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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 DE524C433FE for ; Wed, 22 Sep 2021 08:11:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7D3B6124A for ; Wed, 22 Sep 2021 08:11:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233687AbhIVIMm (ORCPT ); Wed, 22 Sep 2021 04:12:42 -0400 Received: from outbound-smtp61.blacknight.com ([46.22.136.249]:47745 "EHLO outbound-smtp61.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233532AbhIVIMh (ORCPT ); Wed, 22 Sep 2021 04:12:37 -0400 Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp61.blacknight.com (Postfix) with ESMTPS id 5D368FBD84 for ; Wed, 22 Sep 2021 09:11:07 +0100 (IST) Received: (qmail 29350 invoked from network); 22 Sep 2021 08:11:07 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.29]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 22 Sep 2021 08:11:07 -0000 Date: Wed, 22 Sep 2021 09:11:04 +0100 From: Mel Gorman To: Yang Shi Cc: Linux-MM , NeilBrown , Theodore Ts'o , Andreas Dilger , "Darrick J . Wong" , Matthew Wilcox , Michal Hocko , Dave Chinner , Rik van Riel , Vlastimil Babka , Johannes Weiner , Jonathan Corbet , Linux-fsdevel , LKML Subject: Re: [PATCH 2/5] mm/vmscan: Throttle reclaim and compaction when too may pages are isolated Message-ID: <20210922081104.GV3959@techsingularity.net> References: <20210920085436.20939-1-mgorman@techsingularity.net> <20210920085436.20939-3-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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 21, 2021 at 11:45:19AM -0700, Yang Shi wrote: > On Mon, Sep 20, 2021 at 1:55 AM Mel Gorman wrote: > > > > Page reclaim throttles on congestion if too many parallel reclaim instances > > have isolated too many pages. This makes no sense, excessive parallelisation > > has nothing to do with writeback or congestion. > > > > This patch creates an additional workqueue to sleep on when too many > > pages are isolated. The throttled tasks are woken when the number > > of isolated pages is reduced or a timeout occurs. There may be > > some false positive wakeups for GFP_NOIO/GFP_NOFS callers but > > the tasks will throttle again if necessary. > > > > Signed-off-by: Mel Gorman > > --- > > include/linux/mmzone.h | 4 +++- > > include/trace/events/vmscan.h | 4 +++- > > mm/compaction.c | 2 +- > > mm/internal.h | 2 ++ > > mm/page_alloc.c | 6 +++++- > > mm/vmscan.c | 22 ++++++++++++++++------ > > 6 files changed, 30 insertions(+), 10 deletions(-) > > > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > > index ef0a63ebd21d..ca65d6a64bdd 100644 > > --- a/include/linux/mmzone.h > > +++ b/include/linux/mmzone.h > > @@ -275,6 +275,8 @@ enum lru_list { > > > > enum vmscan_throttle_state { > > VMSCAN_THROTTLE_WRITEBACK, > > + VMSCAN_THROTTLE_ISOLATED, > > + NR_VMSCAN_THROTTLE, > > }; > > > > #define for_each_lru(lru) for (lru = 0; lru < NR_LRU_LISTS; lru++) > > @@ -846,7 +848,7 @@ typedef struct pglist_data { > > int node_id; > > wait_queue_head_t kswapd_wait; > > wait_queue_head_t pfmemalloc_wait; > > - wait_queue_head_t reclaim_wait; /* wq for throttling reclaim */ > > + wait_queue_head_t reclaim_wait[NR_VMSCAN_THROTTLE]; > > atomic_t nr_reclaim_throttled; /* nr of throtted tasks */ > > unsigned long nr_reclaim_start; /* nr pages written while throttled > > * when throttling started. */ > > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h > > index c317f9fe0d17..d4905bd9e9c4 100644 > > --- a/include/trace/events/vmscan.h > > +++ b/include/trace/events/vmscan.h > > @@ -28,10 +28,12 @@ > > ) : "RECLAIM_WB_NONE" > > > > #define _VMSCAN_THROTTLE_WRITEBACK (1 << VMSCAN_THROTTLE_WRITEBACK) > > +#define _VMSCAN_THROTTLE_ISOLATED (1 << VMSCAN_THROTTLE_ISOLATED) > > > > #define show_throttle_flags(flags) \ > > (flags) ? __print_flags(flags, "|", \ > > - {_VMSCAN_THROTTLE_WRITEBACK, "VMSCAN_THROTTLE_WRITEBACK"} \ > > + {_VMSCAN_THROTTLE_WRITEBACK, "VMSCAN_THROTTLE_WRITEBACK"}, \ > > + {_VMSCAN_THROTTLE_ISOLATED, "VMSCAN_THROTTLE_ISOLATED"} \ > > ) : "VMSCAN_THROTTLE_NONE" > > > > > > diff --git a/mm/compaction.c b/mm/compaction.c > > index bfc93da1c2c7..221c9c10ad7e 100644 > > --- a/mm/compaction.c > > +++ b/mm/compaction.c > > @@ -822,7 +822,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > > if (cc->mode == MIGRATE_ASYNC) > > return -EAGAIN; > > > > - congestion_wait(BLK_RW_ASYNC, HZ/10); > > + reclaim_throttle(pgdat, VMSCAN_THROTTLE_ISOLATED, HZ/10); > > It seems waking up tasks is missed in compaction's > too_many_isolated(). There are two too_many_isolated(), one is for > compaction, the other is for reclaimer. I saw the waking up code was > added to the reclaimer's in the below. Or the compaction one is left > out intentionally? > Compaction one was left out accidentally, I'll fix it. Thanks. -- Mel Gorman SUSE Labs