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=-14.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=ham 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 7FDACFC6194 for ; Thu, 7 Nov 2019 02:52:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 237122187F for ; Thu, 7 Nov 2019 02:52:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="YvIaRGMJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 237122187F Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CBDF26B0007; Wed, 6 Nov 2019 21:52:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C480F6B0008; Wed, 6 Nov 2019 21:52:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B10516B000D; Wed, 6 Nov 2019 21:52:19 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0175.hostedemail.com [216.40.44.175]) by kanga.kvack.org (Postfix) with ESMTP id 992156B0007 for ; Wed, 6 Nov 2019 21:52:19 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 11867181AEF1F for ; Thu, 7 Nov 2019 02:52:19 +0000 (UTC) X-FDA: 76127957598.04.pot38_1421b9af49e23 X-HE-Tag: pot38_1421b9af49e23 X-Filterd-Recvd-Size: 12625 Received: from mail-oi1-f196.google.com (mail-oi1-f196.google.com [209.85.167.196]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Thu, 7 Nov 2019 02:52:18 +0000 (UTC) Received: by mail-oi1-f196.google.com with SMTP id y194so665993oie.4 for ; Wed, 06 Nov 2019 18:52:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WAXXWA8L5ITD9neXsElL+Vjflm2Yh4OLeHgcVUxIxCw=; b=YvIaRGMJkMJ44J7UiBadMBvlgvPUpFKMUzAuIJZQVtlWJz5eIXoXJ2Ikj2W4c+jMOH zaE2k2WhuoQiCsceC7glsLNT1lDt95L1nEqOMlhS+QHrWzHd0FFVQhMKDamFdki/whBI xu/1GismT77URf9K3yYHircrmxBe2m/Cq+nmiunqDPbRPptHnsjQSEFsPQifpZ0HcOGw sDDvDmcEDn8omi18g1YxxUDbiOE2q9SLY5nB8UK0ybK/2f3IkbJJhWfej9lH0EUYK5Ms eZmbUUqYyAduzccRmJrs+3GNQBMra67O7vhpeZoXmHlUHZx3U2l+vMqQawdLobzVUN4W h9TA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WAXXWA8L5ITD9neXsElL+Vjflm2Yh4OLeHgcVUxIxCw=; b=YbNnQ2FW3ULdWAzn6NoYNmJ8Q2w5fNJPW2k+vcyPzhSgHQg4+UCGS9ZsRpMoTjNMcz Lp4P2Wsj3PMlgADPK3UaYZ+EkGiej5tJG3YfRMr5JUopMPQk7NeEovxDG5qJKbS3hFQy sgL/fTcE+pYyWkrHznX20Kd8oaT4SW7yHSQy9osPSuPrKqOjaFI54u45inAC1BA+KADh fVtpQcjoEWTxSo2blvOAVdptIFSG1NT4BYEnUmmRYwWQoj1VAq+zPFGleYMEcky2IFjQ EzXfX2uqlngOeL2ksG1q0Rsi6U+2jdqszlUrUVLx61RW6PD+EKGsoGvyTrbAbePhnKUy V/uw== X-Gm-Message-State: APjAAAU3nImbmBpMJGW18By5Nb0mikj/X6OezZeVOJVjSZrljU7MKgT1 e21yW74WHYj0gon5wc4d/udfs23rfWyWOlIi1pYLDH2Q X-Google-Smtp-Source: APXvYqw8EeQvtFTwCWBBCkwD7rORK0nCMxDrAI5kmGBl30fq6yDJUp91bNexbzN+YGA5IK3bOPFfKNI49xgQik8tH10= X-Received: by 2002:aca:f1c5:: with SMTP id p188mr1096915oih.125.1573095137181; Wed, 06 Nov 2019 18:52:17 -0800 (PST) MIME-Version: 1.0 References: <20190603210746.15800-1-hannes@cmpxchg.org> <20190603210746.15800-9-hannes@cmpxchg.org> In-Reply-To: <20190603210746.15800-9-hannes@cmpxchg.org> From: Shakeel Butt Date: Wed, 6 Nov 2019 18:52:06 -0800 Message-ID: Subject: Re: [PATCH 08/11] mm: vmscan: harmonize writeback congestion tracking for nodes & memcgs To: Johannes Weiner Cc: Andrew Morton , Andrey Ryabinin , Suren Baghdasaryan , Michal Hocko , Linux MM , Cgroups , LKML , Kernel Team Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jun 3, 2019 at 3:04 PM Johannes Weiner wrote: > > The current writeback congestion tracking has separate flags for > kswapd reclaim (node level) and cgroup limit reclaim (memcg-node > level). This is unnecessarily complicated: the lruvec is an existing > abstraction layer for that node-memcg intersection. > > Introduce lruvec->flags and LRUVEC_CONGESTED. Then track