diff options
| -rw-r--r-- | include/linux/compaction.h | 4 | ||||
| -rw-r--r-- | mm/compaction.c | 100 | ||||
| -rw-r--r-- | mm/internal.h | 1 | ||||
| -rw-r--r-- | mm/page_alloc.c | 17 |
4 files changed, 93 insertions, 29 deletions
diff --git a/include/linux/compaction.h b/include/linux/compaction.h index 133ddcf83397..ef658147e4e8 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -22,7 +22,7 @@ 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, - bool sync); + bool sync, bool *contended); extern int compact_pgdat(pg_data_t *pgdat, int order); extern unsigned long compaction_suitable(struct zone *zone, int order); @@ -64,7 +64,7 @@ static inline bool compaction_deferred(struct zone *zone, int order) #else static inline unsigned long try_to_compact_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *nodemask, - bool sync) + bool sync, bool *contended) { return COMPACT_CONTINUE; } diff --git a/mm/compaction.c b/mm/compaction.c index bcce7897e17a..7fcd3a52e68d 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -51,6 +51,47 @@ static inline bool migrate_async_suitable(int migratetype) } /* + * Compaction requires the taking of some coarse locks that are potentially + * very heavily contended. Check if the process needs to be scheduled or + * if the lock is contended. For async compaction, back out in the event + * if contention is severe. For sync compaction, schedule. + * + * Returns true if the lock is held. + * Returns false if the lock is released and compaction should abort + */ +static bool compact_checklock_irqsave(spinlock_t *lock, unsigned long *flags, + bool locked, struct compact_control *cc) +{ + if (need_resched() || spin_is_contended(lock)) { + if (locked) { + spin_unlock_irqrestore(lock, *flags); + locked = false; + } + + /* async aborts if taking too long or contended */ + if (!cc->sync) { + if (cc->contended) + *cc->contended = true; + return false; + } + + cond_resched(); + if (fatal_signal_pending(current)) + return false; + } + + if (!locked) + spin_lock_irqsave(lock, *flags); + return true; +} + +static inline bool compact_trylock_irqsave(spinlock_t *lock, + unsigned long *flags, struct compact_control *cc) +{ + return compact_checklock_irqsave(lock, flags, false, cc); +} + +/* * Isolate free pages onto a private freelist. Caller must hold zone->lock. * If @strict is true, will abort returning 0 on any invalid PFNs or non-free * pages inside of the pageblock (even though it may still end up isolating @@ -173,7 +214,7 @@ isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn) } /* Update the number of anon and file isolated pages in the zone */ -static void acct_isolated(struct zone *zone, struct compact_control *cc) +static void acct_isolated(struct zone *zone, bool locked, struct compact_control *cc) { struct page *page; unsigned int count[2] = { 0, }; @@ -181,8 +222,14 @@ static void acct_isolated(struct zone *zone, struct compact_control *cc) list_for_each_entry(page, &cc->migratepages, lru) count[!!page_is_file_cache(page)]++; - __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); - __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); + /* If locked we can use the interrupt unsafe versions */ + if (locked) { + __mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); + __mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); + } else { + mod_zone_page_state(zone, NR_ISOLATED_ANON, count[0]); + mod_zone_page_state(zone, NR_ISOLATED_FILE, count[1]); + } } /* Similar to reclaim, but different enough that they don't share logic */ @@ -228,6 +275,8 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc, struct list_head *migratelist = &cc->migratepages; isolate_mode_t mode = 0; struct lruvec *lruvec; + unsigned long flags; + bool locked; /* * Ensure that there are not too many pages isolated from the LRU @@ -247,25 +296,22 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc, /* Time to isolate some pages for migration */ cond_resched(); - spin_lock_irq(&zone->lru_lock); + spin_lock_irqsave(&zone->lru_lock, flags); + locked = true; for (; low_pfn < end_pfn; low_pfn++) { struct page *page; - bool locked = true; /* give a chance to irqs before checking need_resched() */ if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) { - spin_unlock_irq(&zone->lru_lock); + spin_unlock_irqrestore(&zone->lru_lock, flags); locked = false; } - if (need_resched() || spin_is_contended(&zone->lru_lock)) { - if (locked) - spin_unlock_irq(&zone->lru_lock); - cond_resched(); - spin_lock_irq(&zone->lru_lock); - if (fatal_signal_pending(current)) - break; - } else if (!locked) - spin_lock_irq(&zone->lru_lock); + + /* Check if it is ok to still hold the lock */ + locked = compact_checklock_irqsave(&zone->lru_lock, &flags, + locked, cc); + if (!locked) + break; /* * migrate_pfn does not necessarily start aligned