From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: SLUB defrag pull request? From: Pekka Enberg 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 Sender: owner-linux-mm@kvack.org Return-Path: 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org