From: Paul Mundt <lethal@linux-sh.org>
To: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Christoph Lameter <cl@linux-foundation.org>,
penberg <penberg@cs.helsinki.fi>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
lkml <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>
Subject: Re: [RFC] slub: ARCH_SLAB_MINALIGN defaults to 8 on x86_32. is this too big?
Date: Thu, 4 Feb 2010 09:07:56 +0900 [thread overview]
Message-ID: <20100204000755.GA451@linux-sh.org> (raw)
In-Reply-To: <1265206946.2118.57.camel@localhost>
On Wed, Feb 03, 2010 at 02:22:26PM +0000, Richard Kennedy wrote:
> Can I define a ARCH_SLAB_MINALIGN in x86_64 to sizeof(void *) ?
> or would it be ok to change the default in slub.c to sizeof(void *) ?
>
Note that this is precisely what ARCH_SLAB_MINALIGN was introduced to
avoid (BYTES_PER_WORD alignment used to be the default for slab, before
ARCH_SLAB_MINALIGN was introduced). Consider the case of 64-bit platforms
using a 32-bit ABI, the native alignment remains 64-bit while sizeof(void
*) == 4. There are a number of (mainly embedded) architectures that
support these sorts of configurations in-tree.
WARNING: multiple messages have this Message-ID (diff)
From: Paul Mundt <lethal@linux-sh.org>
To: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Christoph Lameter <cl@linux-foundation.org>,
penberg <penberg@cs.helsinki.fi>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
lkml <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>
Subject: Re: [RFC] slub: ARCH_SLAB_MINALIGN defaults to 8 on x86_32. is this too big?
Date: Thu, 4 Feb 2010 09:07:56 +0900 [thread overview]
Message-ID: <20100204000755.GA451@linux-sh.org> (raw)
In-Reply-To: <1265206946.2118.57.camel@localhost>
On Wed, Feb 03, 2010 at 02:22:26PM +0000, Richard Kennedy wrote:
> Can I define a ARCH_SLAB_MINALIGN in x86_64 to sizeof(void *) ?
> or would it be ok to change the default in slub.c to sizeof(void *) ?
>
Note that this is precisely what ARCH_SLAB_MINALIGN was introduced to
avoid (BYTES_PER_WORD alignment used to be the default for slab, before
ARCH_SLAB_MINALIGN was introduced). Consider the case of 64-bit platforms
using a 32-bit ABI, the native alignment remains 64-bit while sizeof(void
*) == 4. There are a number of (mainly embedded) architectures that
support these sorts of configurations in-tree.
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next prev parent reply other threads:[~2010-02-04 0:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-03 14:22 [RFC] slub: ARCH_SLAB_MINALIGN defaults to 8 on x86_32. is this too big? Richard Kennedy
2010-02-03 14:22 ` Richard Kennedy
2010-02-03 15:41 ` Christoph Lameter
2010-02-03 15:41 ` Christoph Lameter
2010-02-03 17:25 ` Richard Kennedy
2010-02-03 17:25 ` Richard Kennedy
2010-02-04 16:42 ` Christoph Lameter
2010-02-04 16:42 ` Christoph Lameter
2010-02-04 0:07 ` Paul Mundt [this message]
2010-02-04 0:07 ` Paul Mundt
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