From: KOSAKI Motohiro Date: Tue, 15 Dec 2009 01:59:12 +0000 (-0800) Subject: vmscan: kill hibernation specific reclaim logic and unify it X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7b51755c3b38483b574d363d5ee587283c3f7999;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git vmscan: kill hibernation specific reclaim logic and unify it shrink_all_zone() was introduced by commit d6277db4ab (swsusp: rework memory shrinker) for hibernate performance improvement. and sc.swap_cluster_max was introduced by commit a06fe4d307 (Speed freeing memory for suspend). commit a06fe4d307 said Without the patch: Freed 14600 pages in 1749 jiffies = 32.61 MB/s (Anomolous!) Freed 88563 pages in 14719 jiffies = 23.50 MB/s Freed 205734 pages in 32389 jiffies = 24.81 MB/s With the patch: Freed 68252 pages in 496 jiffies = 537.52 MB/s Freed 116464 pages in 569 jiffies = 798.54 MB/s Freed 209699 pages in 705 jiffies = 1161.89 MB/s At that time, their patch was pretty worth. However, Modern Hardware trend and recent VM improvement broke its worth. From several reason, I think we should remove shrink_all_zones() at all. detail: 1) Old days, shrink_zone()'s slowness was mainly caused by stupid io-throttle at no i/o congestion. but current shrink_zone() is sane, not slow. 2) shrink_all_zone() try to shrink all pages at a time. but it doesn't works fine on numa system. example) System has 4GB memory and each node have 2GB. and hibernate need 1GB. optimal) steal 500MB from each node. shrink_all_zones) steal 1GB from node-0. Oh, Cache balancing logic was broken. ;) Unfortunately, Desktop system moved ahead NUMA at nowadays. (Side note, if hibernate require 2GB, shrink_all_zones() never success on above machine) 3) if the node has several I/O flighting pages, shrink_all_zones() makes pretty bad result. schenario) hibernate need 1GB 1) shrink_all_zones() try to reclaim 1GB from Node-0 2) but it only reclaimed 990MB 3) stupidly, shrink_all_zones() try to reclaim 1GB from Node-1 4) it reclaimed 990MB Oh, well. it reclaimed twice much than required. In the other hand, current shrink_zone() has sane baling out logic. then, it doesn't make overkill reclaim. then, we lost shrink_zones()'s risk. 4) SplitLRU VM always keep active/inactive ratio very carefully. inactive list only shrinking break its assumption. it makes unnecessary OOM risk. it obviously suboptimal. Now, shrink_all_memory() is only the wrapper function of do_try_to_free_pages(). it bring good reviewability and debuggability, and solve above problems. side note: Reclaim logic unificication makes two good side effect. - Fix recursive reclaim bug on shrink_all_memory(). it did forgot to use PF_MEMALLOC. it mean the system be able to stuck into deadlock. - Now, shrink_all_memory() got lockdep awareness. it bring good debuggability. Signed-off-by: KOSAKI Motohiro Reviewed-by: Rik van Riel Acked-by: Rafael J. Wysocki Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/vmscan.c b/mm/vmscan.c index 7b0d5c784c7e..63bd521bb229 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -58,6 +58,8 @@ struct scan_control { /* How many pages shrink_list() should reclaim */ unsigned long nr_to_reclaim; + unsigned long hibernation_mode; + /* This context's GFP mask */ gfp_t gfp_mask; @@ -1796,7 +1798,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, } /* Take a nap, wait for some writeback to complete */ - if (sc->nr_scanned && priority < DEF_PRIORITY - 2) + if (!sc->hibernation_mode && sc->nr_scanned && + priority < DEF_PRIORITY - 2) congestion_wait(BLK_RW_ASYNC, HZ/10); } /* top priority shrink_zones still had more to do? don't OOM, then */ @@ -2336,148 +2339,44 @@ unsigned long zone_reclaimable_pages(struct zone *zone) #ifdef CONFIG_HIBERNATION /* - * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages - * from LRU lists system-wide, for given pass and priority. - * - * For pass > 3 we also try to shrink the LRU lists that contain a few pages - */ -static void shrink_all_zones(unsigned long nr_pages, int prio, - int pass, struct scan_control *sc) -{ - struct zone *zone; - unsigned long nr_reclaimed = 0; - struct zone_reclaim_stat *reclaim_stat; - - for_each_populated_zone(zone) { - enum