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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. 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. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Shaohua Li <shaohua.li@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Shaohua Li
Linus Torvalds
parent
d8505dee1a
commit
744ed14427
3 changed files with 94 additions and 15 deletions
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@ -39,6 +39,15 @@ static inline void __put_page(struct page *page)
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extern unsigned long highest_memmap_pfn;
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#ifdef CONFIG_SMP
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extern int putback_active_lru_page(struct zone *zone, struct page *page);
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#else
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static inline int putback_active_lru_page(struct zone *zone, struct page *page)
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{
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return 0;
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}
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#endif
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/*
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* in mm/vmscan.c:
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*/
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94
mm/swap.c
94
mm/swap.c
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@ -271,27 +271,94 @@ static void update_page_reclaim_stat(struct zone *zone, struct page *page,
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}
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/*
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* FIXME: speed this up?
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* A page will go to active list either by activate_page or putback_lru_page.
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* In the activate_page case, the page hasn't active bit set. The page might
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* not in LRU list because it's isolated before it gets a chance to be moved to
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* active list. The window is small because pagevec just stores several pages.
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* For such case, we do nothing for such page.
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* In the putback_lru_page case, the page isn't in lru list but has active
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* bit set
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*/
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static void __activate_page(struct page *page, void *arg)
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{
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struct zone *zone = page_zone(page);
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int file = page_is_file_cache(page);
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int lru = page_lru_base_type(page);
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bool putback = !PageLRU(page);
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/* The page is isolated before it's moved to active list */
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if (!PageLRU(page) && !PageActive(page))
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return;
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if ((PageLRU(page) && PageActive(page)) || PageUnevictable(page))
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return;
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if (!putback)
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del_page_from_lru_list(zone, page, lru);
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else
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SetPageLRU(page);
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SetPageActive(page);
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lru += LRU_ACTIVE;
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add_page_to_lru_list(zone, page, lru);
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if (putback)
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return;
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__count_vm_event(PGACTIVATE);
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update_page_reclaim_stat(zone, page, file, 1);
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}
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#ifdef CONFIG_SMP
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static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
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static void activate_page_drain(int cpu)
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{
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struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
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if (pagevec_count(pvec))
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pagevec_lru_move_fn(pvec, __activate_page, NULL);
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}
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void activate_page(struct page *page)
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{
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
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struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
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page_cache_get(page);
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if (!pagevec_add(pvec, page))
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pagevec_lru_move_fn(pvec, __activate_page, NULL);
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put_cpu_var(activate_page_pvecs);
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}
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}
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/* Caller should hold zone->lru_lock */
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int putback_active_lru_page(struct zone *zone, struct page *page)
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{
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struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
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if (!pagevec_add(pvec, page)) {
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spin_unlock_irq(&zone->lru_lock);
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pagevec_lru_move_fn(pvec, __activate_page, NULL);
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spin_lock_irq(&zone->lru_lock);
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}
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put_cpu_var(activate_page_pvecs);
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return 1;
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}
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#else
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static inline void activate_page_drain(int cpu)
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{
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}
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void activate_page(struct page *page)
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{
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struct zone *zone = page_zone(page);
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spin_lock_irq(&zone->lru_lock);
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
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int file = page_is_file_cache(page);
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int lru = page_lru_base_type(page);
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del_page_from_lru_list(zone, page, lru);
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SetPageActive(page);
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lru += LRU_ACTIVE;
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add_page_to_lru_list(zone, page, lru);
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__count_vm_event(PGACTIVATE);
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update_page_reclaim_stat(zone, page, file, 1);
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}
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page))
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__activate_page(page, NULL);
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spin_unlock_irq(&zone->lru_lock);
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}
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#endif
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/*
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* Mark a page as having seen activity.
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@ -390,6 +457,7 @@ static void drain_cpu_pagevecs(int cpu)
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pagevec_move_tail(pvec);
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local_irq_restore(flags);
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}
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activate_page_drain(cpu);
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}
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void lru_add_drain(void)
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@ -1271,14 +1271,16 @@ putback_lru_pages(struct zone *zone, struct scan_control *sc,
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spin_lock_irq(&zone->lru_lock);
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continue;
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}
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SetPageLRU(page);
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lru = page_lru(page);
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add_page_to_lru_list(zone, page, lru);
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if (is_active_lru(lru)) {
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int file = is_file_lru(lru);
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int numpages = hpage_nr_pages(page);
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reclaim_stat->recent_rotated[file] += numpages;
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if (putback_active_lru_page(zone, page))
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continue;
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}
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SetPageLRU(page);
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add_page_to_lru_list(zone, page, lru);
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if (!pagevec_add(&pvec, page)) {
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spin_unlock_irq(&zone->lru_lock);
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__pagevec_release(&pvec);
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