From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753206AbXCRO4h (ORCPT ); Sun, 18 Mar 2007 10:56:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753226AbXCRO4g (ORCPT ); Sun, 18 Mar 2007 10:56:36 -0400 Received: from mail.tmr.com ([64.65.253.246]:42350 "EHLO gaimboi.tmr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753206AbXCRO4g (ORCPT ); Sun, 18 Mar 2007 10:56:36 -0400 Message-ID: <45FD53DB.5000207@tmr.com> Date: Sun, 18 Mar 2007 09:59:39 -0500 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.8) Gecko/20061105 SeaMonkey/1.0.6 MIME-Version: 1.0 To: Andrew Morton CC: Tomoki Sekiyama , 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> In-Reply-To: <20070315110745.af867b10.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: >> On Wed, 14 Mar 2007 21:42:46 +0900 Tomoki Sekiyama wrote: >> >> ... >> >> >> -Solution: >> >> I consider that all of the dirty pages for the disk have been written >> back and that the disk is clean if a process cannot write 'write_chunk' >> pages in balance_dirty_pages(). >> >> To avoid using up the free memory with dirty pages by passing blocking, >> this patchset adds a new threshold named vm.dirty_limit_ratio to sysctl. >> >> It modifies balance_dirty_pages() not to block when the amount of >> Dirty+Writeback is less than vm.dirty_limit_ratio percent of the memory. >> In the other cases, writers are throttled as current Linux does. >> >> >> In this patchset, vm.dirty_limit_ratio, instead of vm.dirty_ratio, is >> used as the clamping level of Dirty+Writeback. And, vm.dirty_ratio is >> used as the level at which a writers will itself start writeback of the >> dirty pages. > > Might be a reasonable solution - let's see what Peter comes up with too. > > Comments on the patch: > > - Please don't VM_DIRTY_LIMIT_RATIO: just use CTL_UNNUMBERED and leave > sysctl.h alone. > > - The 40% default is already too high. Let's set this new upper limit to > 40% and decrease he non-blocking ratio. > > - Please update the procfs documentation in ./Docmentation/ > > - I wonder if dirty_limit_ratio is the best name we could choose. > vm_dirty_blocking_ratio, perhaps? Dunno. > I don't like it, but I dislike it less than "dirty_limit_ratio" I guess. It would probably break things to change it now, including my sysctl.conf on a number of systems :-( -- Bill Davidsen "We have more to fear from the bungling of the incompetent than from the machinations of the wicked." - from Slashdot