From: Pierre PEIFFER <pierre.peiffer@bull.net>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH] 2.6.16 - futex: small optimization (?)
Date: Thu, 30 Mar 2006 16:51:47 +0200 [thread overview]
Message-ID: <442BF083.2070104@bull.net> (raw)
In-Reply-To: <442AA708.3030802@cosmosbay.com>
Eric Dumazet a écrit :
> I think your analysis is correct Pierre, but you speak of
> 'task-switches', where there is only a spinlock involved :
>
> On UP case : a wake_up_all() wont preempt current thread : it will
> task-switch only when current thread exits kernel mode.
>
> On PREEMPT case : wake_up_all() wont preempt current thread (because
> current thread is holding bh->lock).
>
> On SMP : the awaken thread will spin some time on bh->lock, but not
> task-switch again.
Ok, yes, you're right, thanks.
>
> On RT kernel, this might be different of course...
So, I confirm it only happens on RT kernel ...
... but my patch does not work on those kernels :-/
In fact, I don't really see what's wrong ?
--
Pierre
prev parent reply other threads:[~2006-03-30 14:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-28 7:37 [PATCH] 2.6.16 - futex: small optimization (?) Pierre PEIFFER
2006-03-28 10:05 ` Eric Dumazet
2006-03-28 15:02 ` Ulrich Drepper
2006-03-28 22:46 ` Bill Davidsen
2006-03-29 15:26 ` Ingo Molnar
2006-03-30 20:27 ` Bill Davidsen
2006-03-31 6:01 ` Ingo Molnar
2006-03-31 14:50 ` Bill Davidsen
2006-03-31 18:15 ` Ingo Molnar
2006-03-29 13:18 ` Pierre PEIFFER
2006-03-29 15:26 ` Eric Dumazet
2006-03-30 14:51 ` Pierre PEIFFER [this message]
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