From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 23 Oct 2008 10:39:58 -0500 (CDT) From: Christoph Lameter 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 Sender: owner-linux-mm@kvack.org Return-Path: 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 List-ID: 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, 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