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Documentation/accounting/delay-accounting.rst: add thrashing page cache and direct compact 

Add thrashing page cache and direct compact related descriptions and
update the usage of getdelays userspace utility.

The following patches modifications have been updated:
https://lore.kernel.org/all/20190312102002.31737-4-jinpuwang@gmail.com/
https://lore.kernel.org/all/1638619795-71451-1-git-send-email-
wang.yong12@zte.com.cn/

Link: https://lkml.kernel.org/r/1639583021-92977-1-git-send-email-wang.yong12@zte.com.cn
Signed-off-by: wangyong <wang.yong12@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
wangyong 2022-01-19 18:10:12 -08:00 committed by Linus Torvalds
parent 1193829da1
commit ec710aa8b2
1 changed files with 27 additions and 28 deletions
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55
Documentation/accounting/delay-accounting.rst
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@ -13,6 +13,8 @@ a) waiting for a CPU (while being runnable)
b) completion of synchronous block I/O initiated by the task
c) swapping in pages
d) memory reclaim
e) thrashing page cache
f) direct compact
and makes these statistics available to userspace through
the taskstats interface.
@ -41,11 +43,12 @@ generic data structure to userspace corresponding to per-pid and per-tgid
statistics. The delay accounting functionality populates specific fields of
this structure. See
include/linux/taskstats.h
include/uapi/linux/taskstats.h
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 etc.
delay seen for cpu, sync block I/O, swapin, memory reclaim, thrash page
cache, direct compact etc.
Taking the difference of two successive readings of a given
counter (say cpu_delay_total) for a task will give the delay
@ -88,41 +91,37 @@ seen.
General format of the getdelays command::
getdelays [-t tgid] [-p pid] [-c cmd...]
getdelays [-dilv] [-t tgid] [-p pid]
Get delays, since system boot, for pid 10::
# ./getdelays -p 10
# ./getdelays -d -p 10
(output similar to next case)
Get sum of delays, since system boot, for all pids with tgid 5::
# ./getdelays -t 5
# ./getdelays -d -t 5
print delayacct stats ON
TGID 5
CPU count real total virtual total delay total
7876 92005750 100000000 24001500
IO count delay total
0 0
SWAP count delay total
0 0
RECLAIM count delay total
0 0
CPU count real total virtual total delay total delay average
8 7000000 6872122 3382277 0.423ms
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
0 0 0ms
Get delays seen in executing a given simple command::
Get IO accounting for pid 1, it works only with -p::
# ./getdelays -c ls /
# ./getdelays -i -p 1
printing IO accounting
linuxrc: read=65536, write=0, cancelled_write=0
bin data1 data3 data5 dev home media opt root srv sys usr
boot data2 data4 data6 etc lib mnt proc sbin subdomain tmp var
CPU count real total virtual total delay total
6 4000250 4000000 0
IO count delay total
0 0
SWAP count delay total
0 0
RECLAIM count delay total
0 0
The above command can be used with -v to get more debug information.