From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id 849776B0028 for ; Sat, 24 Mar 2018 15:45:45 -0400 (EDT) Received: by mail-lf0-f69.google.com with SMTP id u129-v6so4910534lff.9 for ; Sat, 24 Mar 2018 12:45:45 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id y17sor2909105lji.67.2018.03.24.12.45.43 for (Google Transport Security); Sat, 24 Mar 2018 12:45:44 -0700 (PDT) Date: Sat, 24 Mar 2018 22:45:40 +0300 From: Vladimir Davydov Subject: Re: [PATCH 08/10] mm: Set bit in memcg shrinker bitmap on first list_lru item apearance Message-ID: <20180324194540.rvejbnjg6knkwwia@esperanza> References: <152163840790.21546.980703278415599202.stgit@localhost.localdomain> <152163856059.21546.11414341109878480074.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <152163856059.21546.11414341109878480074.stgit@localhost.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Kirill Tkhai Cc: viro@zeniv.linux.org.uk, hannes@cmpxchg.org, mhocko@kernel.org, akpm@linux-foundation.org, tglx@linutronix.de, pombredanne@nexb.com, stummala@codeaurora.org, gregkh@linuxfoundation.org, sfr@canb.auug.org.au, guro@fb.com, mka@chromium.org, penguin-kernel@I-love.SAKURA.ne.jp, chris@chris-wilson.co.uk, longman@redhat.com, minchan@kernel.org, hillf.zj@alibaba-inc.com, ying.huang@intel.com, mgorman@techsingularity.net, shakeelb@google.com, jbacik@fb.com, linux@roeck-us.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org On Wed, Mar 21, 2018 at 04:22:40PM +0300, Kirill Tkhai wrote: > Introduce set_shrinker_bit() function to set shrinker-related > bit in memcg shrinker bitmap, and set the bit after the first > item is added and in case of reparenting destroyed memcg's items. > > This will allow next patch to make shrinkers be called only, > in case of they have charged objects at the moment, and > to improve shrink_slab() performance. > > Signed-off-by: Kirill Tkhai > --- > include/linux/shrinker.h | 7 +++++++ > mm/list_lru.c | 22 ++++++++++++++++++++-- > mm/vmscan.c | 7 +++++++ > 3 files changed, 34 insertions(+), 2 deletions(-) > > diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h > index 738de8ef5246..24aeed1bc332 100644 > --- a/include/linux/shrinker.h > +++ b/include/linux/shrinker.h > @@ -78,4 +78,11 @@ struct shrinker { > > extern __must_check int register_shrinker(struct shrinker *); > extern void unregister_shrinker(struct shrinker *); > +#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) > +extern void set_shrinker_bit(struct mem_cgroup *, int, int); > +#else > +static inline void set_shrinker_bit(struct mem_cgroup *memcg, int node, int id) > +{ > +} > +#endif IMO this function, as well as other shrinker bitmap manipulation functions, should be defined in memcontrol.[hc] and have mem_cgroup_ prefix. > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 9d1df5d90eca..265cf069b470 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -378,6 +378,13 @@ static void del_shrinker(struct shrinker *shrinker) > list_del(&shrinker->list); > up_write(&shrinker_rwsem); > } > + > +void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int nr) > +{ > + struct shrinkers_map *map = SHRINKERS_MAP(memcg); > + > + set_bit(nr, map->map[nid]); > +} Shouldn't we use rcu_read_lock here? After all, the map can be reallocated right from under our feet.