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Message-ID: <1259173636.29779.41.camel@Joe-Laptop.home>
Date: Wed, 25 Nov 2009 10:27:16 -0800
From: Joe Perches <joe@...ches.com>
To: Pekka Enberg <penberg@...helsinki.fi>
Cc: linux-kernel@...r.kernel.org,
Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [PATCH] SLUB: Fix __GFP_ZERO unlikely() annotation
On Wed, 2009-11-25 at 20:21 +0200, Pekka Enberg wrote:
> The unlikely() annotation in slab_alloc() covers too much of the expression.
> It's actually very likely that the object is not NULL so use unlikely() only
> for the __GFP_ZERO expression like SLAB does.
[]
> +++ b/mm/slub.c
> @@ -1735,7 +1735,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
> - if (unlikely((gfpflags & __GFP_ZERO) && object))
> + if (unlikely(gfpflags & __GFP_ZERO) && object)
> memset(object, 0, objsize);
so why not use
if (unlikely(gfpflags & __GFP_ZERO) && likely(object))
--
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