From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f181.google.com (mail-ob0-f181.google.com [209.85.214.181]) by kanga.kvack.org (Postfix) with ESMTP id 2D958828DF for ; Thu, 14 Jan 2016 11:21:55 -0500 (EST) Received: by mail-ob0-f181.google.com with SMTP id is5so87165740obc.0 for ; Thu, 14 Jan 2016 08:21:55 -0800 (PST) Received: from mail-ob0-x244.google.com (mail-ob0-x244.google.com. [2607:f8b0:4003:c01::244]) by mx.google.com with ESMTPS id p4si8262553oib.73.2016.01.14.08.21.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 14 Jan 2016 08:21:54 -0800 (PST) Received: by mail-ob0-x244.google.com with SMTP id is5so8879996obc.3 for ; Thu, 14 Jan 2016 08:21:54 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1452749069-15334-1-git-send-email-iamjoonsoo.kim@lge.com> <1452749069-15334-10-git-send-email-iamjoonsoo.kim@lge.com> Date: Fri, 15 Jan 2016 01:21:54 +0900 Message-ID: Subject: Re: [PATCH 09/16] mm/slab: put the freelist at the end of slab page From: Joonsoo Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Andrew Morton , Pekka Enberg , David Rientjes , Joonsoo Kim , Jesper Dangaard Brouer , Linux Memory Management List , LKML 2016-01-15 0:26 GMT+09:00 Christoph Lameter : > On Thu, 14 Jan 2016, Joonsoo Kim wrote: > >> Currently, the freelist is at the front of slab page. This requires >> extra space to meet object alignment requirement. If we put the freelist >> at the end of slab page, object could start at page boundary and will >> be at correct alignment. This is possible because freelist has >> no alignment constraint itself. >> >> This gives us two benefits. It removes extra memory space >> for the freelist alignment and remove complex calculation >> at cache initialization step. I can't think notable drawback here. > > > The third one is that the padding space at the end of the slab could > actually be used for the freelist if it fits. Yes. > The drawback may be that the location of the freelist at the beginning of > the page is more cache effective because the cache prefetcher may be able > to get the following cachelines and effectively hit the first object. > However, this is rather dubious speculation. I think so, too. :) If then, could you give me an ack? Thanks. -- 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