From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: viro@zeniv.linux.org.uk, hannes@cmpxchg.org, mhocko@kernel.org,
vdavydov.dev@gmail.com, ktkhai@virtuozzo.com,
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
Subject: [PATCH 10/10] mm: Clear shrinker bit if there are no objects related to memcg
Date: Wed, 21 Mar 2018 16:23:01 +0300 [thread overview]
Message-ID: <152163858159.21546.2876185232270486710.stgit@localhost.localdomain> (raw)
In-Reply-To: <152163840790.21546.980703278415599202.stgit@localhost.localdomain>
To avoid further unneed calls of do_shrink_slab()
for shrinkers, which already do not have any charged
objects in a memcg, their bits have to be cleared.
This patch introduces new return value SHRINK_EMPTY,
which will be used in case of there is no charged
objects in shrinker. We can't use 0 instead of that,
as a shrinker may return 0, when it has very small
amount of objects.
To prevent race with parallel list lru add, we call
do_shrink_slab() once again, after the bit is cleared.
So, if there is a new object, we never miss it, and
the bit will be restored again.
The below test shows significant performance growths
after using the patchset:
$echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
$mkdir /sys/fs/cgroup/memory/ct
$echo 4000M > /sys/fs/cgroup/memory/ct/memory.kmem.limit_in_bytes
$for i in `seq 0 4000`; do mkdir /sys/fs/cgroup/memory/ct/$i; echo $$ > /sys/fs/cgroup/memory/ct/$i/cgroup.procs; mkdir -p s/$i; mount -t tmpfs $i s/$i; touch s/$i/file; done
Then 4 drop_caches:
$time echo 3 > /proc/sys/vm/drop_caches
Times of drop_caches:
*Before (4 iterations)*
0.00user 6.80system 0:06.82elapsed 99%CPU
0.00user 4.61system 0:04.62elapsed 99%CPU
0.00user 4.61system 0:04.61elapsed 99%CPU
0.00user 4.61system 0:04.61elapsed 99%CPU
*After (4 iterations)*
0.00user 0.93system 0:00.94elapsed 99%CPU
0.00user 0.00system 0:00.01elapsed 80%CPU
0.00user 0.00system 0:00.01elapsed 80%CPU
0.00user 0.00system 0:00.01elapsed 81%CPU
4.61s/0.01s = 461 times faster.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
fs/super.c | 3 +++
include/linux/shrinker.h | 1 +
mm/vmscan.c | 21 ++++++++++++++++++---
mm/workingset.c | 3 +++
4 files changed, 25 insertions(+), 3 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 1f3dc4eab409..788ea4e6a40b 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -133,6 +133,9 @@ static unsigned long super_cache_count(struct shrinker *shrink,
total_objects += list_lru_shrink_count(&sb->s_dentry_lru, sc);
total_objects += list_lru_shrink_count(&sb->s_inode_lru, sc);
+ if (!total_objects)
+ return SHRINK_EMPTY;
+
total_objects = vfs_pressure_ratio(total_objects);
return total_objects;
}
diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 24aeed1bc332..b23180deb928 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -34,6 +34,7 @@ struct shrink_control {
};
#define SHRINK_STOP (~0UL)
+#define SHRINK_EMPTY (~0UL - 1)
/*
* A callback you can register to apply pressure to ageable caches.
*
diff --git a/mm/vmscan.c b/mm/vmscan.c
index e1fd16bc7a9b..1fc05e8bde04 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -387,6 +387,7 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int nr)
{
struct shrinkers_map *map = SHRINKERS_MAP(memcg);
+ smp_mb__before_atomic(); /* Pairs with mb in shrink_slab() */
set_bit(nr, map->map[nid]);
}
#else /* CONFIG_MEMCG && !CONFIG_SLOB */
@@ -568,8 +569,8 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
long scanned = 0, next_deferred;
freeable = shrinker->count_objects(shrinker, shrinkctl);
- if (freeable == 0)
- return 0;
+ if (freeable == 0 || freeable == SHRINK_EMPTY)
+ return freeable;
/*
* copy the current shrinker scan count into a local variable
@@ -708,6 +709,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
if (!memcg_kmem_enabled() || memcg) {
struct shrinkers_map *map;
+ unsigned long ret;
int i;
map = rcu_dereference_protected(SHRINKERS_MAP(memcg), true);
@@ -724,7 +726,20 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
clear_bit(i, map->map[nid]);
continue;
}
- freed += do_shrink_slab(&sc, shrinker, priority);
+ if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+ sc.nid = 0;
+ ret = do_shrink_slab(&sc, shrinker, priority);
+ if (ret == SHRINK_EMPTY) {
+ clear_bit(i, map->map[nid]);
+ /* pairs with mb in set_shrinker_bit() */
