Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755699AbYJWPlA (ORCPT ); Thu, 23 Oct 2008 11:41:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752200AbYJWPku (ORCPT ); Thu, 23 Oct 2008 11:40:50 -0400 Received: from nlpi053.sbcis.sbc.com ([207.115.36.82]:54334 "EHLO nlpi053.prodigy.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751318AbYJWPkt (ORCPT ); Thu, 23 Oct 2008 11:40:49 -0400 Date: Thu, 23 Oct 2008 10:39:58 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@quilx.com To: Eric Dumazet cc: Pekka Enberg , Miklos Szeredi , nickpiggin@yahoo.com.au, hugh@veritas.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: Re: SLUB defrag pull request? In-Reply-To: <49009575.60004@cosmosbay.com> Message-ID: References: <1223883004.31587.15.camel@penberg-laptop> <84144f020810221348j536f0d84vca039ff32676e2cc@mail.gmail.com> <1224745831.25814.21.camel@penberg-laptop> <84144f020810230658o7c6b3651k2d671aab09aa71fb@mail.gmail.com> <84144f020810230714g7f5d36bas812ad691140ee453@mail.gmail.com> <49009575.60004@cosmosbay.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Spam-Score: -2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 853 Lines: 20 On Thu, 23 Oct 2008, Eric Dumazet wrote: > At alloc time, I remember I added a prefetchw() call in SLAB in > __cache_alloc(), > this could explain some differences between SLUB and SLAB too, since SLAB > gives a hint to processor to warm its cache. SLUB touches objects by default when allocating. And it does it immediately in slab_alloc() in order to retrieve the pointer to the next object. So there is no point of hinting there right now. If we go to the pointer arrays then the situation is similar to SLAB where the object is not touched by the allocator. Then the hint would be useful again. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/