diff options
| -rw-r--r-- | mm/memory_hotplug.c | 6 | ||||
| -rw-r--r-- | mm/vmscan.c | 120 |
2 files changed, 71 insertions, 55 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 6fa7208bcd56..b63d7d1239df 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1208,7 +1208,11 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) arch_refresh_nodedata(nid, pgdat); } else { - /* Reset the nr_zones, order and classzone_idx before reuse */ + /* + * Reset the nr_zones, order and classzone_idx before reuse. + * Note that kswapd will init kswapd_classzone_idx properly + * when it starts in the near future. + */ pgdat->nr_zones = 0; pgdat->kswapd_order = 0; pgdat->kswapd_classzone_idx = 0; diff --git a/mm/vmscan.c b/mm/vmscan.c index 8c553fa0d800..8ce39867140b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3049,14 +3049,36 @@ static void age_active_anon(struct pglist_data *pgdat, } while (memcg); } -static bool zone_balanced(struct zone *zone, int order, int classzone_idx) +/* + * Returns true if there is an eligible zone balanced for the request order + * and classzone_idx + */ +static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx) { - unsigned long mark = high_wmark_pages(zone); + int i; + unsigned long mark = -1; + struct zone *zone; - if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx)) - return false; + for (i = 0; i <= classzone_idx; i++) { + zone = pgdat->node_zones + i; - return true; + if (!managed_zone(zone)) + continue; + + mark = high_wmark_pages(zone); + if (zone_watermark_ok_safe(zone, order, mark, classzone_idx)) + return true; + } + + /* + * If a node has no populated zone within classzone_idx, it does not + * need balancing by definition. This can happen if a zone-restricted + * allocation tries to wake a remote kswapd. + */ + if (mark == -1) + return true; + + return false; } /* Clear pgdat state for congested, dirty or under writeback. */ @@ -3075,8 +3097,6 @@ static void clear_pgdat_congested(pg_data_t *pgdat) */ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) { - int i; - /* * The throttled processes are normally woken up in balance_pgdat() as * soon as allow_direct_reclaim() is true. But there is a potential @@ -3097,16 +3117,9 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx) if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) return true; - for (i = 0; i <= classzone_idx; i++) { - struct zone *zone = pgdat->node_zones + i; - - if (!managed_zone(zone)) - continue; - - if (zone_balanced(zone, order, classzone_idx)) { - clear_pgdat_congested(pgdat); - return true; - } + if (pgdat_balanced(pgdat, order, classzone_idx)) { + clear_pgdat_congested(pgdat); + return true; } return false; @@ -3212,23 +3225,12 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx) } /* - * Only reclaim if there are no eligible zones. Check from - * high to low zone as allocations prefer higher zones. - * Scanning from low to high zone would allow congestion to be - * cleared during a very small window when a small low - * zone was balanced even under extreme pressure when the - * overall node may be congested. Note that sc.reclaim_idx - * is not used as buffer_heads_over_limit may have adjusted - * it. + * Only reclaim if there are no eligible zones. Note that + * sc.reclaim_idx is not used as buffer_heads_over_limit may + * have adjusted it. */ - for (i = classzone_idx; i >= 0; i--) { - zone = pgdat->node_zones + i; - if (!managed_zone(zone)) - continue; - - if (zone_balanced(zone, sc.order, classzone_idx)) - goto out; - } + if (pgdat_balanced(pgdat, sc.order, classzone_idx)) + goto out; /* * Do some background aging of the anon list, to give @@ -3295,6 +3297,22 @@ out: return sc.order; } +/* + * pgdat->kswapd_classzone_idx is the highest zone index that a recent + * allocation request woke kswapd for. When kswapd has not woken recently, + * the value is MAX_NR_ZONES which is not a valid index. This compares a + * given classzone and returns it or the highest classzone index kswapd + * was recently woke for. + */ +static enum zone_type kswapd_classzone_idx(pg_data_t *pgdat, + enum zone_type classzone_idx) +{ + if (pgdat->kswapd_classzone_idx == MAX_NR_ZONES) + return classzone_idx; + + return max(pgdat->kswapd_classzone_idx, classzone_idx); +} + static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order, unsigned int classzone_idx) { @@ -3336,7 +3354,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_o * the previous request that slept prematurely. */ if (remaining) { - pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx); + pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); pgdat->kswapd_order = max(pgdat->kswapd_order, reclaim_order); } @@ -3390,7 +3408,8 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_o */ static int kswapd(void *p) { - unsigned int alloc_order, reclaim_order, classzone_idx; + unsigned int alloc_order, reclaim_order; + unsigned int classzone_idx = MAX_NR_ZONES - 1; pg_data_t *pgdat = (pg_data_t*)p; struct task_struct *tsk = current; @@ -3420,20 +3439,23 @@ static int kswapd(void *p) tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; set_freezable(); - pgdat->kswapd_order = alloc_order = reclaim_order = 0; - pgdat->kswapd_classzone_idx = classzone_idx = 0; + pgdat->kswapd_order = 0; + pgdat->kswapd_classzone_idx = MAX_NR_ZONES; for ( ; ; ) { bool ret; + alloc_order = reclaim_order = pgdat->kswapd_order; + classzone_idx = kswapd_classzone_idx(pgdat, classzone_idx); + kswapd_try_sleep: kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order, classzone_idx); /* Read the new order and classzone_idx */ alloc_order = reclaim_order = pgdat->kswapd_order; - classzone_idx = pgdat->kswapd_classzone_idx; + classzone_idx = kswapd_classzone_idx(pgdat, 0); pgdat->kswapd_order = 0; - pgdat->kswapd_classzone_idx = 0; + pgdat->kswapd_classzone_idx = MAX_NR_ZONES; ret = try_to_freeze(); if (kthread_should_stop()) @@ -3459,9 +3481,6 @@ kswapd_try_sleep: reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx); if (reclaim_order < alloc_order) goto kswapd_try_sleep; - - alloc_order = reclaim_order = pgdat->kswapd_order; - classzone_idx = pgdat->kswapd_classzone_idx; } tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); @@ -3477,7 +3496,6 @@ kswapd_try_sleep: void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) { pg_data_t *pgdat; - int z; if (!managed_zone(zone)) return; @@ -3485,7 +3503,8 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) return; pgdat = zone->zone_pgdat; - pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx); + pgdat->kswapd_classzone_idx = kswapd_classzone_idx(pgdat, + classzone_idx); pgdat->kswapd_order = max(pgdat->kswapd_order, order); if (!waitqueue_active(&pgdat->kswapd_wait)) return; @@ -3494,17 +3513,10 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) if (pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES) return; - /* Only wake kswapd if all zones are unbalanced */ - for (z = 0; z <= classzone_idx; z++) { - zone = pgdat->node_zones + z; - if (!managed_zone(zone)) - continue; - - if (zone_balanced(zone, order, classzone_idx)) - return; - } + if (pgdat_balanced(pgdat, order, classzone_idx)) + return; - trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order); + trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, classzone_idx, order); wake_up_interruptible(&pgdat->kswapd_wait); } |