linux-kernel - How to debug high sysload in 2,3 seconds

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Message-ID: <CANpxKHEb2ZWT-bBkZa0+XKS49d9iUEcXztQd+Wh+VC9Vh2=w3w@mail.gmail.com>
Date:   Mon, 15 May 2023 19:59:37 +1000
From:   Naruto Nguyen <narutonguyen2018@...il.com>
To:     kernel derkeiler <linux-kernel@...r.kernel.org>
Subject: How to debug high sysload in 2,3 seconds

Hi everyone,

My system during idle sometimes has high sysload in 2,3 seconds
(around 70% sysload) and then come back to normal after that. I see it
happen in some conditions and try to use top commands to debug and see
one of processes in my system consume CPU.

I would like to investigate more what code causes CPU high. However
the spike only happens 2,3 seconds so I have no ideas to continue
debugging. I thought about perf tool, but I am not sure how to profile
with perf to identify exactly what happens in 2,3 seconds during high
CPU. Because I can reproduce the issue to see it, but only during 3 or
4 minutes, I can see CPU increase in 2,3 seconds. So I worry that
using perf to profile in 3,4 minutes cannot identify the code causing
CPU increase in a short time.

Could you help to advise how I can debug in this case?

Thanks,
Brs,
Naruto