linux-kernel - Re: [RFC] hung_task:add detecting task in D state milliseconds timeout

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Message-ID: <20200702174346.GB25523@casper.infradead.org>
Date:   Thu, 2 Jul 2020 18:43:46 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     yang che <chey84736@...il.com>
Cc:     mcgrof@...nel.org, keescook@...omium.org, yzaikin@...gle.com,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [RFC] hung_task:add detecting task in D state milliseconds
 timeout

On Thu, Jul 02, 2020 at 10:08:13PM +0800, yang che wrote:
> current hung_task_check_interval_secs and hung_task_timeout_secs
> only supports seconds.in some cases,the TASK_UNINTERRUPTIBLE state
> takes less than 1 second.The task of the graphical interface,
> the unterruptible state lasts for hundreds of milliseconds
> will cause the interface to freeze

The primary problem I see with this patch is that writing to the
millisecond file silently overrides the setting in the seconds file.
If you end up redoing this patch, there needs to be one variable which
is scaled when reading/writing the seconds file.

Taking a step back though, I think this is the wrong tool for the job.
I'm pretty sure KernelShark will do what you want without any kernel
modifications.