From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852Ab1KUNJe (ORCPT ); Mon, 21 Nov 2011 08:09:34 -0500 Received: from cantor2.suse.de ([195.135.220.15]:45521 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752718Ab1KUNJV (ORCPT ); Mon, 21 Nov 2011 08:09:21 -0500 Date: Mon, 21 Nov 2011 13:09:15 +0000 From: Mel Gorman To: Andrea Arcangeli Cc: linux-mm@kvack.org, Minchan Kim , Jan Kara , Andy Isaacson , Rik van Riel , Johannes Weiner , linux-kernel@vger.kernel.org Subject: Re: [PATCH 7/8] Revert "vmscan: abort reclaim/compaction if compaction can proceed" Message-ID: <20111121130915.GF19415@suse.de> References: <1321635524-8586-1-git-send-email-mgorman@suse.de> <1321732460-14155-8-git-send-email-aarcange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1321732460-14155-8-git-send-email-aarcange@redhat.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 On Sat, Nov 19, 2011 at 08:54:19PM +0100, Andrea Arcangeli wrote: > This reverts commit e0c23279c9f800c403f37511484d9014ac83adec. > > If reclaim runs with an high order allocation, it means compaction > failed. That means something went wrong with compaction so we can't > stop reclaim too. We can't assume it failed and was deferred because > of the too low watermarks in compaction_suitable only, it may have > failed for other reasons. > When Rik was testing with THP enabled, he found that there was way too much memory free on his machine. The problem was that THP caused reclaim to be too aggressive and that's what led to that pair of patches. While I do not think it was confirmed, the expectation was that the performance of workloads whose working set size was close to total physical RAM and mostly filesystem-backed files would suffer if THP was enabled. In other words, reverting these patches needs to be a last resort. -- Mel Gorman SUSE Labs