that at the > reclaim root level, which is either the NUMA node for global reclaim, > or the cgroup-node intersection for cgroup reclaim. > > Signed-off-by: Johannes Weiner Reviewed-by: Shakeel Butt > --- > include/linux/memcontrol.h | 6 +-- > include/linux/mmzone.h | 11 ++++-- > mm/vmscan.c | 80 ++++++++++++-------------------------- > 3 files changed, 36 insertions(+), 61 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index fc32cfaebf32..d33e09c51acc 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -144,9 +144,6 @@ struct mem_cgroup_per_node { > unsigned long usage_in_excess;/* Set to the value by which */ > /* the soft limit is exceeded*/ > bool on_tree; > - bool congested; /* memcg has many dirty pages */ > - /* backed by a congested BDI */ > - > struct mem_cgroup *memcg; /* Back pointer, we cannot */ > /* use container_of */ > }; > @@ -401,6 +398,9 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg, > goto out; > } > > + if (!memcg) > + memcg = root_mem_cgroup; > + > mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id); > lruvec = &mz->lruvec; > out: > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 95d63a395f40..b3ab64cf5619 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -293,6 +293,12 @@ struct zone_reclaim_stat { > unsigned long recent_scanned[2]; > }; > > +enum lruvec_flags { > + LRUVEC_CONGESTED, /* lruvec has many dirty pages > + * backed by a congested BDI > + */ > +}; > + > struct lruvec { > struct list_head lists[NR_LRU_LISTS]; > struct zone_reclaim_stat reclaim_stat; > @@ -300,6 +306,8 @@ struct lruvec { > atomic_long_t inactive_age; > /* Refaults at the time of last reclaim cycle */ > unsigned long refaults; > + /* Various lruvec state flags (enum lruvec_flags) */ > + unsigned long flags; > #ifdef CONFIG_MEMCG > struct pglist_data *pgdat; > #endif > @@ -562,9 +570,6 @@ struct zone { > } ____cacheline_internodealigned_in_smp; > > enum pgdat_flags { > - PGDAT_CONGESTED, /* pgdat has many dirty pages backed by > - * a congested BDI > - */ > PGDAT_DIRTY, /* reclaim scanning has recently found > * many dirty file pages at the tail > * of the LRU. > diff --git a/mm/vmscan.c b/mm/vmscan.c > index ee79b39d0538..eb535c572733 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -267,29 +267,6 @@ static bool writeback_working(struct scan_control *sc) > #endif > return false; > } > - > -static void set_memcg_congestion(pg_data_t *pgdat, > - struct mem_cgroup *memcg, > - bool congested) > -{ > - struct mem_cgroup_per_node *mn; > - > - if (!memcg) > - return; > - > - mn = mem_cgroup_nodeinfo(memcg, pgdat->node_id); > - WRITE_ONCE(mn->congested, congested); > -} > - > -static bool memcg_congested(pg_data_t *pgdat, > - struct mem_cgroup *memcg) > -{ > - struct mem_cgroup_per_node *mn; > - > - mn = mem_cgroup_nodeinfo(memcg, pgdat->node_id); > - return READ_ONCE(mn->congested); > - > -} > #else > static bool cgroup_reclaim(struct scan_control *sc) > { > @@ -300,18 +277,6 @@ static bool writeback_working(struct scan_control *sc) > { > return true; > } > - > -static inline void set_memcg_congestion(struct pglist_data *pgdat, > - struct mem_cgroup *memcg, bool congested) > -{ > -} > - > -static inline bool memcg_congested(struct pglist_data *pgdat, > - struct mem_cgroup *memcg) > -{ > - return false; > - > -} > #endif > > /* > @@ -2659,12 +2624,6 @@ static inline bool should_continue_reclaim(struct pglist_data *pgdat, > return true; > } > > -static bool pgdat_memcg_congested(pg_data_t *pgdat, struct mem_cgroup *memcg) > -{ > - return test_bit(PGDAT_CONGESTED, &pgdat->flags) || > - (memcg && memcg_congested(pgdat, memcg)); > -} > - > static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) > { > struct mem_cgroup *root = sc->target_mem_cgroup; > @@ -2748,8 +2707,11 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) > struct reclaim_state *reclaim_state = current->reclaim_state; > struct mem_cgroup *root = sc->target_mem_cgroup; > unsigned long nr_reclaimed, nr_scanned; > + struct lruvec *target_lruvec; > bool reclaimable = false; > > + target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat); > + > again: > memset(&sc->nr, 0, sizeof(sc->nr)); > > @@ -2792,14 +2754,6 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) > if (sc->nr.writeback && sc->nr.writeback == sc->nr.taken) > set_bit(PGDAT_WRITEBACK, &pgdat->flags); > > - /* > - * Tag a node as congested if all the dirty pages > - * scanned were backed by a congested BDI and > - * wait_iff_congested will stall. > - */ > - if (sc->nr.dirty && sc->nr.dirty == sc->nr.congested) > - set_bit(PGDAT_CONGESTED, &pgdat->flags); > - > /* Allow kswapd to start writing pages during reclaim.*/ > if (sc->nr.unqueued_dirty == sc->nr.file_taken) > set_bit(PGDAT_DIRTY, &pgdat->flags); > @@ -2815,12 +2769,17 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) > } > > /* > + * Tag a node/memcg as congested if all the dirty pages > + * scanned were backed by a congested BDI and > + * wait_iff_congested will stall. > + * > * Legacy memcg will stall in page writeback so avoid forcibly > * stalling in wait_iff_congested(). > */ > - if (cgroup_reclaim(sc) && writeback_working(sc) && > + if ((current_is_kswapd() || > + (cgroup_reclaim(sc) && writeback_working(sc))) && > sc->nr.dirty && sc->nr.dirty == sc->nr.congested) > - set_memcg_congestion(pgdat, root, true); > + set_bit(LRUVEC_CONGESTED, &target_lruvec->flags); > > /* > * Stall direct reclaim for IO completions if underlying BDIs > @@ -2828,8 +2787,9 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) > * starts encountering unqueued dirty pages or cycling through > * the LRU too quickly. > */ > - if (!sc->hibernation_mode && !current_is_kswapd() && > - current_may_throttle() && pgdat_memcg_congested(pgdat, root)) > + if (!current_is_kswapd() && current_may_throttle() && > + !sc->hibernation_mode && > + test_bit(LRUVEC_CONGESTED, &target_lruvec->flags)) > wait_iff_congested(BLK_RW_ASYNC, HZ/10); > > if (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed, > @@ -3043,8 +3003,16 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > if (zone->zone_pgdat == last_pgdat) > continue; > last_pgdat = zone->zone_pgdat; > + > snapshot_refaults(sc->target_mem_cgroup, zone->zone_pgdat); > - set_memcg_congestion(last_pgdat, sc->target_mem_cgroup, false); > + > + if (cgroup_reclaim(sc)) { > + struct lruvec *lruvec; > + > + lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, > + zone->zone_pgdat); > + clear_bit(LRUVEC_CONGESTED, &lruvec->flags); > + } > } > > delayacct_freepages_end(); > @@ -3419,7 +3387,9 @@ static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) > /* Clear pgdat state for congested, dirty or under writeback. */ > static void clear_pgdat_congested(pg_data_t *pgdat) > { > - clear_bit(PGDAT_CONGESTED, &pgdat->flags); > + struct lruvec *lruvec = mem_cgroup_lruvec(NULL, pgdat); > + > + clear_bit(LRUVEC_CONGESTED, &lruvec->flags); > clear_bit(PGDAT_DIRTY, &pgdat->flags); > clear_bit(PGDAT_WRITEBACK, &pgdat->flags); > } > -- > 2.21.0 >