From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753631AbXCZKcB (ORCPT ); Mon, 26 Mar 2007 06:32:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753636AbXCZKcB (ORCPT ); Mon, 26 Mar 2007 06:32:01 -0400 Received: from mailx.hitachi.co.jp ([133.145.228.49]:60056 "EHLO mailx.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753631AbXCZKcA (ORCPT ); Mon, 26 Mar 2007 06:32:00 -0400 Message-ID: <4607A01D.1060401@hitachi.com> Date: Mon, 26 Mar 2007 19:27:41 +0900 From: Tomoki Sekiyama User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) MIME-Version: 1.0 To: Bill Davidsen , Andrew Morton Cc: linux-kernel@vger.kernel.org, yumiko.sugita.yf@hitachi.com, masami.hiramatsu.pt@hitachi.com, hidehiro.kawai.ez@hitachi.com, yuji.kakutani.uw@hitachi.com, soshima@redhat.com, haoki@redhat.com, kamezawa.hiroyu@jp.fujitsu.com, nikita@clusterfs.com, leroy.vanlogchem@wldelft.nl Subject: Re: [PATCH 0/3] VM throttling: avoid blocking occasional writers References: <45F7EDC6.5090303@hitachi.com> <20070315110745.af867b10.akpm@linux-foundation.org> <45FD53DB.5000207@tmr.com> <460218D2.40701@hitachi.com> <46026B78.3080401@tmr.com> In-Reply-To: <46026B78.3080401@tmr.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, Thanks for your reply. >>3) Use "dirty_ratio" as the blocking ratio. And add >> "start_writeback_ratio", and start writeback at >> start_writeback_ratio(default:90) * dirty_ratio / 100 [%]. >> In this way, specifying blocking ratio can be done in the same way >> as current kernel, but high/low watermark algorithm is enabled. >I like 3 better, it should make tuning behavior more precise. Then, what do you think of the following idea? (4) add `dirty_start_writeback_ratio' as percentage of memory, at which a generator of dirty pages itself starts writeback (that is, non-blocking ratio). In this way, `dirty_ratio' is used as the blocking ratio, so we don't need to modify the sysctl.conf etc. I think it's easier to understand for administrators of systems, because the interface is similar as `dirty_background_ratio' and`dirty_ratio.' If this is OK, I'll repost the patch. > You can make an argument for absolute values for writeback, > if my disk will only write 70MB/s I may only want 203 sec of > pending writes, regardless of available memory. To realize tuning with absolute values, I consider that we need to modify handling of `dirty_background_ratio,' `dirty_ratio' and so on as well as `dirty_start_writeback_ratio.' I think this should be done in another patch if this feature is required. Regards, -- Tomoki Sekiyama Hitachi, Ltd., Systems Development Laboratory