+ smp_mb__after_atomic();
+ ret = do_shrink_slab(&sc, shrinker, priority);
+ if (ret == SHRINK_EMPTY)
+ ret = 0;
+ else
+ set_bit(i, map->map[nid]);
+ }
+ freed += ret;
if (rwsem_is_contended(&shrinker_rwsem)) {
freed = freed ? : 1;
diff --git a/mm/workingset.c b/mm/workingset.c
index 62c9eb000c4f..dc05574f0a07 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -402,6 +402,9 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
}
max_nodes = cache >> (RADIX_TREE_MAP_SHIFT - 3);
+ if (!nodes)
+ return SHRINK_EMPTY;
+
if (nodes <= max_nodes)
return 0;
return nodes - max_nodes;
next prev parent reply other threads:[~2018-03-21 13:23 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-21 13:21 [PATCH 00/10] Improve shrink_slab() scalability (old complexity was O(n^2), new is O(n)) Kirill Tkhai
2018-03-21 13:21 ` [PATCH 01/10] mm: Assign id to every memcg-aware shrinker Kirill Tkhai
2018-03-24 18:40 ` Vladimir Davydov
2018-03-26 15:09 ` Kirill Tkhai
2018-03-26 15:14 ` Matthew Wilcox
2018-03-26 15:38 ` Kirill Tkhai
2018-03-27 9:15 ` Vladimir Davydov
2018-03-27 15:09 ` Kirill Tkhai
2018-03-27 15:48 ` Vladimir Davydov
2018-03-28 10:30 ` Kirill Tkhai
2018-03-28 11:02 ` Vladimir Davydov
2018-03-21 13:21 ` [PATCH 02/10] mm: Maintain memcg-aware shrinkers in mcg_shrinkers array Kirill Tkhai
2018-03-24 18:45 ` Vladimir Davydov
2018-03-26 15:20 ` Kirill Tkhai
2018-03-26 15:34 ` Matthew Wilcox
2018-03-27 9:18 ` Vladimir Davydov
2018-03-27 15:30 ` Kirill Tkhai
2018-03-21 13:21 ` [PATCH 03/10] mm: Assign memcg-aware shrinkers bitmap to memcg Kirill Tkhai
2018-03-21 14:56 ` Matthew Wilcox
2018-03-21 15:12 ` Kirill Tkhai
2018-03-21 15:26 ` Matthew Wilcox
2018-03-21 15:43 ` Kirill Tkhai
2018-03-21 16:20 ` Matthew Wilcox
2018-03-21 16:42 ` Kirill Tkhai
2018-03-21 17:54 ` Matthew Wilcox
2018-03-22 16:39 ` Kirill Tkhai
2018-03-23 9:06 ` kbuild test robot
2018-03-23 11:26 ` Kirill Tkhai
2018-03-24 19:25 ` Vladimir Davydov
2018-03-26 15:29 ` Kirill Tkhai
2018-03-27 10:00 ` Vladimir Davydov
2018-03-27 15:17 ` Kirill Tkhai
2018-03-21 13:21 ` [PATCH 04/10] fs: Propagate shrinker::id to list_lru Kirill Tkhai
2018-03-24 18:50 ` Vladimir Davydov
2018-03-26 15:29 ` Kirill Tkhai
2018-03-21 13:22 ` [PATCH 05/10] list_lru: Add memcg argument to list_lru_from_kmem() Kirill Tkhai
2018-04-02 3:17 ` [lkp-robot] [list_lru] 42658d54ce: BUG:unable_to_handle_kernel kernel test robot
2018-04-02 8:51 ` Kirill Tkhai
2018-03-21 13:22 ` [PATCH 06/10] list_lru: Pass dst_memcg argument to memcg_drain_list_lru_node() Kirill Tkhai
2018-03-24 19:32 ` Vladimir Davydov
2018-03-26 15:30 ` Kirill Tkhai
2018-03-28 14:49 ` Kirill Tkhai
2018-03-21 13:22 ` [PATCH 07/10] list_lru: Pass lru " Kirill Tkhai
2018-03-21 13:22 ` [PATCH 08/10] mm: Set bit in memcg shrinker bitmap on first list_lru item apearance Kirill Tkhai
2018-03-24 19:45 ` Vladimir Davydov
2018-03-26 15:31 ` Kirill Tkhai
2018-03-21 13:22 ` [PATCH 09/10] mm: Iterate only over charged shrinkers during memcg shrink_slab() Kirill Tkhai
2018-03-24 20:11 ` Vladimir Davydov
2018-03-26 15:33 ` Kirill Tkhai
2018-03-21 13:23 ` Kirill Tkhai [this message]
2018-03-24 20:33 ` [PATCH 10/10] mm: Clear shrinker bit if there are no objects related to memcg Vladimir Davydov
2018-03-26 15:37 ` Kirill Tkhai
2018-03-21 13:23 ` [PATCH 00/10] Improve shrink_slab() scalability (old complexity was O(n^2), new is O(n)) Kirill Tkhai
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=152163858159.21546.2876185232270486710.stgit@localhost.localdomain \
--to=ktkhai@virtuozzo.com \
--cc=akpm@linux-foundation.org \
--cc=chris@chris-wilson.co.uk \
--cc=gregkh@linuxfoundation.org \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=hillf.zj@alibaba-inc.com \
--cc=jbacik@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux@roeck-us.net \
--cc=longman@redhat.com \
--cc=mgorman@techsingularity.net \
--cc=mhocko@kernel.org \
--cc=minchan@kernel.org \
--cc=mka@chromium.org \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=pombredanne@nexb.com \
--cc=sfr@canb.auug.org.au \
--cc=shakeelb@google.com \
--cc=stummala@codeaurora.org \
--cc=tglx@linutronix.de \
--cc=vdavydov.dev@gmail.com \
--cc=viro@zeniv.linux.org.uk \
--cc=willy@infradead.org \
--cc=ying.huang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).