Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758568AbcJQIm6 (ORCPT ); Mon, 17 Oct 2016 04:42:58 -0400 Received: from mail-lf0-f67.google.com ([209.85.215.67]:34117 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758268AbcJQIms (ORCPT ); Mon, 17 Oct 2016 04:42:48 -0400 Date: Mon, 17 Oct 2016 10:42:45 +0200 From: Michal Hocko To: Minchan Kim Cc: Ming Ling , akpm@linux-foundation.org, mgorman@techsingularity.net, vbabka@suse.cz, hannes@cmpxchg.org, baiyaowei@cmss.chinamobile.com, iamjoonsoo.kim@lge.com, rientjes@google.com, hughd@google.com, kirill.shutemov@linux.intel.com, riel@redhat.com, mgorman@suse.de, aquini@redhat.com, corbet@lwn.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org, orson.zhai@spreadtrum.com, geng.ren@spreadtrum.com, chunyan.zhang@spreadtrum.com, zhizhou.tian@spreadtrum.com, yuming.han@spreadtrum.com, xiajing@spreadst.com Subject: Re: [PATCH v2] mm: exclude isolated non-lru pages from NR_ISOLATED_ANON or NR_ISOLATED_FILE. Message-ID: <20161017084244.GF23322@dhcp22.suse.cz> References: <20161013080936.GG21678@dhcp22.suse.cz> <20161014083219.GA20260@spreadtrum.com> <20161014113044.GB6063@dhcp22.suse.cz> <20161014134604.GA2179@blaptop> <20161014135334.GF6063@dhcp22.suse.cz> <20161014144448.GA2899@blaptop> <20161014150355.GH6063@dhcp22.suse.cz> <20161014152633.GA3157@blaptop> <20161015071044.GC9949@dhcp22.suse.cz> <20161016230618.GB9196@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161016230618.GB9196@bbox> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8681 Lines: 235 On Mon 17-10-16 08:06:18, Minchan Kim wrote: > Hi Michal, > > On Sat, Oct 15, 2016 at 09:10:45AM +0200, Michal Hocko wrote: > > On Sat 15-10-16 00:26:33, Minchan Kim wrote: > > > On Fri, Oct 14, 2016 at 05:03:55PM +0200, Michal Hocko wrote: > > [...] > > > > diff --git a/mm/compaction.c b/mm/compaction.c > > > > index 0409a4ad6ea1..6584705a46f6 100644 > > > > --- a/mm/compaction.c > > > > +++ b/mm/compaction.c > > > > @@ -685,7 +685,8 @@ static bool too_many_isolated(struct zone *zone) > > > > */ > > > > static unsigned long > > > > isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > > > > - unsigned long end_pfn, isolate_mode_t isolate_mode) > > > > + unsigned long end_pfn, isolate_mode_t isolate_mode, > > > > + unsigned long *isolated_file, unsigned long *isolated_anon) > > > > { > > > > struct zone *zone = cc->zone; > > > > unsigned long nr_scanned = 0, nr_isolated = 0; > > > > @@ -866,6 +867,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > > > > > > > > /* Successfully isolated */ > > > > del_page_from_lru_list(page, lruvec, page_lru(page)); > > > > + if (page_is_file_cache(page)) > > > > + (*isolated_file)++; > > > > + else > > > > + (*isolated_anon)++; > > > > > > > > isolate_success: > > > > list_add(&page->lru, &cc->migratepages); > > > > > > > > Makes more sense? > > > > > > It is doable for isolation part. IOW, maybe we can make acct_isolated > > > simple with those counters but we need to handle migrate, putback part. > > > If you want to remove the check of __PageMoable with those counter, it > > > means we should pass the counter on every functions related migration > > > where isolate, migrate, putback parts. > > > > OK, I see. Can we just get rid of acct_isolated altogether? Why cannot > > we simply update NR_ISOLATED_* while isolating pages? Just looking at > > isolate_migratepages_block: > > acct_isolated(zone, cc); > > putback_movable_pages(&cc->migratepages); > > > > suggests we are doing something suboptimal. I guess we cannot get rid of > > __PageMoveble checks which is sad because that just adds a lot of > > confusion because checking for !__PageMovable(page) for LRU pages is > > just a head scratcher (LRU pages are movable arent' they?). Maybe it > > would be even good to get rid of this misnomer. PageNonLRUMovable? > > Yeah, I hated the naming but didn't have a good idea. > PageNonLRUMovable, definitely, one I thought as candidate but dropped > by lenghthy naming. If others don't object, I am happy to change it. Yes it is long but it is less confusing because it is just utterly confusing to test for LRU pages with !