The patch titled mm: batch activate_page() to reduce lock contention has been removed from the -mm tree. Its filename was mm-batch-activate_page-to-reduce-lock-contention.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm: batch activate_page() to reduce lock contention From: Shaohua Li <shaohua.li@xxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx: coding-style fixes] Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx> Cc: Minchan Kim <minchan.kim@xxxxxxxxx> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/internal.h | 9 ++++ mm/swap.c | 90 ++++++++++++++++++++++++++++++++++++++++++------ mm/vmscan.c | 6 ++- 3 files changed, 92 insertions(+), 13 deletions(-) diff -puN mm/internal.h~mm-batch-activate_page-to-reduce-lock-contention mm/internal.h --- a/mm/internal.h~mm-batch-activate_page-to-reduce-lock-contention +++ a/mm/internal.h @@ -39,6 +39,15 @@ static inline void __put_page(struct pag extern unsigned long highest_memmap_pfn; +#ifdef CONFIG_SMP +extern int putback_active_lru_page(struct zone *zone, struct page *page); +#else +static inline int putback_active_lru_page(struct zone *zone, struct page *page) +{ + return 0; +} +#endif + /* * in mm/vmscan.c: */ diff -puN mm/swap.c~mm-batch-activate_page-to-reduce-lock-contention mm/swap.c --- a/mm/swap.c~mm-batch-activate_page-to-reduce-lock-contention +++ a/mm/swap.c @@ -271,27 +271,94 @@ static void update_page_reclaim_stat(str } /* - * FIXME: speed this up? + * A page will go to active list either by activate_page or putback_lru_page. + * In the activate_page case, the page hasn't active bit set. The page might + * not in LRU list because it's isolated before it gets a chance to be moved to + * active list. The window is small because pagevec just stores several pages. + * For such case, we do nothing for such page. + * In the putback_lru_page case, the page isn't in lru list but has active + * bit set */ -void activate_page(struct page *page) +static void __activate_page(struct page *page, void *arg) { struct zone *zone = page_zone(page); + int file = page_is_file_cache(page); + int lru = page_lru_base_type(page); + bool putback = !PageLRU(page); + + /* The page is isolated before it's moved to active list */ + if (!PageLRU(page) && !PageActive(page)) + return; + if ((PageLRU(page) && PageActive(page)) || PageUnevictable(page)) + return; - 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); + if (!putback) del_page_from_lru_list(zone, page, lru); + else + SetPageLRU(page); - SetPageActive(page); - lru += LRU_ACTIVE; - add_page_to_lru_list(zone, page, lru); - __count_vm_event(PGACTIVATE); + SetPageActive(page); + lru += LRU_ACTIVE; + add_page_to_lru_list(zone, page, lru); + + if (putback) + return; + __count_vm_event(PGACTIVATE); + 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); - update_page_reclaim_stat(zone, page, file, 1); + page_cache_get(page); + if (!pagevec_add(pvec, page)) + pagevec_lru_move_fn(pvec, __activate_page, NULL); + put_cpu_var(activate_page_pvecs); } +} + +/* Caller should hold zone->lru_lock */ +int putback_active_lru_page(struct zone *zone, struct page *page) +{ + struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); + + if (!pagevec_add(pvec, page)) { + spin_unlock_irq(&zone->lru_lock); + pagevec_lru_move_fn(pvec, __activate_page, NULL); + spin_lock_irq(&zone->lru_lock); + } + put_cpu_var(activate_page_pvecs); + return 1; +} + +#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); + if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) + __activate_page(page, NULL); spin_unlock_irq(&zone->lru_lock); } +#endif /* * Mark a page as having seen activity. @@ -390,6 +457,7 @@ static void drain_cpu_pagevecs(int cpu) pagevec_move_tail(pvec); local_irq_restore(flags); } + activate_page_drain(cpu); } void lru_add_drain(void) diff -puN mm/vmscan.c~mm-batch-activate_page-to-reduce-lock-contention mm/vmscan.c --- a/mm/vmscan.c~mm-batch-activate_page-to-reduce-lock-contention +++ a/mm/vmscan.c @@ -1271,14 +1271,16 @@ putback_lru_pages(struct zone *zone, str spin_lock_irq(&zone->lru_lock); continue; } - SetPageLRU(page); lru = page_lru(page); - add_page_to_lru_list(zone, page, lru); if (is_active_lru(lru)) { int file = is_file_lru(lru); int numpages = hpage_nr_pages(page); reclaim_stat->recent_rotated[file] += numpages; + if (putback_active_lru_page(zone, page)) + continue; } + SetPageLRU(page); + add_page_to_lru_list(zone, page, lru); if (!pagevec_add(&pvec, page)) { spin_unlock_irq(&zone->lru_lock); __pagevec_release(&pvec); _ Patches currently in -mm which might be from shaohua.li@xxxxxxxxx are origin.patch writeback-io-less-balance_dirty_pages.patch writeback-consolidate-variable-names-in-balance_dirty_pages.patch writeback-per-task-rate-limit-on-balance_dirty_pages.patch writeback-per-task-rate-limit-on-balance_dirty_pages-fix.patch writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls.patch writeback-account-per-bdi-accumulated-written-pages.patch writeback-bdi-write-bandwidth-estimation.patch writeback-bdi-write-bandwidth-estimation-fix.patch writeback-show-bdi-write-bandwidth-in-debugfs.patch writeback-quit-throttling-when-bdi-dirty-pages-dropped-low.patch writeback-reduce-per-bdi-dirty-threshold-ramp-up-time.patch writeback-make-reasonable-gap-between-the-dirty-background-thresholds.patch writeback-scale-down-max-throttle-bandwidth-on-concurrent-dirtiers.patch writeback-add-trace-event-for-balance_dirty_pages.patch writeback-make-nr_to_write-a-per-file-limit.patch writeback-make-nr_to_write-a-per-file-limit-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html