From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree Date: Fri, 21 Sep 2012 13:07:33 -0700 Message-ID: <20120921200733.GM7264@google.com> 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 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=gZjex/yCRItgWR2+WP3tX9U5VI4GRjsClsXHYP3z564=; b=i7K2anj08itxWU37bLCeMJF+oStXvr8deJKNhpFvi32/dv5yny2kwGY7823dyofxof J3zswtJNj6zTzJI3GtfluRGhht09KBAJtd7CaWbBY4ekxgFWzR8U3gHq8DTBejZgVP2a zRsjJe4ccO0HiZLfKE7Jdxp9tp/z4DWjXh8PgAuEFQGFdzLBkgDXWyJfwzKKi06jMS6O JTjBbrfBvY60jQ6d8snnHkiQecy6q3SSXjBuFr2a/2NrNIzPptxDDqLNEwccMUfT91qZ z7bboba00WREyWY04I8Pd8fswlBEdXV0X78xr9pTJyHrtomSaclMsASC+AWntmgnrw7i PSZA== Content-Disposition: inline In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Pekka Enberg Cc: Glauber Costa , Christoph Lameter , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Suleiman Souhlal , Frederic Weisbecker , Mel Gorman , David Rientjes , Ingo Molnar , Steven Rostedt Hello, On Fri, Sep 21, 2012 at 12:41:52PM +0300, Pekka Enberg wrote: > > 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. Not necessarily disagreeing, but I don't think it's helpful to set the bar impossibly high. Even static_key doesn't have "exactly *zero*" impact. Let's stick to as minimal as possible when not in use and reasonable in use. And, yeah, this one can be easily solved by using static_key. Thanks. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx146.postini.com [74.125.245.146]) by kanga.kvack.org (Postfix) with SMTP id 95D496B005A for ; Fri, 21 Sep 2012 16:07:38 -0400 (EDT) Received: by pbbro12 with SMTP id ro12so9047794pbb.14 for ; Fri, 21 Sep 2012 13:07:37 -0700 (PDT) Date: Fri, 21 Sep 2012 13:07:33 -0700 From: Tejun Heo Subject: Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree Message-ID: <20120921200733.GM7264@google.com> 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 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: Glauber Costa , Christoph Lameter , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, devel@openvz.org, linux-mm@kvack.org, Suleiman Souhlal , Frederic Weisbecker , Mel Gorman , David Rientjes , Ingo Molnar , Steven Rostedt Hello, On Fri, Sep 21, 2012 at 12:41:52PM +0300, Pekka Enberg wrote: > > 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. Not necessarily disagreeing, but I don't think it's helpful to set the bar impossibly high. Even static_key doesn't have "exactly *zero*" impact. Let's stick to as minimal as possible when not in use and reasonable in use. And, yeah, this one can be easily solved by using static_key. Thanks. -- tejun -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933190Ab2IUUHk (ORCPT ); Fri, 21 Sep 2012 16:07:40 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:34207 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932081Ab2IUUHi (ORCPT ); Fri, 21 Sep 2012 16:07:38 -0400 Date: Fri, 21 Sep 2012 13:07:33 -0700 From: Tejun Heo To: Pekka Enberg Cc: Glauber Costa , Christoph Lameter , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, devel@openvz.org, linux-mm@kvack.org, Suleiman Souhlal , Frederic Weisbecker , Mel Gorman , David Rientjes , Ingo Molnar , Steven Rostedt Subject: Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in kfree Message-ID: <20120921200733.GM7264@google.com> 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 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Fri, Sep 21, 2012 at 12:41:52PM +0300, Pekka Enberg wrote: > > 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. Not necessarily disagreeing, but I don't think it's helpful to set the bar impossibly high. Even static_key doesn't have "exactly *zero*" impact. Let's stick to as minimal as possible when not in use and reasonable in use. And, yeah, this one can be easily solved by using static_key. Thanks. -- tejun