Re: Short sleep precision

From: Andrew Morton
Date: Sun Mar 20 2005 - 08:06:02 EST

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In reply to: Jan Engelhardt: "Re: Short sleep precision"
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Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx> wrote:
>
> I have found that FreeBSD has a very good precision of small sleeps --

Linux nanosleep() used to have a busywait loop for sleeps less than two
milliseconds. 2.4.x still does.

We thought it was stupid and took it out.

> what's holding Linux back from doing the same? Using the code snippet below,
> FBSD yields between 2 and 80 us on the average while Linux is at
> "constantly" ~100 (with HZ=1000) and ~1000 (HZ=100).
>

You can spin on the gettimeofday() result in userspace.
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