Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932311AbcDLJDP (ORCPT ); Tue, 12 Apr 2016 05:03:15 -0400 Received: from mx2.suse.de ([195.135.220.15]:40543 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932109AbcDLJDN (ORCPT ); Tue, 12 Apr 2016 05:03:13 -0400 Subject: Re: mmotm woes, mainly compaction To: Hugh Dickins , Michal Hocko , Andrew Morton References: Cc: Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org From: Vlastimil Babka Message-ID: <570CB9CE.1070408@suse.cz> Date: Tue, 12 Apr 2016 11:03:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3147 Lines: 79 On 04/12/2016 09:18 AM, Hugh Dickins wrote: > 3. /proc/sys/vm/stat_refresh warns nr_isolated_anon and nr_isolated_file > go increasingly negative under compaction: which would add delay when > should be none, or no delay when should delay. putback_movable_pages() > decrements the NR_ISOLATED counts which acct_isolated() increments, > so isolate_migratepages_block() needs to acct before putback in that > special case, and isolate_migratepages_range() can always do the acct > itself, leaving migratepages putback to caller like most other places. The isolate_migratepages_block() part is mmotm-specific, so I'll split it out in this patch. Thanks for catching it and the lack of reset for cc->nr_migratepages which wasn't mentioned in changelog so I added it. > 5. It's easier to track the life of cc->migratepages if we don't assign > it to a migratelist variable. This is also included here. This is a -fix for: mm-compaction-skip-blocks-where-isolation-fails-in-async-direct-compaction.patch ----8<---- >From 59a0075b6cf85045aa2dc5cee1f27797bcd0b3d2 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Tue, 12 Apr 2016 10:51:20 +0200 Subject: [PATCH] mm, compaction: prevent nr_isolated_* from going negative /proc/sys/vm/stat_refresh warns nr_isolated_anon and nr_isolated_file go increasingly negative under compaction: which would add delay when should be none, or no delay when should delay. putback_movable_pages() decrements the NR_ISOLATED counts which acct_isolated() increments, so isolate_migratepages_block() needs to acct before putback in that special case. It's also useful to reset cc->nr_migratepages after putback so we don't needlessly return too early on the COMPACT_CLUSTER_MAX check. Also it's easier to track the life of cc->migratepages if we don't assign it to a migratelist variable. --- mm/compaction.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 67f886ecd773..ab649fba3d88 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -638,7 +638,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, { struct zone *zone = cc->zone; unsigned long nr_scanned = 0, nr_isolated = 0; - struct list_head *migratelist = &cc->migratepages; struct lruvec *lruvec; unsigned long flags = 0; bool locked = false; @@ -817,7 +816,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, del_page_from_lru_list(page, lruvec, page_lru(page)); isolate_success: - list_add(&page->lru, migratelist); + list_add(&page->lru, &cc->migratepages); cc->nr_migratepages++; nr_isolated++; @@ -851,9 +850,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, spin_unlock_irqrestore(&zone->lru_lock, flags); locked = false; } - putback_movable_pages(migratelist); - nr_isolated = 0; + acct_isolated(zone, cc); + putback_movable_pages(&cc->migratepages); + cc->nr_migratepages = 0; cc->last_migrated_pfn = 0; + nr_isolated = 0; } if (low_pfn < next_skip_pfn) { -- 2.8.1