From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751990Ab0CREjM (ORCPT ); Thu, 18 Mar 2010 00:39:12 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:38508 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751288Ab0CREjL (ORCPT ); Thu, 18 Mar 2010 00:39:11 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 18 Mar 2010 13:35:27 +0900 From: KAMEZAWA Hiroyuki To: balbir@linux.vnet.ibm.com Cc: Andrea Righi , Daisuke Nishimura , Vivek Goyal , Peter Zijlstra , Trond Myklebust , Suleiman Souhlal , Greg Thelen , "Kirill A. Shutemov" , Andrew Morton , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH -mmotm 1/5] memcg: disable irq at page cgroup lock Message-Id: <20100318133527.420b2f25.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100318041944.GA18054@balbir.in.ibm.com> References: <1268609202-15581-1-git-send-email-arighi@develer.com> <1268609202-15581-2-git-send-email-arighi@develer.com> <20100317115855.GS18054@balbir.in.ibm.com> <20100318085411.834e1e46.kamezawa.hiroyu@jp.fujitsu.com> <20100318041944.GA18054@balbir.in.ibm.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 18 Mar 2010 09:49:44 +0530 Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2010-03-18 08:54:11]: > > > On Wed, 17 Mar 2010 17:28:55 +0530 > > Balbir Singh wrote: > > > > > * Andrea Righi [2010-03-15 00:26:38]: > > > > > > > From: KAMEZAWA Hiroyuki > > > > > > > > Now, file-mapped is maintaiend. But more generic update function > > > > will be needed for dirty page accounting. > > > > > > > > For accountig page status, we have to guarantee lock_page_cgroup() > > > > will be never called under tree_lock held. > > > > To guarantee that, we use trylock at updating status. > > > > By this, we do fuzzy accounting, but in almost all case, it's correct. > > > > > > > > > > I don't like this at all, but in almost all cases is not acceptable > > > for statistics, since decisions will be made on them and having them > > > incorrect is really bad. Could we do a form of deferred statistics and > > > fix this. > > > > > > > plz show your implementation which has no performance regresssion. > > For me, I don't neee file_mapped accounting, at all. If we can remove that, > > we can add simple migration lock. > > That doesn't matter, if you need it, I think the larger user base > matters. Unmapped and mapped page cache is critical and I use it > almost daily. > > > file_mapped is a feattue you added. please improve it. > > > > I will, but please don't break it silently > Andrea, could you go in following way ? - don't touch FILE_MAPPED stuff. - add new functions for other dirty accounting stuff as in this series. (using trylock is ok.) Then, no probelm. It's ok to add mem_cgroup_udpate_stat() indpendent from mem_cgroup_update_file_mapped(). The look may be messy but it's not your fault. But please write "why add new function" to patch description. I'm sorry for wasting your time. Thanks, -Kame From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 9C8366B018F for ; Thu, 18 Mar 2010 00:39:19 -0400 (EDT) Received: from m6.gw.fujitsu.co.jp ([10.0.50.76]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o2I4dGIC020975 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 18 Mar 2010 13:39:16 +0900 Received: from smail (m6 [127.0.0.1]) by outgoing.m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 3EF1545DE5A for ; Thu, 18 Mar 2010 13:39:15 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (s6.gw.fujitsu.co.jp [10.0.50.96]) by m6.gw.fujitsu.co.jp (Postfix) with ESMTP id 2A8D845DE4F for ; Thu, 18 Mar 2010 13:39:14 +0900 (JST) Received: from s6.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 45CFCE08001 for ; Thu, 18 Mar 2010 13:39:12 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s6.gw.fujitsu.co.jp (Postfix) with ESMTP id 0CA93E38008 for ; Thu, 18 Mar 2010 13:39:09 +0900 (JST) Date: Thu, 18 Mar 2010 13:35:27 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH -mmotm 1/5] memcg: disable irq at page cgroup lock Message-Id: <20100318133527.420b2f25.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100318041944.GA18054@balbir.in.ibm.com> References: <1268609202-15581-1-git-send-email-arighi@develer.com> <1268609202-15581-2-git-send-email-arighi@develer.com> <20100317115855.GS18054@balbir.in.ibm.com> <20100318085411.834e1e46.kamezawa.hiroyu@jp.fujitsu.com> <20100318041944.GA18054@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: Andrea Righi , Daisuke Nishimura , Vivek Goyal , Peter Zijlstra , Trond Myklebust , Suleiman Souhlal , Greg Thelen , "Kirill A. Shutemov" , Andrew Morton , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Thu, 18 Mar 2010 09:49:44 +0530 Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2010-03-18 08:54:11]: > > > On Wed, 17 Mar 2010 17:28:55 +0530 > > Balbir Singh wrote: > > > > > * Andrea Righi [2010-03-15 00:26:38]: > > > > > > > From: KAMEZAWA Hiroyuki > > > > > > > > Now, file-mapped is maintaiend. But more generic update function > > > > will be needed for dirty page accounting. > > > > > > > > For accountig page status, we have to guarantee lock_page_cgroup() > > > > will be never called under tree_lock held. > > > > To guarantee that, we use trylock at updating status. > > > > By this, we do fuzzy accounting, but in almost all case, it's correct. > > > > > > > > > > I don't like this at all, but in almost all cases is not acceptable > > > for statistics, since decisions will be made on them and having them > > > incorrect is really bad. Could we do a form of deferred statistics and > > > fix this. > > > > > > > plz show your implementation which has no performance regresssion. > > For me, I don't neee file_mapped accounting, at all. If we can remove that, > > we can add simple migration lock. > > That doesn't matter, if you need it, I think the larger user base > matters. Unmapped and mapped page cache is critical and I use it > almost daily. > > > file_mapped is a feattue you added. please improve it. > > > > I will, but please don't break it silently > Andrea, could you go in following way ? - don't touch FILE_MAPPED stuff. - add new functions for other dirty accounting stuff as in this series. (using trylock is ok.) Then, no probelm. It's ok to add mem_cgroup_udpate_stat() indpendent from mem_cgroup_update_file_mapped(). The look may be messy but it's not your fault. But please write "why add new function" to patch description. I'm sorry for wasting your time. Thanks, -Kame -- 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