diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 44 |
1 files changed, 42 insertions, 2 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 61d3a9a0d96f..e176bd3936da 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1904,6 +1904,24 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont, } #endif +/* is kswapd sleeping prematurely? */ +static int sleeping_prematurely(int order, long remaining) +{ + struct zone *zone; + + /* If a direct reclaimer woke kswapd within HZ/10, it's premature */ + if (remaining) + return 1; + + /* If after HZ/10, a zone is below the high mark, it's premature */ + for_each_populated_zone(zone) + if (!zone_watermark_ok(zone, order, high_wmark_pages(zone), + 0, 0)) + return 1; + + return 0; +} + /* * For kswapd, balance_pgdat() will work across all this node's zones until * they are all at high_wmark_pages(zone). @@ -2185,8 +2203,30 @@ static int kswapd(void *p) */ order = new_order; } else { - if (!freezing(current) && !kthread_should_stop()) - schedule(); + if (!freezing(current) && !kthread_should_stop()) { + long remaining = 0; + + /* Try to sleep for a short interval */ + if (!sleeping_prematurely(order, remaining)) { + remaining = schedule_timeout(HZ/10); + finish_wait(&pgdat->kswapd_wait, &wait); + prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE); + } + + /* + * 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(order, remaining)) + schedule(); + else { + if (remaining) + count_vm_event(KSWAPD_PREMATURE_FAST); + else + count_vm_event(KSWAPD_PREMATURE_SLOW); + } + } order = pgdat->kswapd_max_order; } |