From: Eric Dumazet <eric.dumazet@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
rientjes@google.com, hughd@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [GIT PULL] Lockless SLUB slowpaths for v3.1-rc1
Date: Sat, 30 Jul 2011 08:33:28 +0200 [thread overview]
Message-ID: <1312007608.2873.77.camel@edumazet-laptop> (raw)
In-Reply-To: <m2pqksznea.fsf@firstfloor.org>
Le vendredi 29 juillet 2011 A 16:18 -0700, Andi Kleen a A(C)crit :
> Christoph Lameter <cl@linux.com> writes:
>
> > On Fri, 29 Jul 2011, Pekka Enberg wrote:
> >
> >> We haven't come up with a solution to keep struct page size the same but I
> >> think it's a reasonable trade-off.
> >
> > The change requires the page struct to be aligned to a double word
> > boundary.
>
> Why is that?
>
Because cmpxchg16b is believed to require a 16bytes alignment.
http://siyobik.info/main/reference/instruction/CMPXCHG8B%2FCMPXCHG16B
64-Bit Mode Exceptions
...
#GP(0) If the memory address is in a non-canonical form. If memory
operand for CMPXCHG16B is not aligned on a 16-byte boundary. If
CPUID.01H:ECX.CMPXCHG16B[bit 13] = 0.
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next prev parent reply other threads:[~2011-07-30 6:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-28 22:47 Pekka Enberg
2011-07-29 15:04 ` Christoph Lameter
2011-07-29 23:18 ` Andi Kleen
2011-07-30 6:33 ` Eric Dumazet [this message]
2011-07-31 18:50 ` David Rientjes
2011-07-31 20:24 ` David Rientjes
2011-07-31 20:45 ` Pekka Enberg
2011-07-31 21:55 ` David Rientjes
2011-08-01 5:08 ` Pekka Enberg
2011-08-01 10:02 ` David Rientjes
2011-08-01 12:45 ` Pekka Enberg
2011-08-02 2:43 ` David Rientjes
2011-08-01 12:06 ` Pekka Enberg
2011-08-01 15:55 ` Christoph Lameter
2011-08-02 4:05 ` David Rientjes
2011-08-02 14:15 ` Christoph Lameter
2011-08-02 16:24 ` David Rientjes
2011-08-02 16:36 ` Christoph Lameter
2011-08-02 20:02 ` David Rientjes
2011-08-03 14:09 ` Christoph Lameter
2011-08-08 20:04 ` David Rientjes
2011-07-30 18:27 ` Linus Torvalds
2011-07-30 18:32 ` Linus Torvalds
2011-07-31 17:39 ` Andi Kleen
2011-08-01 0:22 ` KAMEZAWA Hiroyuki
2011-07-31 18:11 ` David Rientjes
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