linux-kernel - Re: [RESEND PATCH v2 2/2] power/idle: enhance the precision of sleep

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Message-ID: <CAN2waFt8u7HX9GC0SMeRtc2AB3SN=yu7GLbVHY5O6DtK4GFZeQ@mail.gmail.com>
Date:	Thu, 23 Jun 2016 16:34:28 +0800
From:	Zhaoyang Huang <zhaoyang.huang@...aro.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Geng Ren <geng.ren@...eadtrum.com>,
	Alex Wang <alex.wang@...eadtrum.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	mingo@...hat.com, peterz@...radead.org,
	Zhaoyang Huang (黄朝阳) 
	<zhaoyang.huang@...eadtrum.com>
Subject: Re: [RESEND PATCH v2 2/2] power/idle: enhance the precision of sleep_length

On 23 June 2016 at 16:18, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Thu, 23 Jun 2016, Zhaoyang Huang wrote:
>> On 23 June 2016 at 15:01, Thomas Gleixner <tglx@...utronix.de> wrote:
>> Thomas, I agree with you, I have discussed the modification with the
>> call back owner. However, I wonder if we can make the idle's framework
>> to be more precised without the assumption of short CPU_PM_ENTER
>> callbacks. Thank you!
>
> What's the point? To help people who put insanities into the idle code path?
>
> Thanks,
>
>         tglx
>
Hi, Thomas. If the entry,exit,min time of one idle state sums up to
500us in some platform, the 100us callback which should be common as
caused by cache miss would also generate 20% imprecision. Don't you
think it is a case we should deal with?