Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757947Ab1FIODL (ORCPT ); Thu, 9 Jun 2011 10:03:11 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41604 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757290Ab1FIODJ (ORCPT ); Thu, 9 Jun 2011 10:03:09 -0400 Date: Thu, 9 Jun 2011 15:03:05 +0100 From: Mel Gorman To: Minchan Kim Cc: Andrew Morton , linux-mm , LKML , KOSAKI Motohiro , Andrea Arcangeli , Rik van Riel , Johannes Weiner , KAMEZAWA Hiroyuki Subject: Re: [PATCH v3 04/10] compaction: make isolate_lru_page with filter aware Message-ID: <20110609140305.GW5247@suse.de> References: <10ad16e14fdbe47ac36f7e55ae72ed59ae73ed0c.1307455422.git.minchan.kim@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <10ad16e14fdbe47ac36f7e55ae72ed59ae73ed0c.1307455422.git.minchan.kim@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2509 Lines: 65 On Tue, Jun 07, 2011 at 11:38:17PM +0900, Minchan Kim wrote: > In async mode, compaction doesn't migrate dirty or writeback pages. > So, it's meaningless to pick the page and re-add it to lru list. > > Of course, when we isolate the page in compaction, the page might > be dirty or writeback but when we try to migrate the page, the page > would be not dirty, writeback. So it could be migrated. But it's > very unlikely as isolate and migration cycle is much faster than > writeout. > > So, this patch helps cpu and prevent unnecessary LRU churning. > > Cc: Andrea Arcangeli > Reviewed-by: KAMEZAWA Hiroyuki > Reviewed-by: KOSAKI Motohiro > Acked-by: Johannes Weiner > Acked-by: Mel Gorman > Acked-by: Rik van Riel > Signed-off-by: Minchan Kim > --- > mm/compaction.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index f0d75e9..8079346 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -243,6 +243,7 @@ static unsigned long isolate_migratepages(struct zone *zone, > unsigned long last_pageblock_nr = 0, pageblock_nr; > unsigned long nr_scanned = 0, nr_isolated = 0; > struct list_head *migratelist = &cc->migratepages; > + enum ISOLATE_MODE mode = ISOLATE_ACTIVE|ISOLATE_INACTIVE; > > /* Do not scan outside zone boundaries */ > low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn); > @@ -326,9 +327,11 @@ static unsigned long isolate_migratepages(struct zone *zone, > continue; > } > > + if (!cc->sync) > + mode |= ISOLATE_CLEAN; > + > /* Try isolate the page */ > - if (__isolate_lru_page(page, > - ISOLATE_ACTIVE|ISOLATE_INACTIVE, 0) != 0) > + if (__isolate_lru_page(page, mode, 0) != 0) > continue; > > VM_BUG_ON(PageTransCompound(page)); Looks good for compaction! This change makes a lot of sense. However I would expand the meaning of this patch. Introduce ISOLATE_CLEAN in this patch and update both compaction and __zone_reclaim. You might encounter some mess mapping RECLAIM_WRITE to ISOLATE_CLEAN but nothing unmanageable. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/