From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta8.messagelabs.com (mail6.bemta8.messagelabs.com [216.82.243.55]) by kanga.kvack.org (Postfix) with ESMTP id 8C0F26B0170 for ; Wed, 31 Aug 2011 10:57:05 -0400 (EDT) Received: by gwaa20 with SMTP id a20so159748gwa.14 for ; Wed, 31 Aug 2011 07:56:59 -0700 (PDT) Date: Wed, 31 Aug 2011 23:56:51 +0900 From: Minchan Kim Subject: Re: [PATCH 3/3] compaction accouting fix Message-ID: <20110831145651.GA2198@barrios-desktop> References: <282a4531f23c5e35cfddf089f93559130b4bb660.1321112552.git.minchan.kim@gmail.com> <20110831113710.GC17512@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110831113710.GC17512@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , linux-mm , LKML , Mel Gorman , Rik van Riel On Wed, Aug 31, 2011 at 01:37:10PM +0200, Johannes Weiner wrote: > On Sun, Nov 13, 2011 at 01:37:43AM +0900, Minchan Kim wrote: > > I saw the following accouting of compaction during test of the series. > > > > compact_blocks_moved 251 > > compact_pages_moved 44 > > > > It's very awkward to me although it's possbile because it means we try to compact 251 blocks > > but it just migrated 44 pages. As further investigation, I found isolate_migratepages doesn't > > isolate any pages but it returns ISOLATE_SUCCESS and then, it just increases compact_blocks_moved > > but doesn't increased compact_pages_moved. > > > > This patch makes accouting of compaction works only in case of success of isolation. > > > > CC: Mel Gorman > > CC: Johannes Weiner > > CC: Rik van Riel > > Signed-off-by: Minchan Kim > > Acked-by: Johannes Weiner Thanks, Hannes. > > It's a teensy-bit awkward that isolate_migratepages() can return > success without actually isolating any new pages, just because there > are still some pages left from a previous run (cc->nr_migratepages is > maintained across isolation calls). If migrate_pages fails, we reset cc->nr_migratepages to zero in compact_zone. Am I missing something? > > Maybe isolate_migratepages() should just return an error if compaction > should really be aborted and 0 otherwise, and have compact_zone() > always check for cc->nr_migratepages itself? > > if (isolate_migratepages(zone, cc) < 0) { > ret = COMPACT_PARTIAL; > goto out; > } > > if (!cc->nr_migratepages) > continue; > > ... > > Just a nit-pick, though. If you don't agree, just leave it as is. -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org