From: Clemens Ladisch <clemens@ladisch.de>
To: Aniroop Mathur <aniroop.mathur@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
a.mathur@samsung.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Ques: [kernel/time/*] Is there any disadvantage in using usleep_range for more than 20ms delay ?
Date: Tue, 8 Dec 2015 10:03:59 +0100 [thread overview]
Message-ID: <56669CFF.8040806@ladisch.de> (raw)
In-Reply-To: <CADYu308GqGO8C2UA1H39u0ASBmRYcaOJD2pGEK2NenqtED_WhA@mail.gmail.com>
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
next prev parent reply other threads:[~2015-12-08 9:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-07 17:59 Ques: [kernel/time/*] Is there any disadvantage in using usleep_range for more than 20ms delay ? Aniroop Mathur
2015-12-08 9:03 ` Clemens Ladisch [this message]
2015-12-08 19:21 ` Aniroop Mathur
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