From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933753Ab0EUQAp (ORCPT ); Fri, 21 May 2010 12:00:45 -0400 Received: from cantor.suse.de ([195.135.220.2]:49378 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933711Ab0EUQAW (ORCPT ); Fri, 21 May 2010 12:00:22 -0400 Date: Fri, 21 May 2010 18:00:14 +0200 From: Jan Kara To: KOSAKI Motohiro Cc: Zan Lynx , lwoodman@redhat.com, LKML , linux-mm , Nick Piggin , Jan Kara Subject: Re: RFC: dirty_ratio back to 40% Message-ID: <20100521160014.GC3412@quack.suse.cz> References: <20100521083408.1E36.A69D9226@jp.fujitsu.com> <4BF5D875.3030900@acm.org> <20100521100943.1E4D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100521100943.1E4D.A69D9226@jp.fujitsu.com> 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 On Fri 21-05-10 10:11:59, KOSAKI Motohiro wrote: > > > So, I'd prefer to restore the default rather than both Redhat and SUSE apply exactly > > > same distro specific patch. because we can easily imazine other users will face the same > > > issue in the future. > > > > On desktop systems the low dirty limits help maintain interactive feel. > > Users expect applications that are saving data to be slow. They do not > > like it when every application in the system randomly comes to a halt > > because of one program stuffing data up to the dirty limit. > > really? > Do you mean our per-task dirty limit wouldn't works? > > If so, I think we need fix it. IOW sane per-task dirty limitation seems > independent issue from per-system dirty limit. Well, I don't know about any per-task dirty limits. What function implements them? Any application that dirties a single page can be caught and forced to call balance_dirty_pages() and do writeback. But generally what we observe on a desktop with lots of dirty memory is that application needs to allocate memory (either private one or for page cache) and that triggers direct reclaim so the allocation takes a long time to finish and thus the application is sluggish... Honza -- Jan Kara SUSE Labs, CR