linux-kernel - Re: [patch] CFS scheduler, -v19

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Message-ID: <20070717074537.GA13539@elte.hu>
Date:	Tue, 17 Jul 2007 09:45:37 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Ian Kent <raven@...maw.net>
Cc:	Chuck Ebbert <cebbert@...hat.com>,
	Bill Davidsen <davidsen@....com>, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [patch] CFS scheduler, -v19


* Ian Kent <raven@...maw.net> wrote:

> Yes it does and I have two reported bugs so far.
> 
> In several places I have code similar to:
> 
> wait.tv_sec = time(NULL) + 1;
> wait.tv_nsec = 0;
> 
> signaled = 0;
> while (!signaled) {
>         status = pthread_cond_timedwait(&cond, &mutex, &wait);
>        if (status) {
>              if (status == ETIMEDOUT)
>                   break;
>              fatal(status);
>       }
> }

ah! It passes in a low-res time source into a high-res time interface 
(pthread_cond_timedwait()). Could you change the time(NULL) + 1 to 
time(NULL) + 2, or change it to:

	gettimeofday(&wait, NULL);
	wait.tv_sec++;

does this solve the spinning?

i'm wondering how widespread this is. If automount is the only app doing 
this then _maybe_ we could get away with it by changing automount?

	Ingo
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