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authorJohannes Weiner <hannes@cmpxchg.org>2016-07-29 01:45:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-29 02:07:41 +0300
commit55779ec759ccc3c12b917b3712a7716e1140c652 (patch)
treed119d51e0c82b2535f0a6519799f5387b94192f6 /include
parent400bc7fd4fa7d33c96d836e6b65eeed246f1959a (diff)
downloadlinux-55779ec759ccc3c12b917b3712a7716e1140c652.tar.xz
mm: fix vm-scalability regression in cgroup-aware workingset code
Commit 23047a96d7cf ("mm: workingset: per-cgroup cache thrash detection") added a page->mem_cgroup lookup to the cache eviction, refault, and activation paths, as well as locking to the activation path, and the vm-scalability tests showed a regression of -23%. While the test in question is an artificial worst-case scenario that doesn't occur in real workloads - reading two sparse files in parallel at full CPU speed just to hammer the LRU paths - there is still some optimizations that can be done in those paths. Inline the lookup functions to eliminate calls. Also, page->mem_cgroup doesn't need to be stabilized when counting an activation; we merely need to hold the RCU lock to prevent the memcg from being freed. This cuts down on overhead quite a bit: 23047a96d7cfcfca 063f6715e77a7be5770d6081fe ---------------- -------------------------- %stddev %change %stddev \ | \ 21621405 +- 0% +11.3% 24069657 +- 2% vm-scalability.throughput [linux@roeck-us.net: drop unnecessary include file] [hannes@cmpxchg.org: add WARN_ON_ONCE()s] Link: http://lkml.kernel.org/r/20160707194024.GA26580@cmpxchg.org Link: http://lkml.kernel.org/r/20160624175101.GA3024@cmpxchg.org Reported-by: Ye Xiaolong <xiaolong.ye@intel.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/memcontrol.h43
-rw-r--r--include/linux/mm.h10
2 files changed, 52 insertions, 1 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 71aff733a497..1c4df4420258 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -314,7 +314,48 @@ void mem_cgroup_uncharge_list(struct list_head *page_list);
void mem_cgroup_migrate(struct page *oldpage, struct page *newpage);
-struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
+static inline struct mem_cgroup_per_zone *
+mem_cgroup_zone_zoneinfo(struct mem_cgroup *memcg, struct zone *zone)
+{
+ int nid = zone_to_nid(zone);
+ int zid = zone_idx(zone);
+
+ return &memcg->nodeinfo[nid]->zoneinfo[zid];
+}
+
+/**
+ * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
+ * @zone: zone of the wanted lruvec
+ * @memcg: memcg of the wanted lruvec
+ *
+ * Returns the lru list vector holding pages for the given @zone and
+ * @mem. This can be the global zone lruvec, if the memory controller
+ * is disabled.
+ */
+static inline struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
+ struct mem_cgroup *memcg)
+{
+ struct mem_cgroup_per_zone *mz;
+ struct lruvec *lruvec;
+
+ if (mem_cgroup_disabled()) {
+ lruvec = &zone->lruvec;
+ goto out;
+ }
+
+ mz = mem_cgroup_zone_zoneinfo(memcg, zone);
+ lruvec = &mz->lruvec;
+out:
+ /*
+ * Since a node can be onlined after the mem_cgroup was created,
+ * we have to be prepared to initialize lruvec->zone here;
+ * and if offlined then reonlined, we need to reinitialize it.
+ */
+ if (unlikely(lruvec->zone != zone))
+ lruvec->zone = zone;
+ return lruvec;
+}
+
struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c606fe4f9a7f..97065e1f0237 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -973,11 +973,21 @@ static inline struct mem_cgroup *page_memcg(struct page *page)
{
return page->mem_cgroup;
}
+static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return READ_ONCE(page->mem_cgroup);
+}
#else
static inline struct mem_cgroup *page_memcg(struct page *page)
{
return NULL;
}
+static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return NULL;
+}
#endif
/*