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From: Andrew Morton <akpm@osdl.org>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Short sleep precision
Date: Sun, 20 Mar 2005 05:04:03 -0800	[thread overview]
Message-ID: <20050320050403.672bf30a.akpm@osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.61.0503201316320.18044@yvahk01.tjqt.qr>

Jan Engelhardt <jengelh@linux01.gwdg.de> 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.

      parent reply	other threads:[~2005-03-20 13:04 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-20 12:25 Short sleep precision Jan Engelhardt
2005-03-20 12:44 ` Jesper Juhl
2005-03-20 13:34   ` Jan Engelhardt
2005-03-21 16:35     ` Chris Friesen
2005-03-22  2:46       ` Robert White
2005-03-22  7:46       ` Jan Engelhardt
     [not found]         ` <424036AE.1040404@nortel.com>
2005-03-22 15:19           ` Jan Engelhardt
2005-03-20 13:04 ` Andrew Morton [this message]

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