diff options
Diffstat (limited to 'mm/compaction.c')
| -rw-r--r-- | mm/compaction.c | 90 |
1 files changed, 34 insertions, 56 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index 00a5126b6548..5325211398f8 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -382,24 +382,25 @@ static bool test_and_set_skip(struct compact_control *cc, struct page *page, /* * Compaction requires the taking of some coarse locks that are potentially - * very heavily contended. For async compaction, back out if the lock cannot - * be taken immediately. For sync compaction, spin on the lock if needed. + * very heavily contended. For async compaction, trylock and record if the + * lock is contended. The lock will still be acquired but compaction will + * abort when the current block is finished regardless of success rate. + * Sync compaction acquires the lock. * - * Returns true if the lock is held - * Returns false if the lock is not held and compaction should abort + * Always returns true which makes it easier to track lock state in callers. */ -static bool compact_trylock_irqsave(spinlock_t *lock, unsigned long *flags, +static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags, struct compact_control *cc) { - if (cc->mode == MIGRATE_ASYNC) { - if (!spin_trylock_irqsave(lock, *flags)) { - cc->contended = true; - return false; - } - } else { - spin_lock_irqsave(lock, *flags); + /* Track if the lock is contended in async mode */ + if (cc->mode == MIGRATE_ASYNC && !cc->contended) { + if (spin_trylock_irqsave(lock, *flags)) + return true; + + cc->contended = true; } + spin_lock_irqsave(lock, *flags); return true; } @@ -432,10 +433,8 @@ static bool compact_unlock_should_abort(spinlock_t *lock, } if (need_resched()) { - if (cc->mode == MIGRATE_ASYNC) { + if (cc->mode == MIGRATE_ASYNC) cc->contended = true; - return true; - } cond_resched(); } @@ -455,10 +454,8 @@ static inline bool compact_should_abort(struct compact_control *cc) { /* async compaction aborts if contended */ if (need_resched()) { - if (cc->mode == MIGRATE_ASYNC) { + if (cc->mode == MIGRATE_ASYNC) cc->contended = true; - return true; - } cond_resched(); } @@ -535,18 +532,8 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, * recheck as well. */ if (!locked) { - /* - * The zone lock must be held to isolate freepages. - * 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 and we acquire the lock as late as - * possible. - */ - locked = compact_trylock_irqsave(&cc->zone->lock, + locked = compact_lock_irqsave(&cc->zone->lock, &flags, cc); - if (!locked) - break; /* Recheck this is a buddy page under lock */ if (!PageBuddy(page)) @@ -900,15 +887,9 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, /* If we already hold the lock, we can skip some rechecking */ if (!locked) { - locked = compact_trylock_irqsave(zone_lru_lock(zone), + locked = compact_lock_irqsave(zone_lru_lock(zone), &flags, cc); - /* Allow future scanning if the lock is contended */ - if (!locked) { - clear_pageblock_skip(page); - break; - } - /* Try get exclusive access under lock */ if (!skip_updated) { skip_updated = true; @@ -951,9 +932,12 @@ isolate_success: /* * Avoid isolating too much unless this block is being - * rescanned (e.g. dirty/writeback pages, parallel allocation). + * rescanned (e.g. dirty/writeback pages, parallel allocation) + * or a lock is contended. For contention, isolate quickly to + * potentially remove one source of contention. */ - if (cc->nr_migratepages == COMPACT_CLUSTER_MAX && !cc->rescan) { + if (cc->nr_migratepages == COMPACT_CLUSTER_MAX && + !cc->rescan && !cc->contended) { ++low_pfn; break; } @@ -1416,12 +1400,8 @@ static void isolate_freepages(struct compact_control *cc) isolate_freepages_block(cc, &isolate_start_pfn, block_end_pfn, freelist, false); - /* - * If we isolated enough freepages, or aborted due to lock - * contention, terminate. - */ - if ((cc->nr_freepages >= cc->nr_migratepages) - || cc->contended) { + /* Are enough freepages isolated? */ + if (cc->nr_freepages >= cc->nr_migratepages) { if (isolate_start_pfn >= block_end_pfn) { /* * Restart at previous pageblock if more @@ -1463,13 +1443,8 @@ static struct page *compaction_alloc(struct page *migratepage, struct compact_control *cc = (struct compact_control *)data; struct page *freepage; - /* - * Isolate free pages if necessary, and if we are not aborting due to - * contention. - */ if (list_empty(&cc->freepages)) { - if (!cc->contended) - isolate_freepages(cc); + isolate_freepages(cc); if (list_empty(&cc->freepages)) return NULL; @@ -1733,7 +1708,7 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone, low_pfn = isolate_migratepages_block(cc, low_pfn, block_end_pfn, isolate_mode); - if (!low_pfn || cc->contended) + if (!low_pfn) return ISOLATE_ABORT; /* @@ -1763,9 +1738,7 @@ static enum compact_result __compact_finished(struct compact_control *cc) { unsigned int order; const int migratetype = cc->migratetype; - - if (cc->contended || fatal_signal_pending(current)) - return COMPACT_CONTENDED; + int ret; /* Compaction run completes if the migrate and free scanner meet */ if (compact_scanners_met(cc)) { @@ -1800,6 +1773,7 @@ static enum compact_result __compact_finished(struct compact_control *cc) return COMPACT_CONTINUE; /* Direct compactor: Is a suitable page free? */ + ret = COMPACT_NO_SUITABLE_PAGE; for (order = cc->order; order < MAX_ORDER; order++) { struct free_area *area = &cc->zone->free_area[order]; bool can_steal; @@ -1839,11 +1813,15 @@ static enum compact_result __compact_finished(struct compact_control *cc) return COMPACT_SUCCESS; } - return COMPACT_CONTINUE; + ret = COMPACT_CONTINUE; + break; } } - return COMPACT_NO_SUITABLE_PAGE; + if (cc->contended || fatal_signal_pending(current)) + ret = COMPACT_CONTENDED; + + return ret; } static enum compact_result compact_finished(struct compact_control *cc) |