From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f197.google.com (mail-qt0-f197.google.com [209.85.216.197]) by kanga.kvack.org (Postfix) with ESMTP id 2FEA16B0069 for ; Wed, 19 Oct 2016 06:36:19 -0400 (EDT) Received: by mail-qt0-f197.google.com with SMTP id z54so17438108qtz.0 for ; Wed, 19 Oct 2016 03:36:19 -0700 (PDT) Received: from mail-qk0-f193.google.com (mail-qk0-f193.google.com. [209.85.220.193]) by mx.google.com with ESMTPS id o71si20878256qka.310.2016.10.19.03.36.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Oct 2016 03:36:18 -0700 (PDT) Received: by mail-qk0-f193.google.com with SMTP id f128so1483588qkb.0 for ; Wed, 19 Oct 2016 03:36:18 -0700 (PDT) Date: Wed, 19 Oct 2016 12:36:16 +0200 From: Michal Hocko Subject: Re: [PATCH] mm, compaction: fix NR_ISOLATED_* stats for pfn based migration Message-ID: <20161019103616.GG7517@dhcp22.suse.cz> References: <20161019080240.9682-1-mhocko@kernel.org> <2e4d79f9-74e5-5085-4037-caa9c1cb43e4@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2e4d79f9-74e5-5085-4037-caa9c1cb43e4@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , "ming.ling" , Minchan Kim , Mel Gorman , Joonsoo Kim , linux-mm@kvack.org, LKML On Wed 19-10-16 11:39:36, Vlastimil Babka wrote: > On 10/19/2016 10:02 AM, Michal Hocko wrote: > > From: Ming Ling > > > > Since bda807d44454 ("mm: migrate: support non-lru movable page > > migration") isolate_migratepages_block) can isolate !PageLRU pages which > > would acct_isolated account as NR_ISOLATED_*. Accounting these non-lru > > pages NR_ISOLATED_{ANON,FILE} doesn't make any sense and it can misguide > > heuristics based on those counters such as pgdat_reclaimable_pages resp. > > too_many_isolated which would lead to unexpected stalls during the > > direct reclaim without any good reason. Note that > > __alloc_contig_migrate_range can isolate a lot of pages at once. > > > > On mobile devices such as 512M ram android Phone, it may use a big zram > > swap. In some cases zram(zsmalloc) uses too many non-lru but migratedable > > pages, such as: > > > > MemTotal: 468148 kB > > Normal free:5620kB > > Free swap:4736kB > > Total swap:409596kB > > ZRAM: 164616kB(zsmalloc non-lru pages) > > active_anon:60700kB > > inactive_anon:60744kB > > active_file:34420kB > > inactive_file:37532kB > > > > Fix this by only accounting lru pages to NR_ISOLATED_* in > > isolate_migratepages_block right after they were isolated and we still > > know they were on LRU. Drop acct_isolated because it is called after the > > fact and we've lost that information. Batching per-cpu counter doesn't > > make much improvement anyway. Also make sure that we uncharge only LRU > > pages when putting them back on the LRU in putback_movable_pages resp. > > when unmap_and_move migrates the page. > > [mhocko@suse.com: replace acct_isolated() with direct counting] > ? Why not. I just considered this patch more as a rework of the original than an incremental fix. But whatever... > Indeed much better than before. IIRC I've personally introduced one or two > bugs involving acct_isolated() (lack of) usage :) Thanks. Yeah, it was subtle as hell. > > Fixes: bda807d44454 ("mm: migrate: support non-lru movable page migration") > > Acked-by: Minchan Kim > > Signed-off-by: Ming Ling > > Signed-off-by: Michal Hocko > > Acked-by: Vlastimil Babka Thanks! -- Michal Hocko SUSE Labs -- 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