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Date: Thu, 4 Feb 2010 09:07:56 +0900
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?
Message-ID: <20100204000755.GA451@linux-sh.org>
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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.