From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756825Ab0HANDg (ORCPT ); Sun, 1 Aug 2010 09:03:36 -0400 Received: from mga02.intel.com ([134.134.136.20]:16975 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754333Ab0HANDe (ORCPT ); Sun, 1 Aug 2010 09:03:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.55,298,1278313200"; d="scan'208";a="643700253" Date: Sun, 1 Aug 2010 21:03:01 +0800 From: Wu Fengguang To: Andrew Morton Cc: Mel Gorman , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel , Johannes Weiner , Jens Axboe , Christoph Hellwig , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Andrea Arcangeli , pvz@pvz.pp.se, bgamari@gmail.com, larppaxyz@gmail.com, seanj@xyke.com, kernel-bugs.dev1world@spamgourmet.com, akatopaz@gmail.com, frankrq2009@gmx.com, thomas.pi@arcor.de, spawels13@gmail.com, vshader@gmail.com, rockorequin@hotmail.com, ylalym@gmail.com, theholyettlz@googlemail.com, hassium@yandex.ru Subject: Re: [PATCH 6/6] vmscan: Kick flusher threads to clean pages when reclaim is encountering dirty pages Message-ID: <20100801130300.GA19523@localhost> References: <1280497020-22816-1-git-send-email-mel@csn.ul.ie> <1280497020-22816-7-git-send-email-mel@csn.ul.ie> <20100730150601.199c5618.akpm@linux-foundation.org> <20100801115640.GA18943@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100801115640.GA18943@localhost> 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 Sun, Aug 01, 2010 at 07:56:40PM +0800, Wu Fengguang wrote: > > Sigh. We have sooo many problems with writeback and latency. Read > > https://bugzilla.kernel.org/show_bug.cgi?id=12309 and weep. Everyone's > > running away from the issue and here we are adding code to solve some > > alleged stack-overflow problem which seems to be largely a non-problem, > > by making changes which may worsen our real problems. > > I'm sweeping bug 12309. Most people reports some data writes, though > relative few explicitly stated memory pressure is another necessary > condition. #14: Per von Zweigbergk Ubuntu 2.6.27 slowdown when copying 25MB/s USB stick to 10 MB/s SSD. KOSAKI and my patches won't fix 2.6.27, since it only do congestion_wait() and wait_on_page_writeback() for order>3 allocations. There may be more bugs there. #24: Per von Zweigbergk The encryption of the SSD very significantly increases the problem. This is expected. Data encryption roughly doubles page consumption speed (there may be temp buffers allocated/dropped quickly), hence vmscan pressure. #26: Per von Zweigbergk Disabling swap makes the terminal launch much faster while copying; However Firefox and vim hang much more aggressively and frequently during copying. It's interesting to see processes behave differently. Is this reproducible at all? #34: Ben Gamari There is evidence that x86-64 is a factor here. Because x86-64 does order-1 page allocation in fork() and consumes more memory (larger user space code/data)? #36: Lari Temmes Go from usable to totally unusable when switching from a SMP kernel to a UP kernel on a single CPU laptop He should be testing 2.6.28. I'm not aware of known bugs there. #47: xyke Renicing pdflush -10 had some great improvement on basic responsiveness. It sure helps :) Too much (old) messages there. I'm hoping some of the still active bug reporters to test the following patches (they are for the -mmotm tree, need to unindent code for Linus's tree) and see if there are any improvements. http://lkml.org/lkml/2010/8/1/40 http://lkml.org/lkml/2010/8/1/45 Thanks, Fengguang