From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751825Ab3FDXgt (ORCPT ); Tue, 4 Jun 2013 19:36:49 -0400 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:54070 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750791Ab3FDXgq (ORCPT ); Tue, 4 Jun 2013 19:36:46 -0400 X-AuditID: 9c93016f-b7ba8ae000004f01-60-51ae7a0c95a5 Date: Wed, 5 Jun 2013 08:36:45 +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: <20130604233644.GC31006@blaptop> References: <20130603200202.7F5FDE07@viggo.jf.intel.com> <20130603200210.259954C3@viggo.jf.intel.com> <20130604060553.GF14719@blaptop> <51AE06B6.3030009@sr71.net> <20130604232315.GA31006@blaptop> <51AE78C3.1040500@sr71.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51AE78C3.1040500@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 On Tue, Jun 04, 2013 at 04:31:15PM -0700, Dave Hansen wrote: > On 06/04/2013 04:23 PM, Minchan Kim wrote: > > 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. > > Yeah, sorry for the confusion. There's been a whole lot of activity in > there. My set is also done on top of a couple of fixes that Mel posted > later on, including this one: > > https://patchwork.kernel.org/patch/2619901/ > > *That* one removes the congestion_wait() you noticed. Thanks for the information. My nitpick just gets disappeared. -- Kind regards, Minchan Kim