From dc83edd941f412e938841b4989be24aa288a1aa6 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 13 Jan 2011 15:46:26 -0800 Subject: [PATCH] mm: kswapd: use the classzone idx that kswapd was using for sleeping_prematurely() When kswapd is woken up for a high-order allocation, it takes account of the highest usable zone by the caller (the classzone idx). During allocation, this index is used to select the lowmem_reserve[] that should be applied to the watermark calculation in zone_watermark_ok(). When balancing a node, kswapd considers the highest unbalanced zone to be the classzone index. This will always be at least be the callers classzone_idx and can be higher. However, sleeping_prematurely() always considers the lowest zone (e.g. ZONE_DMA) to be the classzone index. This means that sleeping_prematurely() can consider a zone to be balanced that is unusable by the allocation request that originally woke kswapd. This patch changes sleeping_prematurely() to use a classzone_idx matching the value it used in balance_pgdat(). Signed-off-by: Mel Gorman Reviewed-by: Minchan Kim Reviewed-by: Eric B Munson Cc: KAMEZAWA Hiroyuki Cc: Simon Kirby Cc: KOSAKI Motohiro Cc: Shaohua Li Cc: Dave Hansen Cc: Johannes Weiner Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 388a0447b8e8..cfdef0bcc7ab 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2227,7 +2227,8 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages, } /* is kswapd sleeping prematurely? */ -static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) +static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining, + int classzone_idx) { int i; unsigned long balanced = 0; @@ -2235,7 +2236,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ if (remaining) - return 1; + return true; /* Check the watermark levels */ for (i = 0; i < pgdat->nr_zones; i++) { @@ -2256,7 +2257,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) } if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), - 0, 0)) + classzone_idx, 0)) all_zones_ok = false; else balanced += zone->present_pages; @@ -2268,7 +2269,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) * must be balanced */ if (order) - return pgdat_balanced(pgdat, balanced, 0); + return pgdat_balanced(pgdat, balanced, classzone_idx); else return !all_zones_ok; } @@ -2295,7 +2296,7 @@ static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) * of pages is balanced across the zones. */ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, - int classzone_idx) + int *classzone_idx) { int all_zones_ok; unsigned long balanced; @@ -2358,6 +2359,7 @@ loop_again: if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone), 0, 0)) { end_zone = i; + *classzone_idx = i; break; } } @@ -2451,12 +2453,12 @@ loop_again: * spectulatively avoid congestion waits */ zone_clear_flag(zone, ZONE_CONGESTED); - if (i <= classzone_idx) + if (i <= *classzone_idx) balanced += zone->present_pages; } } - if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, classzone_idx))) + if (all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx))) break; /* kswapd: all done */ /* * OK, kswapd is getting into trouble. Take a nap, then take @@ -2485,7 +2487,7 @@ out: * 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 (!(all_zones_ok || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))) { cond_resched(); try_to_freeze(); @@ -2546,10 +2548,11 @@ out: * if another caller entered the allocator slow path while kswapd * was awake, order will remain at the higher level */ + *classzone_idx = end_zone; return order; } -static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) +static void kswapd_try_to_sleep(pg_data_t *pgdat, int order, int classzone_idx) { long remaining = 0; DEFINE_WAIT(wait); @@ -2560,7 +2563,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); /* Try to sleep for a short interval */ - if (!sleeping_prematurely(pgdat, order, remaining)) { + if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { remaining = schedule_timeout(HZ/10); finish_wait(&pgdat->kswapd_wait, &wait); prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); @@ -2570,7 +2573,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order) * After a short sleep, check if it was a premature sleep. If not, then * go fully to sleep until explicitly woken up. */ - if (!sleeping_prematurely(pgdat, order, remaining)) { + if (!sleeping_prematurely(pgdat, order, remaining, classzone_idx)) { trace_mm_vmscan_kswapd_sleep(pgdat->node_id); /* @@ -2658,7 +2661,7 @@ static int kswapd(void *p) order = new_order; classzone_idx = new_classzone_idx; } else { - kswapd_try_to_sleep(pgdat, order); + kswapd_try_to_sleep(pgdat, order, classzone_idx); order = pgdat->kswapd_max_order; classzone_idx = pgdat->classzone_idx; pgdat->kswapd_max_order = 0; @@ -2675,7 +2678,7 @@ static int kswapd(void *p) */ if (!ret) { trace_mm_vmscan_kswapd_wake(pgdat->node_id, order); - order = balance_pgdat(pgdat, order, classzone_idx); + order = balance_pgdat(pgdat, order, &classzone_idx); } } return 0; -- 2.30.2