From: Linus Torvalds <torvalds@linux-foundation.org>
To: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH]: Fix SMP-reordering race in mark_buffer_dirty
Date: Wed, 2 Apr 2008 14:35:25 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.1.00.0804021433300.14670@woody.linux-foundation.org> (raw)
In-Reply-To: <alpine.LFD.1.00.0804021422570.14670@woody.linux-foundation.org>
On Wed, 2 Apr 2008, Linus Torvalds wrote:
>
> Core 2 is the outlier in having a noticeably faster "mfence" than atomic
> instructions
Side note: mfence is probably faster than 6 cycles on Core 2. I've seen it
be basically zero-cost. Try adding a few memory ops around it - the timing
will probably change. Core 2 has this odd behaviour that it sometimes does
worse on the *really* trivial things that don't happen in real life.
Linus
next prev parent reply other threads:[~2008-04-02 21:36 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-02 19:20 Mikulas Patocka
2008-04-02 19:44 ` Linus Torvalds
2008-04-02 21:03 ` Mikulas Patocka
2008-04-02 21:31 ` Linus Torvalds
2008-04-02 21:35 ` Linus Torvalds [this message]
2008-04-02 22:39 ` Mikulas Patocka
2008-04-02 22:51 ` Linus Torvalds
2008-04-02 22:35 ` Mikulas Patocka
2008-04-02 22:01 ` Andrew Morton
2008-04-02 22:07 ` Linus Torvalds
2008-04-02 22:53 ` Mikulas Patocka
2008-04-02 23:52 ` Linus Torvalds
2008-04-03 2:12 ` Andrew Morton
2008-04-03 14:34 ` Linus Torvalds
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