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,NICE_REPLY_A,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 BCAD0C433E0 for ; Mon, 25 Jan 2021 10:51:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72AEE22D50 for ; Mon, 25 Jan 2021 10:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727668AbhAYKvO (ORCPT ); Mon, 25 Jan 2021 05:51:14 -0500 Received: from relay.sw.ru ([185.231.240.75]:49414 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727635AbhAYKrk (ORCPT ); Mon, 25 Jan 2021 05:47:40 -0500 Received: from [192.168.15.14] by relay.sw.ru with esmtp (Exim 4.94) (envelope-from ) id 1l3yGy-000TKx-0R; Mon, 25 Jan 2021 12:35:00 +0300 Subject: Re: [v4 PATCH 08/11] mm: vmscan: use per memcg nr_deferred of shrinker To: Yang Shi , guro@fb.com, shakeelb@google.com, david@fromorbit.com, hannes@cmpxchg.org, mhocko@suse.com, akpm@linux-foundation.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210121230621.654304-1-shy828301@gmail.com> <20210121230621.654304-9-shy828301@gmail.com> From: Kirill Tkhai Message-ID: Date: Mon, 25 Jan 2021 12:35:06 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210121230621.654304-9-shy828301@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22.01.2021 02:06, Yang Shi wrote: > Use per memcg's nr_deferred for memcg aware shrinkers. The shrinker's nr_deferred > will be used in the following cases: > 1. Non memcg aware shrinkers > 2. !CONFIG_MEMCG > 3. memcg is disabled by boot parameter > > Signed-off-by: Yang Shi > --- > mm/vmscan.c | 81 +++++++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 69 insertions(+), 12 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 722aa71b13b2..d8e77ea13815 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -359,6 +359,27 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) > up_write(&shrinker_rwsem); > } > > +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker, > + struct mem_cgroup *memcg) > +{ > + struct shrinker_info *info; > + > + info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, > + true); Since now these rcu_dereference_protected() are in separate functions and there is no taking a lock near them, it seems it would be better to underling the desired lock with rcu_dereference_protected(, lockdep_assert_held(lock_you_need_here_locked)); > + return atomic_long_xchg(&info->nr_deferred[shrinker->id], 0); > +} > + > +static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, > + struct mem_cgroup *memcg) > +{ > + struct shrinker_info *info; > + > + info = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, > + true); > + > + return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); > +} > + > static bool cgroup_reclaim(struct scan_control *sc) > { > return sc->target_mem_cgroup; > @@ -397,6 +418,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) > { > } > > +static long count_nr_deferred_memcg(int nid, struct shrinker *shrinker, > + struct mem_cgroup *memcg) > +{ > + return 0; > +} > + > +static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, > + struct mem_cgroup *memcg) > +{ > + return 0; > +} > + > static bool cgroup_reclaim(struct scan_control *sc) > { > return false; > @@ -408,6 +441,39 @@ static bool writeback_throttling_sane(struct scan_control *sc) > } > #endif > > +static long count_nr_deferred(struct shrinker *shrinker, > + struct shrink_control *sc) > +{ > + int nid = sc->nid; > + > + if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > + nid = 0; > + > + if (sc->memcg && > + (shrinker->flags & SHRINKER_MEMCG_AWARE)) > + return count_nr_deferred_memcg(nid, shrinker, > + sc->memcg); > + > + return atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > +} > + > + > +static long set_nr_deferred(long nr, struct shrinker *shrinker, > + struct shrink_control *sc) > +{ > + int nid = sc->nid; > + > + if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > + nid = 0; > + > + if (sc->memcg && > + (shrinker->flags & SHRINKER_MEMCG_AWARE)) > + return set_nr_deferred_memcg(nr, nid, shrinker, > + sc->memcg); > + > + return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]); > +} > + > /* > * This misses isolated pages which are not accounted for to save counters. > * As the data only determines if reclaim or compaction continues, it is > @@ -544,14 +610,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > long freeable; > long nr; > long new_nr; > - int nid = shrinkctl->nid; > long batch_size = shrinker->batch ? shrinker->batch > : SHRINK_BATCH; > long scanned = 0, next_deferred; > > - if (!(shrinker->flags & SHRINKER_NUMA_AWARE)) > - nid = 0; > - > freeable = shrinker->count_objects(shrinker, shrinkctl); > if (freeable == 0 || freeable == SHRINK_EMPTY) > return freeable; > @@ -561,7 +623,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > * and zero it so that other concurrent shrinker invocations > * don't also do this scanning work. > */ > - nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0); > + nr = count_nr_deferred(shrinker, shrinkctl); > > total_scan = nr; > if (shrinker->seeks) { > @@ -652,14 +714,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > next_deferred = 0; > /* > * move the unused scan count back into the shrinker in a > - * manner that handles concurrent updates. If we exhausted the > - * scan, there is no need to do an update. > + * manner that handles concurrent updates. > */ > - if (next_deferred > 0) > - new_nr = atomic_long_add_return(next_deferred, > - &shrinker->nr_deferred[nid]); > - else > - new_nr = atomic_long_read(&shrinker->nr_deferred[nid]); > + new_nr = set_nr_deferred(next_deferred, shrinker, shrinkctl); > > trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan); > return freed; >