From: Andrew Morton <akpm@linux-foundation.org>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: vdavydov.dev@gmail.com, shakeelb@google.com,
viro@zeniv.linux.org.uk, hannes@cmpxchg.org, mhocko@kernel.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, ying.huang@intel.com,
mgorman@techsingularity.net, jbacik@fb.com, linux@roeck-us.net,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
willy@infradead.org, lirongqing@baidu.com,
aryabinin@virtuozzo.com
Subject: Re: [PATCH v8 14/17] mm: Iterate only over charged shrinkers during memcg shrink_slab()
Date: Tue, 3 Jul 2018 13:58:13 -0700 [thread overview]
Message-ID: <20180703135813.ed4eef6a4a2df32fa1085e4c@linux-foundation.org> (raw)
In-Reply-To: <153063066653.1818.976035462801487910.stgit@localhost.localdomain>
On Tue, 03 Jul 2018 18:11:06 +0300 Kirill Tkhai <ktkhai@virtuozzo.com> 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 patches 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 patches.
>
> ...
>
> @@ -541,6 +555,67 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
> return freed;
> }
>
> +#ifdef CONFIG_MEMCG_KMEM
> +static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
> + struct mem_cgroup *memcg, int priority)
> +{
> + struct memcg_shrinker_map *map;
> + unsigned long freed = 0;
> + int ret, i;
> +
> + if (!memcg_kmem_enabled() || !mem_cgroup_online(memcg))
> + return 0;
> +
> + if (!down_read_trylock(&shrinker_rwsem))
> + return 0;
Why trylock? Presumably some other code path is known to hold the lock
for long periods? Dunno. Comment it, please.
> + /*
> + * 1) Caller passes only alive memcg, so map can't be NULL.
> + * 2) shrinker_rwsem protects from maps expanding.
> + */
> + map = rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_map,
> + true);
> + BUG_ON(!map);
> +
> + for_each_set_bit(i, map->map, shrinker_nr_max) {
> + struct shrink_control sc = {
> + .gfp_mask = gfp_mask,
> + .nid = nid,
> + .memcg = memcg,
> + };
> + struct shrinker *shrinker;
> +
> + shrinker = idr_find(&shrinker_idr, i);
> + if (unlikely(!shrinker)) {
> + clear_bit(i, map->map);
> + continue;
> + }
> + BUG_ON(!(shrinker->flags & SHRINKER_MEMCG_AWARE));
Fair enough as a development-time sanity check but we shouldn't need
this in production code. Or make it VM_BUG_ON(), at least.
> + /* See comment in prealloc_shrinker() */
> + if (unlikely(list_empty(&shrinker->list)))
> + continue;
> +
> + ret = do_shrink_slab(&sc, shrinker, priority);
> + freed += ret;
> +
> + if (rwsem_is_contended(&shrinker_rwsem)) {
> + freed = freed ? : 1;
> + break;
> + }
> + }
> +
> + up_read(&shrinker_rwsem);
> + return freed;
> +}
next prev parent reply other threads:[~2018-07-03 20:58 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-03 15:08 [PATCH v8 00/17] Improve shrink_slab() scalability (old complexity was O(n^2), new is O(n)) Kirill Tkhai
2018-07-03 15:08 ` [PATCH v8 01/17] list_lru: Combine code under the same define Kirill Tkhai
2018-07-03 15:08 ` [PATCH v8 02/17] mm: Introduce CONFIG_MEMCG_KMEM as combination of CONFIG_MEMCG && !CONFIG_SLOB Kirill Tkhai
2018-07-03 15:09 ` [PATCH v8 03/17] mm: Assign id to every memcg-aware shrinker Kirill Tkhai
2018-07-03 15:27 ` Matthew Wilcox
2018-07-03 15:46 ` Shakeel Butt
2018-07-03 16:17 ` Kirill Tkhai
2018-07-03 17:00 ` Shakeel Butt
2018-07-03 17:32 ` Kirill Tkhai
2018-07-12 11:13 ` Kirill Tkhai
2018-07-12 11:19 ` Kirill Tkhai
2018-07-03 17:47 ` Matthew Wilcox
2018-07-03 20:39 ` Al Viro
2018-07-03 15:46 ` Kirill Tkhai
2018-07-03 17:58 ` Matthew Wilcox
2018-07-03 19:12 ` Kirill Tkhai
2018-07-03 19:19 ` Shakeel Butt
2018-07-03 19:25 ` Matthew Wilcox
2018-07-03 19:54 ` Shakeel Butt
2018-07-03 15:09 ` [PATCH v8 04/17] memcg: Move up for_each_mem_cgroup{, _tree} defines Kirill Tkhai
2018-07-03 15:09 ` [PATCH v8 05/17] mm: Assign memcg-aware shrinkers bitmap to memcg Kirill Tkhai
2018-07-03 20:50 ` Andrew Morton
2018-07-04 15:51 ` Kirill Tkhai
2018-07-05 22:10 ` Andrew Morton
2018-07-06 17:50 ` Vladimir Davydov
2018-07-05 22:50 ` Matthew Wilcox
2018-07-06 17:30 ` Vladimir Davydov
2018-07-03 15:09 ` [PATCH v8 06/17] mm: Refactoring in workingset_init() Kirill Tkhai
2018-07-03 15:09 ` [PATCH v8 07/17] fs: Refactoring in alloc_super() Kirill Tkhai
2018-07-03 15:09 ` [PATCH v8 08/17] fs: Propagate shrinker::id to list_lru Kirill Tkhai
2018-07-03 15:10 ` [PATCH v8 09/17] list_lru: Add memcg argument to list_lru_from_kmem() Kirill Tkhai
2018-07-03 15:10 ` [PATCH v8 10/17] list_lru: Pass dst_memcg argument to memcg_drain_list_lru_node() Kirill Tkhai
2018-07-03 15:10 ` [PATCH v8 11/17] list_lru: Pass lru " Kirill Tkhai
2018-07-03 15:10 ` [PATCH v8 12/17] mm: Export mem_cgroup_is_root() Kirill Tkhai
2018-07-03 15:10 ` [PATCH v8 13/17] mm: Set bit in memcg shrinker bitmap on first list_lru item apearance Kirill Tkhai
2018-07-03 20:54 ` Andrew Morton
2018-07-03 15:11 ` [PATCH v8 14/17] mm: Iterate only over charged shrinkers during memcg shrink_slab() Kirill Tkhai
2018-07-03 20:58 ` Andrew Morton [this message]
2018-07-04 14:56 ` Kirill Tkhai
2018-07-03 15:11 ` [PATCH v8 15/17] mm: Generalize shrink_slab() calls in shrink_node() Kirill Tkhai
2018-07-03 15:11 ` [PATCH v8 16/17] mm: Add SHRINK_EMPTY shrinker methods return value Kirill Tkhai
2018-07-03 15:11 ` [PATCH v8 17/17] mm: Clear shrinker bit if there are no objects related to memcg Kirill Tkhai
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