From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753965AbcGLRY5 (ORCPT ); Tue, 12 Jul 2016 13:24:57 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:51892 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751014AbcGLRY4 (ORCPT ); Tue, 12 Jul 2016 13:24:56 -0400 Date: Tue, 12 Jul 2016 13:24:46 -0400 From: Johannes Weiner To: Mel Gorman Cc: Andrew Morton , Linux-MM , Rik van Riel , Vlastimil Babka , Minchan Kim , Joonsoo Kim , LKML Subject: Re: [PATCH 22/34] mm, page_alloc: wake kswapd based on the highest eligible zone Message-ID: <20160712172446.GB7307@cmpxchg.org> References: <1467970510-21195-1-git-send-email-mgorman@techsingularity.net> <1467970510-21195-23-git-send-email-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1467970510-21195-23-git-send-email-mgorman@techsingularity.net> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 08, 2016 at 10:34:58AM +0100, Mel Gorman wrote: > The ac_classzone_idx is used as the basis for waking kswapd and that is based > on the preferred zoneref. If the preferred zoneref's first zone is lower > than what is available on other nodes, it's possible that kswapd is woken > on a zone with only higher, but still eligible, zones. As classzone_idx > is strictly adhered to now, it causes a problem because eligible pages > are skipped. > > For example, node 0 has only DMA32 and node 1 has only NORMAL. An allocating > context running on node 0 may wake kswapd on node 1 telling it to skip > all NORMAL pages. > > Signed-off-by: Mel Gorman > Acked-by: Hillf Danton Acked-by: Johannes Weiner