From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qe0-f48.google.com (mail-qe0-f48.google.com [209.85.128.48]) by kanga.kvack.org (Postfix) with ESMTP id F3C4B6B003B for ; Thu, 16 Jan 2014 11:44:29 -0500 (EST) Received: by mail-qe0-f48.google.com with SMTP id ne12so900598qeb.21 for ; Thu, 16 Jan 2014 08:44:29 -0800 (PST) Received: from qmta13.emeryville.ca.mail.comcast.net (qmta13.emeryville.ca.mail.comcast.net. [2001:558:fe2d:44:76:96:27:243]) by mx.google.com with ESMTP id t5si10363257qak.16.2014.01.16.08.44.27 for ; Thu, 16 Jan 2014 08:44:29 -0800 (PST) Date: Thu, 16 Jan 2014 10:44:24 -0600 (CST) From: Christoph Lameter Subject: Re: [PATCH 0/9] re-shrink 'struct page' when SLUB is on. In-Reply-To: <52D5B48D.30006@sr71.net> Message-ID: References: <20140103180147.6566F7C1@viggo.jf.intel.com> <20140103141816.20ef2a24c8adffae040e53dc@linux-foundation.org> <20140106043237.GE696@lge.com> <52D05D90.3060809@sr71.net> <20140110153913.844e84755256afd271371493@linux-foundation.org> <52D0854F.5060102@sr71.net> <20140113014408.GA25900@lge.com> <52D41F52.5020805@sr71.net> <52D5B48D.30006@sr71.net> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Joonsoo Kim , Pekka Enberg , Andrew Morton , "linux-mm@kvack.org" , LKML On Tue, 14 Jan 2014, Dave Hansen wrote: > On 01/14/2014 12:07 PM, Christoph Lameter wrote: > > One easy way to shrink struct page is to simply remove the feature. The > > patchset looked a bit complicated and does many other things. > > Sure. There's a clear path if you only care about 'struct page' size, > or if you only care about making the slub fast path as fast as possible. > We've got three variables, though: > > 1. slub fast path speed The fast path does use this_cpu_cmpxchg_double which is something different from a cmpxchg_double and its not used on struct page. > Arranged in three basic choices: > > 1. Big 'struct page', fast, medium complexity code > 2. Small 'struct page', slow, lowest complexity The numbers that I see seem to indicate that a big struct page means slow. > The question is what we should do by _default_, and what we should be > recommending for our customers via the distros. Are you saying that you > think we should completely rule out even having option 1 in mainline? If option 1 is slower than option 2 then we do not need it. -- 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