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| author | Johannes Weiner | 2016-07-29 00:45:10 +0200 |
|---|---|---|
| committer | Linus Torvalds | 2016-07-29 01:07:41 +0200 |
| commit | 55779ec759ccc3c12b917b3712a7716e1140c652 (patch) | |
| tree | d119d51e0c82b2535f0a6519799f5387b94192f6 /include/linux/mm.h | |
| parent | mm: update the comment in __isolate_free_page (diff) | |
| download | kernel-qcow2-linux-55779ec759ccc3c12b917b3712a7716e1140c652.tar.gz kernel-qcow2-linux-55779ec759ccc3c12b917b3712a7716e1140c652.tar.xz kernel-qcow2-linux-55779ec759ccc3c12b917b3712a7716e1140c652.zip | |
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/linux/mm.h')
| -rw-r--r-- | include/linux/mm.h | 10 |
1 files changed, 10 insertions, 0 deletions
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 /* |