lru_list l; - - if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY) - continue; - - for_each_evictable_lru(l) { - enum zone_stat_item ls = NR_LRU_BASE + l; - unsigned long lru_pages = zone_page_state(zone, ls); - - /* For pass = 0, we don't shrink the active list */ - if (pass == 0 && (l == LRU_ACTIVE_ANON || - l == LRU_ACTIVE_FILE)) - continue; - - reclaim_stat = get_reclaim_stat(zone, sc); - reclaim_stat->nr_saved_scan[l] += - (lru_pages >> prio) + 1; - if (reclaim_stat->nr_saved_scan[l] - >= nr_pages || pass > 3) { - unsigned long nr_to_scan; - - reclaim_stat->nr_saved_scan[l] = 0; - nr_to_scan = min(nr_pages, lru_pages); - nr_reclaimed += shrink_list(l, nr_to_scan, zone, - sc, prio); - if (nr_reclaimed >= nr_pages) { - sc->nr_reclaimed += nr_reclaimed; - return; - } - } - } - } - sc->nr_reclaimed += nr_reclaimed; -} - -/* - * Try to free `nr_pages' of memory, system-wide, and return the number of + * Try to free `nr_to_reclaim' of memory, system-wide, and return the number of * freed pages. * * Rather than trying to age LRUs the aim is to preserve the overall * LRU order by reclaiming preferentially * inactive > active > active referenced > active mapped */ -unsigned long shrink_all_memory(unsigned long nr_pages) +unsigned long shrink_all_memory(unsigned long nr_to_reclaim) { - unsigned long lru_pages, nr_slab; - int pass; struct reclaim_state reclaim_state; struct scan_control sc = { - .gfp_mask = GFP_KERNEL, - .may_unmap = 0, + .gfp_mask = GFP_HIGHUSER_MOVABLE, + .may_swap = 1, + .may_unmap = 1, .may_writepage = 1, + .swap_cluster_max = SWAP_CLUSTER_MAX, + .nr_to_reclaim = nr_to_reclaim, + .hibernation_mode = 1, + .swappiness = vm_swappiness, + .order = 0, .isolate_pages = isolate_pages_global, - .nr_reclaimed = 0, }; + struct zonelist * zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); + struct task_struct *p = current; + unsigned long nr_reclaimed; - current->reclaim_state = &reclaim_state; - - lru_pages = global_reclaimable_pages(); - nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); - /* If slab caches are huge, it's better to hit them first */ - while (nr_slab >= lru_pages) { - reclaim_state.reclaimed_slab = 0; - shrink_slab(nr_pages, sc.gfp_mask, lru_pages); - if (!reclaim_state.reclaimed_slab) - break; - - sc.nr_reclaimed += reclaim_state.reclaimed_slab; - if (sc.nr_reclaimed >= nr_pages) - goto out; - - nr_slab -= reclaim_state.reclaimed_slab; - } - - /* - * We try to shrink LRUs in 5 passes: - * 0 = Reclaim from inactive_list only - * 1 = Reclaim from active list but don't reclaim mapped - * 2 = 2nd pass of type 1 - * 3 = Reclaim mapped (normal reclaim) - * 4 = 2nd pass of type 3 - */ - for (pass = 0; pass < 5; pass++) { - int prio; - - /* Force reclaiming mapped pages in the passes #3 and #4 */ - if (pass > 2) - sc.may_unmap = 1; - - for (prio = DEF_PRIORITY; prio >= 0; prio--) { - unsigned long nr_to_scan = nr_pages - sc.nr_reclaimed; - - sc.nr_scanned = 0; - sc.swap_cluster_max = nr_to_scan; - shrink_all_zones(nr_to_scan, prio, pass, &sc); - if (sc.nr_reclaimed >= nr_pages) - goto out; - - reclaim_state.reclaimed_slab = 0; - shrink_slab(sc.nr_scanned, sc.gfp_mask, - global_reclaimable_pages()); - sc.nr_reclaimed += reclaim_state.reclaimed_slab; - if (sc.nr_reclaimed >= nr_pages) - goto out; - - if (sc.nr_scanned && prio < DEF_PRIORITY - 2) - congestion_wait(BLK_RW_ASYNC, HZ / 10); - } - } - - /* - * If sc.nr_reclaimed = 0, we could not shrink LRUs, but there may be - * something in slab caches - */ - if (!sc.nr_reclaimed) { - do { - reclaim_state.reclaimed_slab = 0; - shrink_slab(nr_pages, sc.gfp_mask, - global_reclaimable_pages()); - sc.nr_reclaimed += reclaim_state.reclaimed_slab; - } while (sc.nr_reclaimed < nr_pages && - reclaim_state.reclaimed_slab > 0); - } + p->flags |= PF_MEMALLOC; + lockdep_set_current_reclaim_state(sc.gfp_mask); + reclaim_state.reclaimed_slab = 0; + p->reclaim_state = &reclaim_state; + nr_reclaimed = do_try_to_free_pages(zonelist, &sc); -out: - current->reclaim_state = NULL; + p->reclaim_state = NULL; + lockdep_clear_current_reclaim_state(); + p->flags &= ~PF_MEMALLOC; - return sc.nr_reclaimed; + return nr_reclaimed; } #endif /* CONFIG_HIBERNATION */