Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754587Ab3DKKBU (ORCPT ); Thu, 11 Apr 2013 06:01:20 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40194 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753885Ab3DKKBT (ORCPT ); Thu, 11 Apr 2013 06:01:19 -0400 Date: Thu, 11 Apr 2013 11:01:15 +0100 From: Mel Gorman To: Joonsoo Kim Cc: Linux-MM , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , LKML Subject: Re: [PATCH 08/10] mm: vmscan: Have kswapd shrink slab only once per priority Message-ID: <20130411100115.GJ3710@suse.de> References: <1363525456-10448-1-git-send-email-mgorman@suse.de> <1363525456-10448-9-git-send-email-mgorman@suse.de> <20130409065325.GA4411@lge.com> <20130409111358.GB2002@suse.de> <20130410052142.GB5872@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20130410052142.GB5872@lge.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: 1958 Lines: 46 On Wed, Apr 10, 2013 at 02:21:42PM +0900, Joonsoo Kim wrote: > > > > @@ -2673,9 +2674,15 @@ static bool kswapd_shrink_zone(struct zone *zone, > > > > sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); > > > > shrink_zone(zone, sc); > > > > > > > > - reclaim_state->reclaimed_slab = 0; > > > > - nr_slab = shrink_slab(&shrink, sc->nr_scanned, lru_pages); > > > > - sc->nr_reclaimed += reclaim_state->reclaimed_slab; > > > > + /* > > > > + * Slabs are shrunk for each zone once per priority or if the zone > > > > + * being balanced is otherwise unreclaimable > > > > + */ > > > > + if (shrinking_slab || !zone_reclaimable(zone)) { > > > > + reclaim_state->reclaimed_slab = 0; > > > > + nr_slab = shrink_slab(&shrink, sc->nr_scanned, lru_pages); > > > > + sc->nr_reclaimed += reclaim_state->reclaimed_slab; > > > > + } > > > > > > > > if (nr_slab == 0 && !zone_reclaimable(zone)) > > > > zone->all_unreclaimable = 1; > > > > > > Why shrink_slab() is called here? > > > > Preserves existing behaviour. > > Yes, but, with this patch, existing behaviour is changed, that is, we call > shrink_slab() once per priority. For now, there is no reason this function > is called here. How about separating it and executing it outside of > zone loop? > We are calling it fewer times but it's still receiving the same information from sc->nr_scanned it received before. With the change you are suggesting it would be necessary to accumulating sc->nr_scanned for each zone shrunk and then pass the sum to shrink_slab() once per priority. While this is not necessarily wrong, there is little or no motivation to alter the shrinkers in this manner in this series. -- 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/