--- linux/mm/vmscan.c.orig Wed May 31 20:13:37 2000 +++ linux/mm/vmscan.c Sat Jul 1 03:29:00 2000 @@ -419,6 +419,48 @@ } /* + * Check if there is any memory pressure (free_pages < pages_low) + */ +static inline int memory_pressure(void) +{ + pg_data_t *pgdat = pgdat_list; + + do { + int i; + for(i = 0; i < MAX_NR_ZONES; i++) { + zone_t *zone = pgdat->node_zones+ i; + if (!zone->size && + zone->free_pages < zone->pages_low) + return 1; + } + pgdat = pgdat->node_next; + } while (pgdat); + + return 0; +} + +/* + * Check if there is any memory pressure (free_pages < pages_low) + */ +static inline int keep_kswapd_awake(void) +{ + pg_data_t *pgdat = pgdat_list; + + do { + int i; + for(i = 0; i < MAX_NR_ZONES; i++) { + zone_t *zone = pgdat->node_zones+ i; + if (!zone->size && + zone->zone_wake_kswapd) + return 1; + } + pgdat = pgdat->node_next; + } while (pgdat); + + return 0; +} + +/* * We need to make the locks finer granularity, but right * now we need this so that we can do page allocations * without holding the kernel lock etc. @@ -442,7 +484,20 @@ priority = 64; do { + /* should __GFP_WAIT be checked? + * assume not - not WAITING for a free page + * let more important task execute before + * continuing (Note: kswapd does not use it). + */ + if (current->need_resched) { + schedule(); + /* time has passed - pressure too? */ + if (!memory_pressure()) + goto done; + } + while (shrink_mmap(priority, gfp_mask)) { + /* check __GFP_WAIT ? see below */ if (!--count) goto done; } @@ -477,16 +532,21 @@ if (--swap_count < 0) break; - } while (--priority >= 0); + priority--; + } while (priority >= 0); /* Always end on a shrink_mmap.. */ while (shrink_mmap(0, gfp_mask)) { + if (current->need_resched) + schedule(); + if (!memory_pressure()) + return 1; if (!--count) goto done; } /* We return 1 if we are freed some page */ return (count != FREE_COUNT); - + done: return 1; } @@ -530,29 +590,12 @@ tsk->flags |= PF_MEMALLOC; for (;;) { - pg_data_t *pgdat; - int something_to_do = 0; - - pgdat = pgdat_list; - do { - int i; - for(i = 0; i < MAX_NR_ZONES; i++) { - zone_t *zone = pgdat->node_zones+ i; - if (tsk->need_resched) - schedule(); - if (!zone->size || !zone->zone_wake_kswapd) - continue; - if (zone->free_pages < zone->pages_low) - something_to_do = 1; - do_try_to_free_pages(GFP_KSWAPD); - } - pgdat = pgdat->node_next; - } while (pgdat); - - if (!something_to_do) { - tsk->state = TASK_INTERRUPTIBLE; - interruptible_sleep_on(&kswapd_wait); + if (!keep_kswapd_awake()) { + tsk->state = TASK_INTERRUPTIBLE; + interruptible_sleep_on(&kswapd_wait); } + + do_try_to_free_pages(GFP_KSWAPD); } }