diff options
| -rw-r--r-- | include/linux/compaction.h | 14 | ||||
| -rw-r--r-- | include/linux/kernel.h | 7 | ||||
| -rw-r--r-- | mm/compaction.c | 89 | ||||
| -rw-r--r-- | mm/migrate.c | 17 | ||||
| -rw-r--r-- | mm/page_alloc.c | 16 | ||||
| -rw-r--r-- | mm/vmscan.c | 102 |
6 files changed, 196 insertions, 49 deletions
diff --git a/include/linux/compaction.h b/include/linux/compaction.h index 5ac51552d908..2592883d862d 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -22,6 +22,9 @@ extern int sysctl_extfrag_handler(struct ctl_table *table, int write, extern int fragmentation_index(struct zone *zone, unsigned int order); extern unsigned long try_to_compact_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *mask); +extern unsigned long compaction_suitable(struct zone *zone, int order); +extern unsigned long compact_zone_order(struct zone *zone, int order, + gfp_t gfp_mask); /* Do not skip compaction more than 64 times */ #define COMPACT_MAX_DEFER_SHIFT 6 @@ -59,6 +62,17 @@ static inline unsigned long try_to_compact_pages(struct zonelist *zonelist, return COMPACT_CONTINUE; } +static inline unsigned long compaction_suitable(struct zone *zone, int order) +{ + return COMPACT_SKIPPED; +} + +static inline unsigned long compact_zone_order(struct zone *zone, int order, + gfp_t gfp_mask) +{ + return 0; +} + static inline void defer_compaction(struct zone *zone) { } diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 57dac7022b63..5a9d9059520b 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -600,6 +600,13 @@ struct sysinfo { #define NUMA_BUILD 0 #endif +/* This helps us avoid #ifdef CONFIG_COMPACTION */ +#ifdef CONFIG_COMPACTION +#define COMPACTION_BUILD 1 +#else +#define COMPACTION_BUILD 0 +#endif + /* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */ #ifdef CONFIG_FTRACE_MCOUNT_RECORD # define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD diff --git a/mm/compaction.c b/mm/compaction.c index 20011a850fef..8fe917ec7c11 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -384,10 +384,62 @@ static int compact_finished(struct zone *zone, return COMPACT_CONTINUE; } +/* + * compaction_suitable: Is this suitable to run compaction on this zone now? + * Returns + * COMPACT_SKIPPED - If there are too few free pages for compaction + * COMPACT_PARTIAL - If the allocation would succeed without compaction + * COMPACT_CONTINUE - If compaction should run now + */ +unsigned long compaction_suitable(struct zone *zone, int order) +{ + int fragindex; + unsigned long watermark; + + /* + * Watermarks for order-0 must be met for compaction. Note the 2UL. + * This is because during migration, copies of pages need to be + * allocated and for a short time, the footprint is higher + */ + watermark = low_wmark_pages(zone) + (2UL << order); + if (!zone_watermark_ok(zone, 0, watermark, 0, 0)) + return COMPACT_SKIPPED; + + /* + * fragmentation index determines if allocation failures are due to + * low memory or external fragmentation + * + * index of -1 implies allocations might succeed dependingon watermarks + * index towards 0 implies failure is due to lack of memory + * index towards 1000 implies failure is due to fragmentation + * + * Only compact if a failure would be due to fragmentation. + */ + fragindex = fragmentation_index(zone, order); + if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) + return COMPACT_SKIPPED; + + if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) + return COMPACT_PARTIAL; + + return COMPACT_CONTINUE; +} + static int compact_zone(struct zone *zone, struct compact_control *cc) { int ret; + ret = compaction_suitable(zone, cc->order); + switch (ret) { + case COMPACT_PARTIAL: + case COMPACT_SKIPPED: + /* Compaction is likely to fail */ + return ret; + case COMPACT_CONTINUE: + /* Fall through to compaction */ + ; + } + /* Setup to move all movable pages to the end of the zone */ cc->migrate_pfn = zone->zone_start_pfn; cc->free_pfn = cc->migrate_pfn + zone->spanned_pages; @@ -429,7 +481,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) return ret; } -static unsigned long compact_zone_order(struct zone *zone, +unsigned long compact_zone_order(struct zone *zone, int order, gfp_t gfp_mask) { struct compact_control cc = { @@ -462,7 +514,6 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist, enum zone_type high_zoneidx = gfp_zone(gfp_mask); int may_enter_fs = gfp_mask & __GFP_FS; int may_perform_io = gfp_mask & __GFP_IO; - unsigned long watermark; struct zoneref *z; struct zone *zone; int rc = COMPACT_SKIPPED; @@ -480,43 +531,13 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist, /* Compact each zone in the list */ for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx, nodemask) { - int fragindex; int status; - /* - * Watermarks for order-0 must be met for compaction. Note - * the 2UL. This is because during migration, copies