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From: Yafang Shao <laoar.shao@gmail.com>
Date: Tue, 8 Aug 2017 16:50:23 +0800
Message-ID: <CALOAHbB2k-Ks_qvb0WW_9_h1Y2=DNOHC1hWf3MgPPEqt-xT0Hg@mail.gmail.com>
Subject: Re: [PATCH v2] scheduler: enhancement to show_state_filter
To: Peter Zijlstra <peterz@infradead.org>
Cc: gregkh@linuxfoundation.org, jslaby@suse.com, mingo@redhat.com,
        linux-kernel@vger.kernel.org
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Hi Peter,

The point is we call use it as bellow,
    show_state_filter(TASK_RUNNING);
because TASK_RUNNING is 0, that will dump all tasks.

Under some circumstance, we need this to dump only tasks in TASK_RUNNING state.

Thanks
Yafang

2017-08-08 16:30 GMT+08:00 Peter Zijlstra <peterz@infradead.org>:
> On Tue, Aug 08, 2017 at 08:53:10PM +0800, Yafang Shao wrote:
>> Sometimes we want to get tasks in TASK_RUNNING sepcifically,
>> instead of dump all tasks.
>> For example, when the loadavg are high, we want to dump
>> tasks in TASK_RUNNING and TASK_UNINTERRUPTIBLE, which contribute
>> to system load. But mostly there're lots of tasks in Sleep state,
>> which occupies almost all of the kernel log buffer, even overflows
>> it, that causes the useful messages get lost. Although we can
>> enlarge the kernel log buffer, but that's not a good idea.
>>
>> So I made this change to make the show_state_filter more flexible,
>> and then we can dump the tasks in TASK_RUNNING specifically.
>
> It reads like magic and I really don't see the point.