diff options
Diffstat (limited to 'mm/compaction.c')
| -rw-r--r-- | mm/compaction.c | 53 |
1 files changed, 31 insertions, 22 deletions
diff --git a/mm/compaction.c b/mm/compaction.c index 74770e40cfe5..5039c964f5c8 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -367,22 +367,30 @@ static unsigned long isolate_freepages_block(struct compact_control *cc, goto isolate_fail; /* - * 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. + * If we already hold the lock, we can skip some rechecking. + * Note that if we hold the lock now, checked_pageblock was + * already set in some previous iteration (or strict is true), + * so it is correct to skip the suitable migration target + * recheck as well. */ - if (!locked) + 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, &flags, cc); - if (!locked) - break; + if (!locked) + break; - /* Recheck this is a buddy page under lock */ - if (!PageBuddy(page)) - goto isolate_fail; + /* Recheck this is a buddy page under lock */ + if (!PageBuddy(page)) + goto isolate_fail; + } /* Found a free page, break it into order-0 pages */ isolated = split_free_page(page); @@ -644,19 +652,20 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, page_count(page) > page_mapcount(page)) continue; - /* If the lock is not held, try to take it */ - if (!locked) + /* If we already hold the lock, we can skip some rechecking */ + if (!locked) { locked = compact_trylock_irqsave(&zone->lru_lock, &flags, cc); - if (!locked) - break; + if (!locked) + break; - /* Recheck PageLRU and PageTransHuge under lock */ - if (!PageLRU(page)) - continue; - if (PageTransHuge(page)) { - low_pfn += (1 << compound_order(page)) - 1; - continue; + /* Recheck PageLRU and PageTransHuge under lock */ + if (!PageLRU(page)) + continue; + if (PageTransHuge(page)) { + low_pfn += (1 << compound_order(page)) - 1; + continue; + } } lruvec = mem_cgroup_page_lruvec(page, zone); |