From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91E21C43387 for ; Tue, 18 Dec 2018 13:52:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C31D21871 for ; Tue, 18 Dec 2018 13:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726824AbeLRNwG (ORCPT ); Tue, 18 Dec 2018 08:52:06 -0500 Received: from outbound-smtp26.blacknight.com ([81.17.249.194]:40628 "EHLO outbound-smtp26.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726626AbeLRNwB (ORCPT ); Tue, 18 Dec 2018 08:52:01 -0500 Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp26.blacknight.com (Postfix) with ESMTPS id 9A494B8829 for ; Tue, 18 Dec 2018 13:51:58 +0000 (GMT) Received: (qmail 7453 invoked from network); 18 Dec 2018 13:51:58 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.229.96]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 18 Dec 2018 13:51:58 -0000 Date: Tue, 18 Dec 2018 13:51:56 +0000 From: Mel Gorman To: Vlastimil Babka Cc: Linux-MM , David Rientjes , Andrea Arcangeli , Linus Torvalds , Michal Hocko , ying.huang@intel.com, kirill@shutemov.name, Andrew Morton , Linux List Kernel Mailing Subject: Re: [PATCH 09/14] mm, compaction: Ignore the fragmentation avoidance boost for isolation and compaction Message-ID: <20181218135156.GK29005@techsingularity.net> References: <20181214230310.572-1-mgorman@techsingularity.net> <20181214230310.572-10-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 18, 2018 at 01:36:42PM +0100, Vlastimil Babka wrote: > On 12/15/18 12:03 AM, Mel Gorman wrote: > > When pageblocks get fragmented, watermarks are artifically boosted to pages > > are reclaimed to avoid further fragmentation events. However, compaction > > is often either fragmentation-neutral or moving movable pages away from > > unmovable/reclaimable pages. As the actual watermarks are preserved, > > allow compaction to ignore the boost factor. > > Right, I should have realized that when reviewing the boost patch. I > think it would be useful to do the same change in > __compaction_suitable() as well. Compaction has its own "gap". > That gap is somewhat static though so I'm a bit more wary of it. However, the check in __isolate_free_page looks too agressive. We isolate in units of COMPACT_CLUSTER_MAX yet the watermark check there is based on the allocation request. That means for THP that we check if 512 pages can be allocated when only somewhere between 1 and 32 is needed for that compaction cycle to complete. Adjusting that might be more appropriate? -- Mel Gorman SUSE Labs