From: Ingo Molnar <mingo@elte.hu>
To: Peter Williams <pwil3058@bigpond.net.au>
Cc: Linus Torvalds <torvalds@osdl.org>, Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org
Subject: Re: [patch, 2.6.10-rc2] sched: fix ->nr_uninterruptible handling bugs
Date: Wed, 17 Nov 2004 00:28:27 +0100 [thread overview]
Message-ID: <20041116232827.GA842@elte.hu> (raw)
In-Reply-To: <419A7D09.4080001@bigpond.net.au>
* Peter Williams <pwil3058@bigpond.net.au> wrote:
> Couldn't this part of the problem have been solved by using an
> atomic_t for nr_uninterruptible as for nr_iowait? It would also
> remove the need for migrate_nr_uninterruptible().
maybe, but why? Atomic ops are still a tad slower than normal ops and
every cycle counts in the wakeup path. Also, the solution is still not
correct, because it does not take other migration paths into account, so
we could end up with a sleeping task showing up on another CPU just as
well. The most robust solution is to simply not care about migration and
to care about the total count only.
Ingo
next prev parent reply other threads:[~2004-11-16 22:27 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-11-16 11:32 [patch, 2.6.10-rc2] sched: fix ->nr_uninterruptible handling bugs Ingo Molnar
2004-11-16 22:19 ` Peter Williams
2004-11-16 23:28 ` Ingo Molnar [this message]
2004-11-16 23:10 ` Linus Torvalds
2004-11-17 10:26 ` Ingo Molnar
2004-11-17 15:52 ` Linus Torvalds
2004-11-18 16:21 ` Ingo Molnar
2005-01-28 0:53 ` Paul Jackson
2005-01-28 1:06 ` Linus Torvalds
2005-01-28 2:14 ` Paul Jackson
2005-01-28 4:28 ` Ingo Molnar
2005-01-28 5:18 ` Paul Jackson
2005-01-28 6:01 ` Andi Kleen
2004-11-16 23:48 ` Peter Williams
2004-11-16 22:49 ` Nick Piggin
2004-11-16 23:03 ` Nick Piggin
2004-11-16 23:32 ` Peter Williams
2004-11-16 23:37 ` Nick Piggin
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