diff options
| author | Yang Yang | 2022-06-01 15:55:25 -0700 |
|---|---|---|
| committer | akpm | 2022-06-01 15:55:25 -0700 |
| commit | 662ce1dc9caf493c309200edbe38d186f1ea20d0 (patch) | |
| tree | e49eeda0a61590b5843d47d1be17dbb18cf3aaa1 /Documentation | |
| parent | 54eb8462f21fb170a05ad64620f0d8d0cf2b7fb5 (diff) | |
delayacct: track delays from write-protect copy
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 <yang.yang29@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reviewed-by: wangyong <wang.yong12@zte.com.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/accounting/delay-accounting.rst | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst index 197fe319cbec..241d1a87f2cd 100644 --- a/Documentation/accounting/delay-accounting.rst +++ b/Documentation/accounting/delay-accounting.rst @@ -15,6 +15,7 @@ c) swapping in pages d) memory reclaim e) thrashing page cache f) direct compact +g) write-protect copy and makes these statistics available to userspace through the taskstats interface. @@ -48,7 +49,7 @@ this structure. See for a description of the fields pertaining to delay accounting. It will generally be in the form of counters returning the cumulative delay seen for cpu, sync block I/O, swapin, memory reclaim, thrash page -cache, direct compact etc. +cache, direct compact, write-protect copy etc. Taking the difference of two successive readings of a given counter (say cpu_delay_total) for a task will give the delay @@ -117,6 +118,8 @@ Get sum of delays, since system boot, for all pids with tgid 5:: 0 0 0ms COMPACT count delay total delay average 0 0 0ms + WPCOPY count delay total delay average + 0 0 0ms Get IO accounting for pid 1, it works only with -p:: |