linux-kernel - Re: [PATCH] use 64bit timer for hpet

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Date:   Mon, 12 Jul 2021 09:25:38 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linux <zhaoyan.liao@...ux.alibaba.com>
Cc:     mingo@...hat.com, hpa@...or.com, dwmw@...zon.co.uk,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        songmuchun@...edance.com, likunkun@...edance.com,
        guancheng.rjk@...baba-inc.com, duanxiongchun@...edance.com,
        wenan.mao@...ux.alibaba.com
Subject: Re: [PATCH] use 64bit timer for hpet

Liao,

On Mon, Jul 12 2021 at 12:52, Linux wrote:
>> Sorry, keeping the softirq from running for 3 minutes is simply out of
>> spec. If the sysadmin decides to do so, then he can keep the pieces.
>
> It is because the kernel thread is busy that the clocksource_watchdog 
> thread is not scheduled, not softirq.

Which thread?

The clocksource watchdog runs from a timer_list timer callback in
softirq context. Even if the softirq is switched to the softirq thread
then still my argument of starving that for 3 minutes still stands.

This is _not_ a kernel problem. Overcommitment is a admin problem.

Thanks,

        tglx