linux-kernel - Re: [Regression or Fix]perf: profiling stats sigificantly changed for aio_write/read(ext4) between 6.7.0-rc1 and 6.6.0

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Date:   Wed, 15 Nov 2023 18:59:34 +0800 (CST)
From:   "David Wang" <00107082@....com>
To:     "Peter Zijlstra" <peterz@...radead.org>
Cc:     mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, irogers@...gle.com, adrian.hunter@...el.com,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Regression or Fix]perf: profiling stats sigificantly changed
 for aio_write/read(ext4) between 6.7.0-rc1 and 6.6.0



At 2023-11-15 18:32:41, "Peter Zijlstra" <peterz@...radead.org> wrote:
>
>Namhyung, could you please take a look, you know how to operate this
>cgroup stuff.
>

More information,  I run the profiling with 8cpu machine on a SSD with ext4 filesystem :

# mkdir /sys/fs/cgroup/mytest
# echo $$ > /sys/fs/cgroup/mytest/cgroup.procs
## Start profiling targeting cgroup /sys/fs/cgroup/mytest   on another terminal
# fio --randrepeat=1 --ioengine=libaio --direct=1 --name=test  --bs=4k --iodepth=64 --size=1G --readwrite=randrw  --runtime=600 --numjobs=4 --time_based=1

I got a feeling that f06cc667f7990 would decrease total samples by 10%~20% when profiling IO benchmark within cgroup.


David Wang