__PageMovable when in fact they are movable. Heck even unreclaimable pages are movable unless explicitly configured to not be. > > Anyway, I would suggest to do something like this. Batching NR_ISOLATED* > > just doesn't make all that much sense as these are per-cpu and the > > resulting code seems to be easier without it. > > Agree. Could you resend it as formal patch? Sure, what do you think about the following? I haven't marked it for stable because there was no bug report for it AFAIU. --- >From 3b2bd4486f36ada9f6dc86d3946855281455ba9f Mon Sep 17 00:00:00 2001 From: Ming Ling Date: Mon, 17 Oct 2016 10:26:50 +0200 Subject: [PATCH] mm, compaction: fix NR_ISOLATED_* stats for pfn based migration 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. Fixes: bda807d44454 ("mm: migrate: support non-lru movable page migration") Signed-off-by: Ming Ling Signed-off-by: Michal Hocko --- mm/compaction.c | 25 +++---------------------- mm/migrate.c | 15 +++++++++++---- 2 files changed, 14 insertions(+), 26 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 0409a4ad6ea1..df1fd0c20e5c 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -634,22 +634,6 @@ isolate_freepages_range(struct compact_control *cc, return pfn; } -/* Update the number of anon and file isolated pages in the zone */ -static void acct_isolated(struct zone *zone, struct compact_control *cc) -{ - struct page *page; - unsigned int count[2] = { 0, }; - - if (list_empty(&cc->migratepages)) - return; - - list_for_each_entry(page, &cc->migratepages, lru) - count[!!page_is_file_cache(page)]++; - - mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON, count[0]); - mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, count[1]); -} - /* Similar to reclaim, but different enough that they don't share logic */ static bool too_many_isolated(struct zone *zone) { @@ -866,6 +850,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, /* Successfully isolated */ del_page_from_lru_list(page, lruvec, page_lru(page)); + inc_node_page_state(zone->zone_pgdat, + NR_ISOLATED_ANON + page_is_file_cache(page)); isolate_success: list_add(&page->lru, &cc->migratepages); @@ -902,7 +888,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, spin_unlock_irqrestore(zone_lru_lock(zone), flags); locked = false; } - acct_isolated(zone, cc); putback_movable_pages(&cc->migratepages); cc->nr_migratepages = 0; cc->last_migrated_pfn = 0; @@ -988,7 +973,6 @@ isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn, if (cc->nr_migratepages == COMPACT_CLUSTER_MAX) break; } - acct_isolated(cc->zone, cc); return pfn; } @@ -1258,10 +1242,8 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, low_pfn = isolate_migratepages_block(cc, low_pfn, block_end_pfn, isolate_mode); - if (!low_pfn || cc->contended) { - acct_isolated(zone, cc); + if (!low_pfn || cc->contended) return ISOLATE_ABORT; - } /* * Either we isolated something and proceed with migration. Or @@ -1271,7 +1253,6 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, break; } - acct_isolated(zone, cc); /* Record where migration scanner will be restarted. */ cc->migrate_pfn = low_pfn; diff --git a/mm/migrate.c b/mm/migrate.c index 99250aee1ac1..66ce6b490b13 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -168,8 +168,6 @@ void putback_movable_pages(struct list_head *l) continue; } list_del(&page->lru); - dec_node_page_state(page, NR_ISOLATED_ANON + - page_is_file_cache(page)); /* * We isolated non-lru movable page so here we can use * __PageMovable because LRU page's mapping cannot have @@ -186,6 +184,8 @@ void putback_movable_pages(struct list_head *l) put_page(page); } else { putback_lru_page(page); + dec_node_page_state(page, NR_ISOLATED_ANON + + page_is_file_cache(page)); } } } @@ -1121,8 +1121,15 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page, * restored. */ list_del(&page->lru); - dec_node_page_state(page, NR_ISOLATED_ANON + - page_is_file_cache(page)); + + /* + * Compaction can migrate also non-LRU pages which are + * not accounted to NR_ISOLATED_*. They can be recognized + * as __PageMovable + */ + if (likely(!__PageMovable(page))) + dec_node_page_state(page, NR_ISOLATED_ANON + + page_is_file_cache(page)); } /* -- 2.9.3 -- Michal Hocko SUSE Labs