From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx163.postini.com [74.125.245.163]) by kanga.kvack.org (Postfix) with SMTP id 99BF76B002B for ; Fri, 21 Sep 2012 05:41:55 -0400 (EDT) Received: by lbbgj10 with SMTP id gj10so4193812lbb.14 for ; Fri, 21 Sep 2012 02:41:53 -0700 (PDT) Date: Fri, 21 Sep 2012 12:41:52 +0300 (EEST) From: Pekka Enberg Subject: Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree In-Reply-To: <505C33D3.5000202@parallels.com> Message-ID: References: <1347977530-29755-1-git-send-email-glommer@parallels.com> <1347977530-29755-10-git-send-email-glommer@parallels.com> <00000139d9fe8595-8905906d-18ed-4d41-afdb-f4c632c2d50a-000000@email.amazonses.com> <5059777E.8060906@parallels.com> <505C33D3.5000202@parallels.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: Christoph Lameter , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, devel@openvz.org, Tejun Heo , linux-mm@kvack.org, Suleiman Souhlal , Frederic Weisbecker , Mel Gorman , David Rientjes , Ingo Molnar , Steven Rostedt On Fri, 21 Sep 2012, Glauber Costa wrote: > > We should assume that most distributions enable CONFIG_MEMCG_KMEM, > > right? Therfore, any performance impact should be dependent on whether > > or not kmem memcg is *enabled* at runtime or not. > > > > Can we use the "static key" thingy introduced by tracing folks for this? > > Yes. > > I am already using static keys extensively in this patchset, and that is > how I intend to handle this particular case. Cool. The key point here is that !CONFIG_MEMCG_KMEM should have exactly *zero* performance impact and CONFIG_MEMCG_KMEM disabled at runtime should have absolute minimal impact. 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