From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 878C56B0069 for ; Thu, 20 Oct 2016 23:16:10 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id h24so41839516pfh.0 for ; Thu, 20 Oct 2016 20:16:10 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id e23si502111pga.305.2016.10.20.20.16.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 20 Oct 2016 20:16:09 -0700 (PDT) Date: Thu, 20 Oct 2016 20:16:06 -0700 From: Andrew Morton Subject: Re: [PATCH] mm, compaction: fix NR_ISOLATED_* stats for pfn based migration Message-Id: <20161020201606.2da29e792856a03a0da0adb2@linux-foundation.org> In-Reply-To: <20161019080240.9682-1-mhocko@kernel.org> References: <20161019080240.9682-1-mhocko@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: "ming.ling" , Minchan Kim , Mel Gorman , Vlastimil Babka , Joonsoo Kim , linux-mm@kvack.org, LKML , Michal Hocko On Wed, 19 Oct 2016 10:02:40 +0200 Michal Hocko wrote: > 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. It isn't worth backporting into 4.8.x? -- 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