0ms
    RECLAIM         count    delay total  delay average
                        5    11088812685           2217ms
    THRASHING       count    delay total  delay average
                        0              0              0ms
    COMPACT         count    delay total  delay average
                        3          72758              0ms
    watch: read=0, write=0, cancelled_write=0

Link: https://lkml.kernel.org/r/1638619795-71451-1-git-send-email-wang.yong12@zte.com.cn
Signed-off-by: wangyong 
Reviewed-by: Jiang Xuexin 
Reviewed-by: Zhang Wenya 
Reviewed-by: Yang Yang 
Reviewed-by: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

delayacct: support swapin delay accounting for swapping without blkio

2022-01-20T06:52:55+00:00

Currently delayacct accounts swapin delay only for swapping that cause
blkio.  If we use zram for swapping, tools/accounting/getdelays can't
get any SWAP delay.

It's useful to get zram swapin delay information, for example to adjust
compress algorithm or /proc/sys/vm/swappiness.

Reference to PSI, it accounts any kind of swapping by doing its work in
swap_readpage(), no matter whether swapping causes blkio.  Let delayacct
do the similar work.

Link: https://lkml.kernel.org/r/20211112083813.8559-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang 
Reported-by: Zeal Robot 
Cc: Balbir Singh 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

delayacct: Add sysctl to enable at runtime

2021-05-12T09:43:25+00:00

Just like sched_schedstats, allow runtime enabling (and disabling) of
delayacct. This is useful if one forgot to add the delayacct boot time
option.

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

delayacct: Default disabled

2021-05-12T09:43:25+00:00

Assuming this stuff isn't actually used much; disable it by default
and avoid allocating and tracking the task_delay_info structure.

taskstats is changed to still report the regular sched and sched_info
and only skip the missing task_delay_info fields instead of not
reporting anything.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Link: https://lkml.kernel.org/r/20210505111525.308018373@infradead.org

delayacct: Add static_branch in scheduler hooks

2021-05-12T09:43:25+00:00

Cheaper when delayacct is disabled.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Acked-by: Balbir Singh 
Acked-by: Johannes Weiner 
Link: https://lkml.kernel.org/r/20210505111525.248028369@infradead.org

sched: Simplify sched_info_on()

2021-05-12T09:43:24+00:00

The situation around sched_info is somewhat complicated, it is used by
sched_stats and delayacct and, indirectly, kvm.

If SCHEDSTATS=Y (but disabled by default) sched_info_on() is
unconditionally true -- this is the case for all distro kernel configs
I checked.

If for some reason SCHEDSTATS=N, but TASK_DELAY_ACCT=Y, then
sched_info_on() can return false when delayacct is disabled,
presumably because there would be no other users left; except kvm is.

Instead of complicating matters further by accurately accounting
sched_stat and kvm state, simply unconditionally enable when
SCHED_INFO=Y, matching the common distro case.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Acked-by: Johannes Weiner 
Link: https://lkml.kernel.org/r/20210505111525.121458839@infradead.org

delayacct: Use sched_clock()

2021-05-12T09:43:23+00:00

Like all scheduler statistics, use sched_clock() based time.

Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Rik van Riel 
Reviewed-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Acked-by: Johannes Weiner 
Acked-by: Balbir Singh 
Link: https://lkml.kernel.org/r/20210505111525.001031466@infradead.org

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 25

2019-05-21T09:52:39+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it would be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 6 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Steve Winslow 
Reviewed-by: Kate Stewart 
Reviewed-by: Jilayne Lovejoy 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154043.007767574@linutronix.de
Signed-off-by: Greg Kroah-Hartman