From: David Howells <dhowells@redhat.com>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@osdl.org, akpm@osdl.org, mingo@redhat.com,
jblunck@suse.de, bcrl@linux.intel.com, matthew@wil.cx,
linux-arch@vger.kernel.org, linuxppc64-dev@ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: Memory barriers and spin_unlock safety
Date: Fri, 03 Mar 2006 16:45:46 +0000 [thread overview]
Message-ID: <1146.1141404346@warthog.cambridge.redhat.com> (raw)
In-Reply-To: <32518.1141401780@warthog.cambridge.redhat.com>
David Howells <dhowells@redhat.com> wrote:
> WRITE mtx
> --> implies SFENCE
Actually, I'm not sure this is true. The AMD64 Instruction Manual's writeup of
SFENCE implies that writes can be reordered, which sort of contradicts what
the AMD64 System Programming Manual says.
If this isn't true, then x86_64 at least should do MFENCE before the store in
spin_unlock() or change the store to be LOCK'ed. The same may also apply for
Pentium3+ class CPUs with the i386 arch.
David
next prev parent reply other threads:[~2006-03-03 16:46 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-03 16:03 Memory barriers and spin_unlock safety David Howells
2006-03-03 16:45 ` David Howells [this message]
2006-03-03 17:03 ` Linus Torvalds
2006-03-03 20:17 ` David Howells
2006-03-03 21:34 ` Linus Torvalds
2006-03-03 21:51 ` Benjamin LaHaise
2006-03-03 22:21 ` Linus Torvalds
2006-03-03 22:36 ` Linus Torvalds
2006-03-07 17:36 ` David Howells
2006-03-07 17:40 ` Matthew Wilcox
2006-03-07 17:56 ` Jesse Barnes
2006-03-07 18:18 ` Alan Cox
2006-03-07 18:28 ` Linus Torvalds
2006-03-07 18:55 ` Alan Cox
2006-03-07 20:21 ` Linus Torvalds
2006-03-03 20:02 ` Arjan van de Ven
2006-03-03 16:55 ` Linus Torvalds
2006-03-03 20:15 ` David Howells
2006-03-03 21:31 ` Linus Torvalds
2006-03-03 21:06 ` Benjamin Herrenschmidt
2006-03-03 21:18 ` Hollis Blanchard
2006-03-03 21:52 ` David S. Miller
2006-03-03 22:04 ` Linus Torvalds
2006-03-04 10:58 ` Paul Mackerras
2006-03-04 22:49 ` Benjamin Herrenschmidt
2006-03-04 10:58 ` Paul Mackerras
2006-03-04 17:28 ` Linus Torvalds
2006-03-08 3:20 ` Paul Mackerras
2006-03-08 3:54 ` Linus Torvalds
2006-03-08 13:12 ` Alan Cox
2006-03-08 15:30 ` Linus Torvalds
2006-03-05 2:04 ` Michael Buesch
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