From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752650Ab3FDXXW (ORCPT ); Tue, 4 Jun 2013 19:23:22 -0400 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:51745 "EHLO LGEMRELSE6Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752365Ab3FDXXR (ORCPT ); Tue, 4 Jun 2013 19:23:17 -0400 X-AuditID: 9c930179-b7c1dae000003992-07-51ae76e31a0e Date: Wed, 5 Jun 2013 08:23:15 +0900 From: Minchan Kim To: Dave Hansen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mgorman@suse.de, tim.c.chen@linux.intel.com Subject: Re: [v5][PATCH 6/6] mm: vmscan: drain batch list during long operations Message-ID: <20130604232315.GA31006@blaptop> References: <20130603200202.7F5FDE07@viggo.jf.intel.com> <20130603200210.259954C3@viggo.jf.intel.com> <20130604060553.GF14719@blaptop> <51AE06B6.3030009@sr71.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51AE06B6.3030009@sr71.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Dave, On Tue, Jun 04, 2013 at 08:24:38AM -0700, Dave Hansen wrote: > On 06/03/2013 11:05 PM, Minchan Kim wrote: > >> > This ensures that we drain the batch if we are about to perform a > >> > pageout() or congestion_wait(), either of which will take some > >> > time. We expect this to help mitigate the worst of the latency > >> > increase that the batching could cause. > > Nice idea but I could see drain before pageout but congestion_wait? > > That comment managed to bitrot a bit :( > > The first version of these had the drain before pageout() only. Then, > Mel added a congestion_wait() call, and I modified the series to also > drain there. But, some other patches took the congestion_wait() back > out, so I took that drain back out. I am looking next-20130530 and it has still a congestion_wait. I'm confusing. :( if (PageWriteback(page)) { /* Case 1 above */ if (current_is_kswapd() && PageReclaim(page) && zone_is_reclaim_writeback(zone)) { congestion_wait(BLK_RW_ASYNC, HZ/10); zone_clear_flag(zone, ZONE_WRITEBACK); > > I _believe_ the only congestion_wait() left in there is a cgroup-related > one that we didn't think would cause very much harm. The congestion_wait I am seeing is not cgroup-related one. I'd like to clear this confusing. Thanks. > > -- > 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 -- Kind regards, Minchan Kim