Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753511AbZI3KGg (ORCPT ); Wed, 30 Sep 2009 06:06:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752658AbZI3KGg (ORCPT ); Wed, 30 Sep 2009 06:06:36 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:46917 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752588AbZI3KGf (ORCPT ); Wed, 30 Sep 2009 06:06:35 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 30 Sep 2009 19:04:17 +0900 From: KAMEZAWA Hiroyuki To: "linux-mm@kvack.org" Cc: "balbir@linux.vnet.ibm.com" , "nishimura@mxp.nes.nec.co.jp" , "linux-kernel@vger.kernel.org" Subject: [RFC][PATCH 0/2] memcg: replace memcg's per cpu status counter with array counter like vmstat Message-Id: <20090930190417.8823fa44.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (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 Content-Length: 1411 Lines: 35 Hi, In current implementation, memcg uses its own percpu counters for counting evetns and # of RSS, CACHES. Now, counter is maintainer per cpu without any synchronization as vm_stat[] or percpu_counter. So, this is update-is-fast-but-read-is-slow conter. Because "read" for these counter was only done by memory.stat file, I thought read-side-slowness was acceptable. Amount of memory usage, which affects memory limit check, can be read by memory.usage_in_bytes. It's maintained by res_counter. But in current -rc, root memcg's memory usage is calcualted by this per cpu counter and read side slowness may be trouble if it's frequently read. And, in recent discusstion, I wonder we should maintain NR_DIRTY etc... in memcg. So, slow-read-counter will not match our requirements, I guess. I want some counter like vm_stat[] in memcg. This 2 patches are for using counter like vm_stat[] in memcg. Just an idea level implementaion but I think this is not so bad. I confirmed this patch works well. I'm now thinking how to test performance... Any comments are welcome. This patch is onto mmotm + some myown patches...so...this is just an RFC. Regards, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/