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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Message-ID: <1a1338d0.6b3a.18bd3c09056.Coremail.00107082@163.com>
Date:   Thu, 16 Nov 2023 00:11:34 +0800 (CST)
From:   "David Wang" <00107082@....com>
To:     "Namhyung Kim" <namhyung@...nel.org>
Cc:     "Peter Zijlstra" <peterz@...radead.org>, mingo@...hat.com,
        acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...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


在 2023-11-15 23:48:33，"Namhyung Kim" <namhyung@...nel.org> 写道：
>On Wed, Nov 15, 2023 at 3:00 AM David Wang <00107082@....com> wrote:
>>
>>
>>
>> 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.
>
>Oh sorry, I missed this message.  Can you please share the
>command line and the output?
>
I did not use perf..... This is the part where  it is not quite convincing to report the change, I am using a profiling tool of my own as I mentioned in the first mail.....
But I believe my profiling tools did detect some changes.

I am not experienced with the perf-tool at all,   too complicated a tool for me.... But I think I can try it.

David Wang.