From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 0C98B6B01C6 for ; Tue, 15 Jun 2010 22:24:53 -0400 (EDT) Received: from m1.gw.fujitsu.co.jp ([10.0.50.71]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o5G2OoQN029118 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Wed, 16 Jun 2010 11:24:50 +0900 Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 5E38045DE53 for ; Wed, 16 Jun 2010 11:24:50 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 1EBF045DE52 for ; Wed, 16 Jun 2010 11:24:50 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id EAECEE08005 for ; Wed, 16 Jun 2010 11:24:49 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 8F44BE18003 for ; Wed, 16 Jun 2010 11:24:49 +0900 (JST) Date: Wed, 16 Jun 2010 11:20:24 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 12/12] vmscan: Do not writeback pages in direct reclaim Message-Id: <20100616112024.5b093905.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100616104036.b45d352b.kamezawa.hiroyu@jp.fujitsu.com> References: <1276514273-27693-1-git-send-email-mel@csn.ul.ie> <1276514273-27693-13-git-send-email-mel@csn.ul.ie> <4C16A567.4080000@redhat.com> <20100615114510.GE26788@csn.ul.ie> <4C17815A.8080402@redhat.com> <20100615135928.GK26788@csn.ul.ie> <4C178868.2010002@redhat.com> <20100615141601.GL26788@csn.ul.ie> <20100616091755.7121c7d3.kamezawa.hiroyu@jp.fujitsu.com> <4C181AFD.5060503@redhat.com> <20100616093958.00673123.kamezawa.hiroyu@jp.fujitsu.com> <4C182097.2070603@redhat.com> <20100616104036.b45d352b.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Rik van Riel , Mel Gorman , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Johannes Weiner , Christoph Hellwig , Andrew Morton List-ID: On Wed, 16 Jun 2010 10:40:36 +0900 KAMEZAWA Hiroyuki wrote: > On Tue, 15 Jun 2010 20:53:43 -0400 > Rik van Riel wrote: > > > On 06/15/2010 08:39 PM, KAMEZAWA Hiroyuki wrote: > > > > > Hmm, or do you recommend no-dirty-page-writeback when a memcg hits limit ? > > > Maybe we'll see much swaps. > > > > > > I want to go with this for a while, changing memcg's behavior will took > > > some amounts of time, there are only a few developpers. > > > > One thing we can do, for kswapd, memcg and direct reclaim alike, > > is to tell the flusher threads to flush pages related to a pageout > > candidate page to disk. > > > > That way the reclaiming processes can wait on some disk IO to > > finish, while the flusher thread takes care of the actual flushing. > > > > That should also fix the "kswapd filesystem IO has really poor IO > > patterns" issue. > > > > There's no reason not to fix this issue the right way. > > > yes. but this patch just stops writeback. I think it's sane to ask > not to change behavior until there are some useful changes in flusher > threads. > > IMO, until flusher threads can work with I/O cgroup, memcg shoudln't > depend on it because writeback allows stealing resource without it. > BTW, copy_from_user/copy_to_user is _real_ problem, I'm afraid following much more than memcg. handle_mm_fault() -> handle_pte_fault() -> do_wp_page() -> balance_dirty_page_rate_limited() -> balance_dirty_pages() -> writeback_inodes_wbc() -> writeback_inodes_wb() -> writeback_sb_inodes() -> writeback_single_inode() -> do_writepages() -> generic_write_pages() -> write_cache_pages() // use on-stack pagevec. -> writepage() maybe much more stack consuming than memcg->writeback after vmscan.c diet. Bye. -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org