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Message-ID: <56669CFF.8040806@ladisch.de> Date: Tue, 8 Dec 2015 10:03:59 +0100 From: Clemens Ladisch <clemens@...isch.de> To: Aniroop Mathur <aniroop.mathur@...il.com> Cc: John Stultz <john.stultz@...aro.org>, Thomas Gleixner <tglx@...utronix.de>, 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 usleep_range for more than 20ms delay ? 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). > > So, could you please help to confirm that if we use usleep_range for > inserting delays greater than 20 ms, would it be harmful or beneficial > or does not make any difference at all ? As the documentation told you, usleep_range() is likely to require a separate interrupt, while msleep() is likely to round to some other, already-scheduled interrupt. The former is possibly harmful regarding CPU and power usage; you have to balance it against your need for accuracy. (And usleep_range() has a 32-bit nanosecond limit on 32-bit architectures.) Regards, Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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