From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Valdis.Kletnieks@vt.edu
Cc: Cyrill Gorcunov <gorcunov@gmail.com>,
Christoph Lameter <cl@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: mm: slab - __cache_alloc NULL prefetch fix
Date: Thu, 20 Nov 2008 22:03:37 +0200 [thread overview]
Message-ID: <4925C299.6070907@cs.helsinki.fi> (raw)
In-Reply-To: <28180.1227211108@turing-police.cc.vt.edu>
Valdis.Kletnieks@vt.edu wrote:
> On Thu, 20 Nov 2008 19:44:00 +0300, Cyrill Gorcunov said:
>
>> - prefetchw(objp);
>>
>> - if (likely(objp))
>> + if (likely(objp)) {
>> + prefetchw(objp);
>> kmemcheck_slab_alloc(cachep, flags, objp, obj_size(cachep));
>> + }
>
> Although it probably makes sense to not bother prefetching NULL, I also
> need to wonder how useful it is to prefetch something that we then
> turn around and dereference in the very next line of code.
Note that kmemcheck_slab_alloc() is going to be a no-op on anything but
a special developer or tester debug config.
next prev parent reply other threads:[~2008-11-20 20:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-20 16:44 mm: slab - __cache_alloc NULL prefetch fix Cyrill Gorcunov
2008-11-20 17:01 ` Cyrill Gorcunov
2008-11-20 18:16 ` Christoph Lameter
2008-11-20 18:24 ` Cyrill Gorcunov
2008-11-20 18:15 ` Christoph Lameter
2008-11-20 19:58 ` Valdis.Kletnieks
2008-11-20 20:03 ` Pekka Enberg [this message]
2008-11-20 20:10 ` Cyrill Gorcunov
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