From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id BA1276B0022 for ; Sat, 24 Mar 2018 16:11:14 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id f194-v6so4808120lff.6 for ; Sat, 24 Mar 2018 13:11:14 -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 t130-v6sor2928048lff.33.2018.03.24.13.11.12 for (Google Transport Security); Sat, 24 Mar 2018 13:11:13 -0700 (PDT) Date: Sat, 24 Mar 2018 23:11:10 +0300 From: Vladimir Davydov Subject: Re: [PATCH 09/10] mm: Iterate only over charged shrinkers during memcg shrink_slab() Message-ID: <20180324201109.r4udxibbg4t23apg@esperanza> References: <152163840790.21546.980703278415599202.stgit@localhost.localdomain> <152163857170.21546.16040899989532143840.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <152163857170.21546.16040899989532143840.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 04:22:51PM +0300, Kirill Tkhai wrote: > Using the preparations made in previous patches, in case of memcg > shrink, we may avoid shrinkers, which are not set in memcg's shrinkers > bitmap. To do that, we separate iterations over memcg-aware and > !memcg-aware shrinkers, and memcg-aware shrinkers are chosen > via for_each_set_bit() from the bitmap. In case of big nodes, > having many isolated environments, this gives significant > performance growth. See next patch for the details. > > Note, that the patch does not respect to empty memcg shrinkers, > since we never clear the bitmap bits after we set it once. > Their shrinkers will be called again, with no shrinked objects > as result. This functionality is provided by next patch. > > Signed-off-by: Kirill Tkhai > --- > mm/vmscan.c | 54 +++++++++++++++++++++++++++++++++++++++++------------- > 1 file changed, 41 insertions(+), 13 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 265cf069b470..e1fd16bc7a9b 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -327,6 +327,8 @@ static int alloc_shrinker_id(struct shrinker *shrinker) > > if (!(shrinker->flags & SHRINKER_MEMCG_AWARE)) > return 0; > + BUG_ON(!(shrinker->flags & SHRINKER_NUMA_AWARE)); > + > retry: > ida_pre_get(&bitmap_id_ida, GFP_KERNEL); > down_write(&bitmap_rwsem); > @@ -366,7 +368,8 @@ static void add_shrinker(struct shrinker *shrinker) > down_write(&shrinker_rwsem); > if (shrinker->flags & SHRINKER_MEMCG_AWARE) > mcg_shrinkers[shrinker->id] = shrinker; > - list_add_tail(&shrinker->list, &shrinker_list); > + else > + list_add_tail(&shrinker->list, &shrinker_list); I don't think we should remove per-memcg shrinkers from the global shrinker list - this is confusing. It won't be critical if we iterate over all shrinkers on global reclaim, will it? > up_write(&shrinker_rwsem); > } > > @@ -701,6 +705,39 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, > if (!down_read_trylock(&shrinker_rwsem)) > goto out; > > +#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) > + if (!memcg_kmem_enabled() || memcg) { > + struct shrinkers_map *map; > + int i; > + > + map = rcu_dereference_protected(SHRINKERS_MAP(memcg), true); > + if (map) { > + for_each_set_bit(i, map->map[nid], bitmap_nr_ids) { > + struct shrink_control sc = { > + .gfp_mask = gfp_mask, > + .nid = nid, > + .memcg = memcg, > + }; > + > + shrinker = mcg_shrinkers[i]; > + if (!shrinker) { > + clear_bit(i, map->map[nid]); > + continue; > + } > + freed += do_shrink_slab(&sc, shrinker, priority); > + > + if (rwsem_is_contended(&shrinker_rwsem)) { > + freed = freed ? : 1; > + goto unlock; > + } > + } > + } > + > + if (memcg_kmem_enabled() && memcg) > + goto unlock; May be, factor this out to a separate function, say shrink_slab_memcg? Just for the sake of code legibility.