Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933620Ab3CUPsM (ORCPT ); Thu, 21 Mar 2013 11:48:12 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38554 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753703Ab3CUPsL (ORCPT ); Thu, 21 Mar 2013 11:48:11 -0400 Date: Thu, 21 Mar 2013 16:48:10 +0100 From: Michal Hocko To: Mel Gorman Cc: Linux-MM , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , LKML Subject: Re: [PATCH 05/10] mm: vmscan: Do not allow kswapd to scan at maximum priority Message-ID: <20130321154810.GR6094@dhcp22.suse.cz> References: <1363525456-10448-1-git-send-email-mgorman@suse.de> <1363525456-10448-6-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1363525456-10448-6-git-send-email-mgorman@suse.de> 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: 1654 Lines: 49 On Sun 17-03-13 13:04:11, Mel Gorman wrote: > Page reclaim at priority 0 will scan the entire LRU as priority 0 is > considered to be a near OOM condition. Kswapd can reach priority 0 quite > easily if it is encountering a large number of pages it cannot reclaim > such as pages under writeback. When this happens, kswapd reclaims very > aggressively even though there may be no real risk of allocation failure > or OOM. > > This patch prevents kswapd reaching priority 0 and trying to reclaim > the world. Direct reclaimers will still reach priority 0 in the event > of an OOM situation. OK, it should work. raise_priority should prevent from pointless lowerinng the priority and if there is really nothing to reclaim then relying on the direct reclaim is probably a better idea. > Signed-off-by: Mel Gorman Reviewed-by: Michal Hocko > --- > mm/vmscan.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7513bd1..af3bb6f 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2891,7 +2891,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, > */ > if (raise_priority || !this_reclaimed) > sc.priority--; > - } while (sc.priority >= 0 && > + } while (sc.priority >= 1 && > !pgdat_balanced(pgdat, order, *classzone_idx)); > > out: > -- > 1.8.1.4 > -- Michal Hocko 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/