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Subject[PATCH] Documentation: accounting: add thrashing page cache and direct compact
Date
From: wangyong <wang.yong12@zte.com.cn>

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/

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: wangyong <wang.yong12@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
---
Documentation/accounting/delay-accounting.rst | 55 +++++++++++++--------------
1 file changed, 27 insertions(+), 28 deletions(-)

diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst
index 1b8b46d..197fe31 100644
--- a/Documentation/accounting/delay-accounting.rst
+++ b/Documentation/accounting/delay-accounting.rst
@@ -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
-
-
- 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
+ # ./getdelays -d -t 5
+ print delayacct stats ON
+ TGID 5

-Get delays seen in executing a given simple command::

- # ./getdelays -c ls /
+ 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

- bin data1 data3 data5 dev home media opt root srv sys usr
- boot data2 data4 data6 etc lib mnt proc sbin subdomain tmp var
+Get IO accounting for pid 1, it works only with -p::

+ # ./getdelays -i -p 1
+ printing IO accounting
+ linuxrc: read=65536, write=0, cancelled_write=0

- 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.
--
2.7.4
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