From: Manfred Spraul <manfred@colorfullife.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@sgi.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org
Subject: Re: [patch] slab: always follow arch requested alignments
Date: Wed, 26 Jul 2006 20:24:18 +0200 [thread overview]
Message-ID: <44C7B352.9020307@colorfullife.com> (raw)
In-Reply-To: <84144f020607260843i15247ddai7f447f0d9422fec5@mail.gmail.com>
Pekka Enberg wrote:
> Hi Christoph,
>
> On 7/26/06, Christoph Lameter <clameter@sgi.com> wrote:
>
>> We intentionally discard the caller mandated alignment for debugging
>> purposes.
>
>
There are two different types of alignment:
- SLAB_HWCACHE_ALIGN: it's a recommendation, it's regularly ignored.
- the align parameter, or ARCH_SLAB_MINALIGN: It's mandatory. For
example the pgd structures must be 4 kB aligned, it's required by the
hardware. And I think there was (is?) a structure where ptr & ~(size-1)
was used to find the start of the structure.
Thus the patch is correct, it's a bug in the slab allocator. If
HWCACHE_ALIGN is set, then the allocator ignores align or
ARCH_SLAB_MINALIGN.
--
Manfred
next prev parent reply other threads:[~2006-07-26 18:24 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-22 11:06 [patch] slab: always follow arch requested alignments Heiko Carstens
2006-07-22 12:06 ` Pekka Enberg
2006-07-22 14:50 ` Christoph Lameter
2006-07-22 16:26 ` Heiko Carstens
2006-07-22 19:42 ` Christoph Lameter
2006-07-23 7:35 ` Heiko Carstens
2006-07-23 13:03 ` Christoph Lameter
2006-07-23 16:24 ` Heiko Carstens
2006-07-26 8:49 ` Heiko Carstens
2006-07-26 9:55 ` Pekka J Enberg
2006-07-26 8:50 ` [patch 1/2] slab: always consider caller mandated alignment Heiko Carstens
2006-07-26 8:51 ` [patch 2/2] slab: always consider arch " Heiko Carstens
2006-07-26 10:05 ` Pekka J Enberg
2006-07-26 10:13 ` Heiko Carstens
2006-07-26 10:37 ` Pekka J Enberg
2006-07-26 10:52 ` Heiko Carstens
2006-07-26 11:16 ` Pekka J Enberg
2006-07-26 11:26 ` Heiko Carstens
2006-07-26 18:06 ` Manfred Spraul
2006-07-26 18:19 ` Christoph Lameter
2006-07-26 18:45 ` Manfred Spraul
2006-07-26 18:59 ` Christoph Lameter
2006-07-26 19:28 ` Manfred Spraul
2006-07-26 19:31 ` Christoph Lameter
2006-07-26 19:37 ` Manfred Spraul
2006-07-26 19:47 ` Christoph Lameter
2006-07-27 5:33 ` Pekka J Enberg
2006-07-27 5:47 ` Pekka J Enberg
2006-07-27 4:24 ` Pekka J Enberg
2006-07-26 11:22 ` [patch] slab: always follow arch requested alignments Pekka Enberg
2006-07-26 11:29 ` Christoph Lameter
2006-07-26 11:32 ` Pekka J Enberg
2006-07-26 11:41 ` Christoph Lameter
2006-07-26 11:48 ` Pekka J Enberg
2006-07-26 11:49 ` Pekka J Enberg
2006-07-26 11:55 ` Christoph Lameter
2006-07-26 12:05 ` Pekka Enberg
2006-07-26 12:20 ` Christoph Lameter
2006-07-26 12:31 ` Pekka J Enberg
2006-07-26 15:24 ` Christoph Lameter
2006-07-26 15:43 ` Pekka Enberg
2006-07-26 16:25 ` Christoph Lameter
2006-07-26 18:24 ` Manfred Spraul [this message]
2006-07-26 18:28 ` Christoph Lameter
2006-07-26 12:35 ` Pekka J Enberg
2006-07-26 12:36 ` Pekka J Enberg
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