of - * pages need to be allocated and for a short time, the - * footprint is higher - */ - watermark = low_wmark_pages(zone) + (2UL << order); - if (!zone_watermark_ok(zone, 0, watermark, 0, 0)) - continue; - - /* - * fragmentation index determines if allocation failures are - * due to low memory or external fragmentation - * - * index of -1 implies allocations might succeed depending - * on watermarks - * index towards 0 implies failure is due to lack of memory - * index towards 1000 implies failure is due to fragmentation - * - * Only compact if a failure would be due to fragmentation. - */ - fragindex = fragmentation_index(zone, order); - if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) - continue; - - if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) { - rc = COMPACT_PARTIAL; - break; - } - status = compact_zone_order(zone, order, gfp_mask); rc = max(status, rc); - if (zone_watermark_ok(zone, order, watermark, 0, 0)) + /* If a normal allocation would succeed, stop compacting */ + if (zone_watermark_ok(zone, order, low_wmark_pages(zone), 0, 0)) break; } diff --git a/mm/migrate.c b/mm/migrate.c index 6ae8a66a7045..94875b265928 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -639,6 +639,23 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, if (!trylock_page(page)) { if (!force) goto move_newpage; + + /* + * It's not safe for direct compaction to call lock_page. + * For example, during page readahead pages are added locked + * to the LRU. Later, when the IO completes the pages are + * marked uptodate and unlocked. However, the queueing + * could be merging multiple pages for one bio (e.g. + * mpage_readpages). If an allocation happens for the + * second or third page, the process can end up locking + * the same page twice and deadlocking. Rather than + * trying to be clever about what pages can be locked, + * avoid the use of lock_page for direct compaction + * altogether. + */ + if (current->flags & PF_MEMALLOC) + goto move_newpage; + lock_page(page); } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 22a1bb7723e4..03a66a31bfcd 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1815,12 +1815,15 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, int migratetype, unsigned long *did_some_progress) { struct page *page; + struct task_struct *tsk = current; if (!order || compaction_deferred(preferred_zone)) return NULL; + tsk->flags |= PF_MEMALLOC; *did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask, nodemask); + tsk->flags &= ~PF_MEMALLOC; if (*did_some_progress != COMPACT_SKIPPED) { /* Page migration frees to the PCP lists but we want merging */ @@ -2121,6 +2124,19 @@ rebalance: /* Wait for some write requests to complete then retry */ wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50); goto rebalance; + } else { + /* + * High-order allocations do not necessarily loop after + * direct reclaim and reclaim/compaction depends on compaction + * being called after reclaim so call directly if necessary + */ + page = __alloc_pages_direct_compact(gfp_mask, order, + zonelist, high_zoneidx, + nodemask, + alloc_flags, preferred_zone, + migratetype, &did_some_progress); + if (page) + goto got_pg; } nopage: diff --git a/mm/vmscan.c b/mm/vmscan.c index 3464312bde07..10ebd74a423c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -32,6 +32,7 @@ #include <linux/topology.h> #include <linux/cpu.h> #include <linux/cpuset.h> +#include <linux/compaction.h> #include <linux/notifier.h> #include <linux/rwsem.h> #include <linux/delay.h> @@ -59,12 +60,15 @@ * LUMPY_MODE_CONTIGRECLAIM: For high-order allocations, take a reference * page from the LRU and reclaim all pages within a * naturally aligned range + * LUMPY_MODE_COMPACTION: For high-order allocations, reclaim a number of + * order-0 pages and then compact the zone */ typedef unsigned __bitwise__ lumpy_mode; #define LUMPY_MODE_SINGLE ((__force lumpy_mode)0x01u) #define LUMPY_MODE_ASYNC ((__force lumpy_mode)0x02u) #define LUMPY_MODE_SYNC ((__force lumpy_mode)0x04u) #define LUMPY_MODE_CONTIGRECLAIM ((__force lumpy_mode)0x08u) +#define LUMPY_MODE_COMPACTION ((__force lumpy_mode)0x10u) struct scan_control { /* Incremented by the number of inactive pages that were scanned */ @@ -286,18 +290,20 @@ static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc, lumpy_mode syncmode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC; /* - * Some reclaim have alredy been failed. No worth to try synchronous - * lumpy reclaim. + * Initially assume we are entering either lumpy reclaim or + * reclaim/compaction.Depending on the order, we will either set the + * sync mode or just reclaim order-0 pages later. */ - if (sync && sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE) - return; + if (COMPACTION_BUILD) + sc->lumpy_reclaim_mode = LUMPY_MODE_COMPACTION; + else + sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM; /* - * If we need a large contiguous chunk of memory, or have - * trouble getting a small set of contiguous pages, we - * will reclaim both active and inactive pages. + * Avoid using lumpy reclaim or reclaim/compaction if possible by + * restricting when its set to either costly allocations or when + * under memory pressure */ - sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM; if (sc->order > PAGE_ALLOC_COSTLY_ORDER) sc->lumpy_reclaim_mode |= syncmode; else if (sc->order && priority < DEF_PRIORITY - 2) @@ -1385,8 +1391,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, if (scanning_global_lru(sc)) { nr_taken = isolate_pages_global(nr_to_scan, &page_list, &nr_scanned, sc->order, - sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ? - ISOLATE_INACTIVE : ISOLATE_BOTH, + sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM ? + ISOLATE_BOTH : ISOLATE_INACTIVE, zone, 0, file); zone->pages_scanned += nr_scanned; if (current_is_kswapd()) @@ -1398,8 +1404,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, } else { nr_taken = mem_cgroup_isolate_pages(nr_to_scan, &page_list, &nr_scanned, sc->order, - sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ? - ISOLATE_INACTIVE : ISOLATE_BOTH, + sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM ? + ISOLATE_BOTH : ISOLATE_INACTIVE, zone, sc->mem_cgroup, 0, file); /* @@ -1815,6 +1821,57 @@ out: } /* + * Reclaim/compaction depends on a number of pages being freed. To avoid + * disruption to the system, a small number of order-0 pages continue to be + * rotated and reclaimed in the normal fashion. However, by the time we get + * back to the allocator and call try_to_compact_zone(), we ensure that + * there are enough free pages for it to be likely successful + */ +static inline bool should_continue_reclaim(struct zone *zone, + unsigned long nr_reclaimed, + unsigned long nr_scanned, + struct scan_control *sc) +{ + unsigned long pages_for_compaction; + unsigned long inactive_lru_pages; + + /* If not in reclaim/compaction mode, stop */ + if (!(sc->lumpy_reclaim_mode & LUMPY_MODE_COMPACTION)) + return false; + + /* + * If we failed to reclaim and have scanned the full list, stop. + * NOTE: Checking just nr_reclaimed would exit reclaim/compaction far + * faster but obviously would be less likely to succeed + * allocation. If this is desirable, use GFP_REPEAT to decide + * if both reclaimed and scanned should be checked or just + * reclaimed + */ + if (!nr_reclaimed && !nr_scanned) + return false; + + /* + * If we have not reclaimed enough pages for compaction and the + * inactive lists are large enough, continue reclaiming + */ + pages_for_compaction = (2UL << sc->order); + inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) + + zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE); + if (sc->nr_reclaimed < pages_for_compaction && + inactive_lru_pages > pages_for_compaction) + return true; + + /* If compaction would go ahead or the allocation would succeed, stop */ + switch (compaction_suitable(zone, sc->order)) { + case COMPACT_PARTIAL: + case COMPACT_CONTINUE: + return false; + default: + return true; + } +} + +/* * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. */ static void shrink_zone(int priority, struct zone *zone, @@ -1823,9 +1880,12 @@ static void shrink_zone(int priority, struct zone *zone, unsigned long nr[NR_LRU_LISTS]; unsigned long nr_to_scan; enum lru_list l; - unsigned long nr_reclaimed = sc->nr_reclaimed; + unsigned long nr_reclaimed; unsigned long nr_to_reclaim = sc->nr_to_reclaim; + unsigned long nr_scanned = sc->nr_scanned; +restart: + nr_reclaimed = 0; get_scan_count(zone, sc, nr, priority); while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || @@ -1851,8 +1911,7 @@ static void shrink_zone(int priority, struct zone *zone, if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) break; } - - sc->nr_reclaimed = nr_reclaimed; + sc->nr_reclaimed += nr_reclaimed; /* * Even if we did not try to evict anon pages at all, we want to @@ -1861,6 +1920,11 @@ static void shrink_zone(int priority, struct zone *zone, if (inactive_anon_is_low(zone, sc)) shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); + /* reclaim/compaction might need reclaim to continue */ + if (should_continue_reclaim(zone, nr_reclaimed, + sc->nr_scanned - nr_scanned, sc)) + goto restart; + throttle_vm_writeout(sc->gfp_mask); } @@ -2307,6 +2371,14 @@ loop_again: total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2) sc.may_writepage = 1; + /* + * Compact the zone for higher orders to reduce + * latencies for higher-order allocations that + * would ordinarily call try_to_compact_pages() + */ + if (sc.order > PAGE_ALLOC_COSTLY_ORDER) + compact_zone_order(zone, sc.order, sc.gfp_mask); + if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), end_zone, 0)) { all_zones_ok = 0; |
