diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 133 |
1 files changed, 65 insertions, 68 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 7f30961..196709f5 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1177,7 +1177,11 @@ int isolate_lru_page(struct page *page) } /* - * Are there way too many processes in the direct reclaim path already? + * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and + * then get resheduled. When there are massive number of tasks doing page + * allocation, such sleeping direct reclaimers may keep piling up on each CPU, + * the LRU list will go small and be scanned faster than necessary, leading to + * unnecessary swapping, thrashing and OOM. */ static int too_many_isolated(struct zone *zone, int file, struct scan_control *sc) @@ -1198,6 +1202,14 @@ static int too_many_isolated(struct zone *zone, int file, isolated = zone_page_state(zone, NR_ISOLATED_ANON); } + /* + * GFP_NOIO/GFP_NOFS callers are allowed to isolate more pages, so they + * won't get blocked by normal direct-reclaimers, forming a circular + * deadlock. + */ + if ((sc->gfp_mask & GFP_IOFS) == GFP_IOFS) + inactive >>= 3; + return isolated > inactive; } @@ -2440,12 +2452,16 @@ static bool zone_balanced(struct zone *zone, int order, } /* - * pgdat_balanced is used when checking if a node is balanced for high-order - * allocations. Only zones that meet watermarks and are in a zone allowed - * by the callers classzone_idx are added to balanced_pages. The total of - * balanced pages must be at least 25% of the zones allowed by classzone_idx - * for the node to be considered balanced. Forcing all zones to be balanced - * for high orders can cause excessive reclaim when there are imbalanced zones. + * pgdat_balanced() is used when checking if a node is balanced. + * + * For order-0, all zones must be balanced! + * + * For high-order allocations only zones that meet watermarks and are in a + * zone allowed by the callers classzone_idx are added to balanced_pages. The + * total of balanced pages must be at least 25% of the zones allowed by + * classzone_idx for the node to be considered balanced. Forcing all zones to + * be balanced for high orders can cause excessive reclaim when there are + * imbalanced zones. * The choice of 25% is due to * o a 16M DMA zone that is balanced will not balance a zone on any * reasonable sized machine @@ -2455,17 +2471,43 @@ static bool zone_balanced(struct zone *zone, int order, * Similarly, on x86-64 the Normal zone would need to be at least 1G * to balance a node on its own. These seemed like reasonable ratios. */ -static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, - int classzone_idx) +static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) { unsigned long present_pages = 0; + unsigned long balanced_pages = 0; int i; - for (i = 0; i <= classzone_idx; i++) - present_pages += pgdat->node_zones[i].present_pages; + /* Check the watermark levels */ + for (i = 0; i <= classzone_idx; i++) { + struct zone *zone = pgdat->node_zones + i; + + if (!populated_zone(zone)) + continue; - /* A special case here: if zone has no page, we think it's balanced */ - return balanced_pages >= (present_pages >> 2); + present_pages += zone->present_pages; + + /* + * A special case here: + * + * balance_pgdat() skips over all_unreclaimable after + * DEF_PRIORITY. Effectively, it considers them balanced so + * they must be considered balanced here as well! + */ + if (zone->all_unreclaimable) { + balanced_pages += zone->present_pages; + continue; + } + + if (zone_balanced(zone, order, 0, i)) + balanced_pages += zone->present_pages; + else if (!order) + return false; + } + + if (order) + return balanced_pages >= (present_pages >> 2); + else + return true; } /* @@ -2477,10 +2519,6 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, int classzone_idx) { - int i; - unsigned long balanced = 0; - bool all_zones_ok = true; - /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ if (remaining) return false; @@ -2499,39 +2537,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, return false; } - /* Check the watermark levels */ - for (i = 0; i <= classzone_idx; i++) { - struct zone *zone = pgdat->node_zones + i; - - if (!populated_zone(zone)) - continue; - - /* - * balance_pgdat() skips over all_unreclaimable after - * DEF_PRIORITY. Effectively, it considers them balanced so - * they must be considered balanced here as well if kswapd - * is to sleep - */ - if (zone->all_unreclaimable) { - balanced += zone->present_pages; - continue; - } - - if (!zone_balanced(zone, order, 0, i)) - all_zones_ok = false; - else - balanced += zone->present_pages; - } - - /* - * For high-order requests, the balanced zones must contain at least - * 25% of the nodes pages for kswapd to sleep. For order-0, all zones - * must be balanced - */ - if (order) - return pgdat_balanced(pgdat, balanced, classzone_idx); - else - return all_zones_ok; + return pgdat_balanced(pgdat, order, classzone_idx); } /* @@ -2558,8 +2564,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, static unsigned long balance_pgdat(pg_data_t *pgdat, int order, int *classzone_idx) { - int all_zones_ok; - unsigned long balanced; + struct zone *unbalanced_zone; int i; int end_zone = 0; /* Inclusive. 0 = ZONE_DMA */ unsigned long total_scanned; @@ -2592,8 +2597,7 @@ loop_again: unsigned long lru_pages = 0; int has_under_min_watermark_zone = 0; - all_zones_ok = 1; - balanced = 0; + unbalanced_zone = NULL; /* * Scan in the highmem->dma direction for the highest @@ -2731,7 +2735,7 @@ loop_again: } if (!zone_balanced(zone, testorder, 0, end_zone)) { - all_zones_ok = 0; + unbalanced_zone = zone; /* * We are still under min water mark. This * means that we have a GFP_ATOMIC allocation @@ -2749,8 +2753,6 @@ loop_again: * speculatively avoid congestion waits */ zone_clear_flag(zone, ZONE_CONGESTED); - if (i <= *classzone_idx) - balanced += zone->present_pages; } } @@ -2764,7 +2766,7 @@ loop_again: pfmemalloc_watermark_ok(pgdat)) wake_up(&pgdat->pfmemalloc_wait); - if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx))) + if (pgdat_balanced(pgdat, order, *classzone_idx)) break; /* kswapd: all done */ /* * OK, kswapd is getting into trouble. Take a nap, then take @@ -2773,8 +2775,8 @@ loop_again: if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) { if (has_under_min_watermark_zone) count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT); - else - congestion_wait(BLK_RW_ASYNC, HZ/10); + else if (unbalanced_zone) + wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10); } /* @@ -2788,12 +2790,7 @@ loop_again: } while (--sc.priority >= 0); out: - /* - * order-0: All zones must meet high watermark for a balanced node - * high-order: Balanced zones must make up at least 25% of the node - * for the node to be balanced - */ - if (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) { + if (!pgdat_balanced(pgdat, order, *classzone_idx)) { cond_resched(); try_to_freeze(); @@ -3125,8 +3122,8 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim) not required for correctness. So if the last cpu in a node goes away, we get changed to run anywhere: as the first one comes back, restore their cpu bindings. */ -static int __devinit cpu_callback(struct notifier_block *nfb, - unsigned long action, void *hcpu) +static int cpu_callback(struct notifier_block *nfb, unsigned long action, + void *hcpu) { int nid; |