to a @@ -349,9 +395,10 @@ isolate_migratepages_range(struct zone *zone, struct compact_control *cc, } } - acct_isolated(zone, cc); + acct_isolated(zone, locked, cc); - spin_unlock_irq(&zone->lru_lock); + if (locked) + spin_unlock_irqrestore(&zone->lru_lock, flags); trace_mm_compaction_isolate_migratepages(nr_scanned, nr_isolated); @@ -461,7 +508,16 @@ static void isolate_freepages(struct zone *zone, * are disabled */ isolated = 0; - spin_lock_irqsave(&zone->lock, flags); + + /* + * The zone lock must be held to isolate freepages. This + * unfortunately this is a very coarse lock and can be + * heavily contended if there are parallel allocations + * or parallel compactions. For async compaction do not + * spin on the lock + */ + if (!compact_trylock_irqsave(&zone->lock, &flags, cc)) + break; if (suitable_migration_target(page)) { end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn); isolated = isolate_freepages_block(pfn, end_pfn, @@ -773,7 +829,7 @@ out: static unsigned long compact_zone_order(struct zone *zone, int order, gfp_t gfp_mask, - bool sync) + bool sync, bool *contended) { struct compact_control cc = { .nr_freepages = 0, @@ -782,6 +838,7 @@ static unsigned long compact_zone_order(struct zone *zone, .migratetype = allocflags_to_migratetype(gfp_mask), .zone = zone, .sync = sync, + .contended = contended, }; INIT_LIST_HEAD(&cc.freepages); INIT_LIST_HEAD(&cc.migratepages); @@ -803,7 +860,7 @@ int sysctl_extfrag_threshold = 500; */ unsigned long try_to_compact_pages(struct zonelist *zonelist, int order, gfp_t gfp_mask, nodemask_t *nodemask, - bool sync) + bool sync, bool *contended) { enum zone_type high_zoneidx = gfp_zone(gfp_mask); int may_enter_fs = gfp_mask & __GFP_FS; @@ -827,7 +884,8 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist, nodemask) { int status; - status = compact_zone_order(zone, order, gfp_mask, sync); + status = compact_zone_order(zone, order, gfp_mask, sync, + contended); rc = max(status, rc); /* If a normal allocation would succeed, stop compacting */ diff --git a/mm/internal.h b/mm/internal.h index 3314f79d775a..b8c91b342e24 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -130,6 +130,7 @@ struct compact_control { int order; /* order a direct compactor needs */ int migratetype; /* MOVABLE, RECLAIMABLE etc */ struct zone *zone; + bool *contended; /* True if a lock was contended */ }; unsigned long diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 07f19248acb5..c66fb875104a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2102,7 +2102,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist, enum zone_type high_zoneidx, nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone, int migratetype, bool sync_migration, - bool *deferred_compaction, + bool *contended_compaction, bool *deferred_compaction, unsigned long *did_some_progress) { struct page *page; @@ -2117,7 +2117,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, current->flags |= PF_MEMALLOC; *did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask, - nodemask, sync_migration); + nodemask, sync_migration, + contended_compaction); current->flags &= ~PF_MEMALLOC; if (*did_some_progress != COMPACT_SKIPPED) { @@ -2163,7 +2164,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order, struct zonelist *zonelist, enum zone_type high_zoneidx, nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone, int migratetype, bool sync_migration, - bool *deferred_compaction, + bool *contended_compaction, bool *deferred_compaction, unsigned long *did_some_progress) { return NULL; @@ -2336,6 +2337,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, unsigned long did_some_progress; bool sync_migration = false; bool deferred_compaction = false; + bool contended_compaction = false; /* * In the slowpath, we sanity check order to avoid ever trying to @@ -2425,6 +2427,7 @@ rebalance: nodemask, alloc_flags, preferred_zone, migratetype, sync_migration, + &contended_compaction, &deferred_compaction, &did_some_progress); if (page) @@ -2434,10 +2437,11 @@ rebalance: /* * If compaction is deferred for high-order allocations, it is because * sync compaction recently failed. In this is the case and the caller - * has requested the system not be heavily disrupted, fail the - * allocation now instead of entering direct reclaim + * requested a movable allocation that does not heavily disrupt the + * system then fail the allocation instead of entering direct reclaim. */ - if (deferred_compaction && (gfp_mask & __GFP_NO_KSWAPD)) + if ((deferred_compaction || contended_compaction) && + (gfp_mask & __GFP_NO_KSWAPD)) goto nopage; /* Try direct reclaim and then allocating */ @@ -2508,6 +2512,7 @@ rebalance: nodemask, alloc_flags, preferred_zone, migratetype, sync_migration, + &contended_compaction, &deferred_compaction, &did_some_progress); if (page) |