linux-kernel - Re: Ques: [kernel/time/*] Is there any disadvantage in using sleep

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Date:	Mon, 7 Dec 2015 19:37:56 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Aniroop Mathur <aniroop.mathur@...il.com>
cc:	John Stultz <john.stultz@...aro.org>, a.mathur@...sung.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Ques: [kernel/time/*] Is there any disadvantage in using
 sleep_range for more than 20ms delay ?

On Mon, 7 Dec 2015, Aniroop Mathur wrote:
> As in the kernel documentation, it is mentioned to use msleep for
> 10ms+ delay, I am confused whether there would be any disadvantage in
> using usleep_range for higher delays values because normally drivers
> have variety of delays used (2, 10, 20, 40, 100, 500 ms).

The real question is how precise must your delay be? If the delay
needs to be precise within the min/max sleep time limits, then
usleep_range() is probably the way to go. If the delay can be
imprecise then using msleep() is the right way because that lets the
kernel batch timers for power saving purposes.

Thanks,

	tglx
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