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From: Ingo Molnar <mingo@elte.hu>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/slab.c : prefetchw the start of new allocated objects
Date: Fri, 29 Jul 2005 12:08:13 +0200	[thread overview]
Message-ID: <20050729100813.GA16129@elte.hu> (raw)
In-Reply-To: <42E9F145.7040302@cosmosbay.com>


* Eric Dumazet <dada1@cosmosbay.com> wrote:

>  	local_irq_restore(save_flags);
>  	objp = cache_alloc_debugcheck_after(cachep, flags, objp, __builtin_return_address(0));
> +	prefetchw(objp);
>  	return objp;

the idea is good, but i'd suggest to do the prefetchw a bit earlier, 
right where we calculate objp. Furthermore, it might make sense to only 
trigger the prefetchw in the alloc-miss (non-per-CPU cache) case. There 
it's almost surely a win, in the per-CPU cache case it's not always.

	Ingo

  parent reply	other threads:[~2005-07-29 10:14 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-07-26 23:35 2.6.12 sound problem Stephen Clark
2005-07-27  4:23 ` Lee Revell
2005-07-27 15:31   ` Stephen Clark
2005-07-27  8:26 ` Takashi Iwai
2005-07-27 15:31   ` Stephen Clark
2005-07-29  8:41     ` Andrew Morton
2005-07-29  9:05       ` [PATCH] mm/slab.c : prefetchw the start of new allocated objects Eric Dumazet
2005-07-29  9:17         ` Andrew Morton
2005-07-29 10:08         ` Ingo Molnar [this message]
2005-07-30 19:31         ` David S. Miller
2005-07-30  3:13       ` 2.6.12 sound problem Stephen Clark
2005-07-30 15:56         ` Stephen Clark
2005-07-31 19:25           ` 2.6.13rc4 hang Stephen Clark
2005-08-01 13:11           ` Stephen Clark

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