linux-kernel - Re: [RFC PATCH v2 4/8] tick/nohz: keep tick on for a fast idle

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Message-ID: <39e58dd5-1abd-aac7-2577-9afa71236e35@linux.intel.com>
Date:   Mon, 16 Oct 2017 14:31:41 +0800
From:   "Li, Aubrey" <aubrey.li@...ux.intel.com>
To:     Mike Galbraith <efault@....de>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Aubrey Li <aubrey.li@...el.com>
Cc:     tglx@...utronix.de, peterz@...radead.org, len.brown@...el.com,
        ak@...ux.intel.com, tim.c.chen@...ux.intel.com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 4/8] tick/nohz: keep tick on for a fast idle

On 2017/10/16 14:25, Mike Galbraith wrote:
> On Mon, 2017-10-16 at 13:34 +0800, Li, Aubrey wrote:
>> On 2017/10/16 12:45, Mike Galbraith wrote:
>>> On Mon, 2017-10-16 at 11:26 +0800, Li, Aubrey wrote:
>>>>
>>>> I'll try to move quiet_vmstat() into the normal idle branch if this patch series
>>>> are reasonable. Is fast_idle a good indication for it?
>>>
>>> see x86_tip 62cb1188ed86 sched/idle: Move quiet_vmstate() into the NOHZ code
>>
>> It looks like this commit makes tick stop critical as it can be invoked in interrupt
>> exit path?
> 
> do_idle() ain't critical?  It is in my book.  Hopefully, you're about
> to make that idle_stat.fast_idle thingy liberal enough that we cease
> mucking about with the tick on every microscopic idle (and I can then
> trash my years old local patch to avoid needlessly eating that cost).
> 

Welcome any feedback of other patch set, Mike, :)

Thanks,
-Aubrey