From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f200.google.com (mail-lb0-f200.google.com [209.85.217.200]) by kanga.kvack.org (Postfix) with ESMTP id 059D26B0005 for ; Fri, 17 Jun 2016 06:46:09 -0400 (EDT) Received: by mail-lb0-f200.google.com with SMTP id na2so38776451lbb.1 for ; Fri, 17 Jun 2016 03:46:08 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id ec11si11305545wjb.99.2016.06.17.03.46.07 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 17 Jun 2016 03:46:07 -0700 (PDT) Subject: Re: [PATCH 21/27] mm, vmscan: Only wakeup kswapd once per node for the requested classzone References: <1465495483-11855-1-git-send-email-mgorman@techsingularity.net> <1465495483-11855-22-git-send-email-mgorman@techsingularity.net> From: Vlastimil Babka Message-ID: <2ce07fcf-7b7d-a70b-ed7b-60867ad4458f@suse.cz> Date: Fri, 17 Jun 2016 12:46:05 +0200 MIME-Version: 1.0 In-Reply-To: <1465495483-11855-22-git-send-email-mgorman@techsingularity.net> Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Andrew Morton , Linux-MM Cc: Rik van Riel , Johannes Weiner , LKML On 06/09/2016 08:04 PM, Mel Gorman wrote: > kswapd is woken when zones are below the low watermark but the wakeup > decision is not taking the classzone into account. Now that reclaim is > node-based, it is only required to wake kswapd once per node and only if > all zones are unbalanced for the requested classzone. > > Note that one node might be checked multiple times but there is no cheap > way of tracking what nodes have already been visited for zoneslists that > be ordered by either zone or node. Wouldn't it be possible to optimize for node order as you did in direct reclaim? Do the zone_balanced checks when going through zonelist, and once node changes in iteration, wake up if no eligible zones visited so far were balanced. > Signed-off-by: Mel Gorman > --- > mm/vmscan.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7a2d69612231..b9cff9047ac0 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3389,6 +3389,7 @@ static int kswapd(void *p) > void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) > { > pg_data_t *pgdat; > + int z; > > if (!populated_zone(zone)) > return; > @@ -3402,8 +3403,16 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) > pgdat->kswapd_order = max(pgdat->kswapd_order, order); > if (!waitqueue_active(&pgdat->kswapd_wait)) > return; > - if (zone_balanced(zone, order, 0)) > - return; > + > + /* Only wake kswapd if all zones are unbalanced */ > + for (z = 0; z <= classzone_idx; z++) { > + zone = pgdat->node_zones + z; > + if (!populated_zone(zone)) > + continue; > + > + if (zone_balanced(zone, order, classzone_idx)) > + return; > + } > > trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); > wake_up_interruptible(&pgdat->kswapd_wait); > -- 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