From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx152.postini.com [74.125.245.152]) by kanga.kvack.org (Postfix) with SMTP id CECC66B0002 for ; Thu, 21 Mar 2013 08:59:41 -0400 (EDT) Date: Thu, 21 Mar 2013 13:59:39 +0100 From: Michal Hocko Subject: Re: [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims at each priority Message-ID: <20130321125939.GK6094@dhcp22.suse.cz> References: <1363525456-10448-1-git-send-email-mgorman@suse.de> <1363525456-10448-2-git-send-email-mgorman@suse.de> <20130320161847.GD27375@dhcp22.suse.cz> <20130321094713.GD1878@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130321094713.GD1878@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Linux-MM , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , LKML On Thu 21-03-13 09:47:13, Mel Gorman wrote: > On Wed, Mar 20, 2013 at 05:18:47PM +0100, Michal Hocko wrote: > > On Sun 17-03-13 13:04:07, Mel Gorman wrote: > > [...] > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > > index 88c5fed..4835a7a 100644 > > > --- a/mm/vmscan.c > > > +++ b/mm/vmscan.c > > > @@ -2593,6 +2593,32 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, > > > } > > > > > > /* > > > + * kswapd shrinks the zone by the number of pages required to reach > > > + * the high watermark. > > > + */ > > > +static void kswapd_shrink_zone(struct zone *zone, > > > + struct scan_control *sc, > > > + unsigned long lru_pages) > > > +{ > > > + unsigned long nr_slab; > > > + struct reclaim_state *reclaim_state = current->reclaim_state; > > > + struct shrink_control shrink = { > > > + .gfp_mask = sc->gfp_mask, > > > + }; > > > + > > > + /* Reclaim above the high watermark. */ > > > + sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); > > > > OK, so the cap is at high watermark which sounds OK to me, although I > > would expect balance_gap being considered here. Is it not used > > intentionally or you just wanted to have a reasonable upper bound? > > > > It's intentional. The balance_gap is taken into account before the > decision to shrink but not afterwards. As the watermark check after > shrinking is based on just the high watermark, I decided to have > shrink_zone reclaim on that basis. OK, it makes sense. Thanks both you and Rik for clarification. -- Michal Hocko SUSE Labs -- 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