Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754082AbYJ1LGg (ORCPT ); Tue, 28 Oct 2008 07:06:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752756AbYJ1LG0 (ORCPT ); Tue, 28 Oct 2008 07:06:26 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:49594 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752231AbYJ1LGY (ORCPT ); Tue, 28 Oct 2008 07:06:24 -0400 Subject: Re: SLUB defrag pull request? From: Pekka Enberg To: Eric Dumazet Cc: Christoph Lameter , 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 In-Reply-To: <4900B0EF.2000108@cosmosbay.com> 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> <4900A7C8.9020707@cosmosbay.com> <4900B0EF.2000108@cosmosbay.com> Date: Tue, 28 Oct 2008 13:06:23 +0200 Message-Id: <1225191983.27477.16.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit X-Mailer: Evolution 2.22.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1077 Lines: 28 On Thu, 2008-10-23 at 19:14 +0200, Eric Dumazet wrote: > [PATCH] slub: slab_alloc() can use prefetchw() > > Most kmalloced() areas are initialized/written right after allocation. > > prefetchw() gives a hint to cpu saying this cache line is going to be > *modified*, even if first access is a read. > > Some architectures can save some bus transactions, acquiring > the cache line in an exclusive way instead of shared one. > > Same optimization was done in 2005 on SLAB in commit > 34342e863c3143640c031760140d640a06c6a5f8 > ([PATCH] mm/slab.c: prefetchw the start of new allocated objects) > > Signed-off-by: Eric Dumazet Christoph, I was sort of expecting a NAK/ACK from you before merging this. I would be nice to have numbers on this but then again I don't see how this can hurt either. Pekka -- 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/