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author | Shaohua Li <shaohua.li@intel.com> | 2011-05-24 17:12:55 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-25 08:39:37 -0700 |
commit | eb709b0d062efd653a61183af8e27b2711c3cf5c (patch) | |
tree | ea0b4139854c2e713acab7ac679fa368ef9187ef /mm | |
parent | f68aa5b445fd00b67588ade611a4efb1a34dadb4 (diff) | |
download | op-kernel-dev-eb709b0d062efd653a61183af8e27b2711c3cf5c.zip op-kernel-dev-eb709b0d062efd653a61183af8e27b2711c3cf5c.tar.gz |
mm: batch activate_page() to reduce lock contention
The zone->lru_lock is heavily contented in workload where activate_page()
is frequently used. We could do batch activate_page() to reduce the lock
contention. The batched pages will be added into zone list when the pool
is full or page reclaim is trying to drain them.
For example, in a 4 socket 64 CPU system, create a sparse file and 64
processes, processes shared map to the file. Each process read access the
whole file and then exit. The process exit will do unmap_vmas() and cause
a lot of activate_page() call. In such workload, we saw about 58% total
time reduction with below patch. Other workloads with a lot of
activate_page also benefits a lot too.
Andrew Morton suggested activate_page() and putback_lru_pages() should
follow the same path to active pages, but this is hard to implement (see
commit 7a608572a282a ("Revert "mm: batch activate_page() to reduce lock
contention")). On the other hand, do we really need putback_lru_pages()
to follow the same path? I tested several FIO/FFSB benchmark (about 20
scripts for each benchmark) in 3 machines here from 2 sockets to 4
sockets. My test doesn't show anything significant with/without below
patch (there is slight difference but mostly some noise which we found
even without below patch before). Below patch basically returns to the
same as my first post.
I tested some microbenchmarks:
case-anon-cow-rand-mt 0.58%
case-anon-cow-rand -3.30%
case-anon-cow-seq-mt -0.51%
case-anon-cow-seq -5.68%
case-anon-r-rand-mt 0.23%
case-anon-r-rand 0.81%
case-anon-r-seq-mt -0.71%
case-anon-r-seq -1.99%
case-anon-rx-rand-mt 2.11%
case-anon-rx-seq-mt 3.46%
case-anon-w-rand-mt -0.03%
case-anon-w-rand -0.50%
case-anon-w-seq-mt -1.08%
case-anon-w-seq -0.12%
case-anon-wx-rand-mt -5.02%
case-anon-wx-seq-mt -1.43%
case-fork 1.65%
case-fork-sleep -0.07%
case-fork-withmem 1.39%
case-hugetlb -0.59%
case-lru-file-mmap-read-mt -0.54%
case-lru-file-mmap-read 0.61%
case-lru-file-mmap-read-rand -2.24%
case-lru-file-readonce -0.64%
case-lru-file-readtwice -11.69%
case-lru-memcg -1.35%
case-mmap-pread-rand-mt 1.88%
case-mmap-pread-rand -15.26%
case-mmap-pread-seq-mt 0.89%
case-mmap-pread-seq -69.72%
case-mmap-xread-rand-mt 0.71%
case-mmap-xread-seq-mt 0.38%
The most significent are:
case-lru-file-readtwice -11.69%
case-mmap-pread-rand -15.26%
case-mmap-pread-seq -69.72%
which use activate_page a lot. others are basically variations because
each run has slightly difference.
In UP case, 'size mm/swap.o'
before the two patches:
text data bss dec hex filename
6466 896 4 7366 1cc6 mm/swap.o
after the two patches:
text data bss dec hex filename
6343 896 4 7243 1c4b mm/swap.o
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/swap.c | 45 |
1 files changed, 40 insertions, 5 deletions
@@ -272,14 +272,10 @@ static void update_page_reclaim_stat(struct zone *zone, struct page *page, memcg_reclaim_stat->recent_rotated[file]++; } -/* - * FIXME: speed this up? - */ -void activate_page(struct page *page) +static void __activate_page(struct page *page, void *arg) { struct zone *zone = page_zone(page); - spin_lock_irq(&zone->lru_lock); if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { int file = page_is_file_cache(page); int lru = page_lru_base_type(page); @@ -292,8 +288,45 @@ void activate_page(struct page *page) update_page_reclaim_stat(zone, page, file, 1); } +} + +#ifdef CONFIG_SMP +static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); + +static void activate_page_drain(int cpu) +{ + struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); + + if (pagevec_count(pvec)) + pagevec_lru_move_fn(pvec, __activate_page, NULL); +} + +void activate_page(struct page *page) +{ + if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { + struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); + + page_cache_get(page); + if (!pagevec_add(pvec, page)) + pagevec_lru_move_fn(pvec, __activate_page, NULL); + put_cpu_var(activate_page_pvecs); + } +} + +#else +static inline void activate_page_drain(int cpu) +{ +} + +void activate_page(struct page *page) +{ + struct zone *zone = page_zone(page); + + spin_lock_irq(&zone->lru_lock); + __activate_page(page, NULL); spin_unlock_irq(&zone->lru_lock); } +#endif /* * Mark a page as having seen activity. @@ -464,6 +497,8 @@ static void drain_cpu_pagevecs(int cpu) pvec = &per_cpu(lru_deactivate_pvecs, cpu); if (pagevec_count(pvec)) pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); + + activate_page_drain(cpu); } /** |