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| author | Ingo Molnar <mingo@elte.hu> | 2010-10-07 09:43:11 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-10-07 09:43:11 +0200 |
| commit | d4f8f217b8a5d5bd02af979650418dca4caec472 (patch) | |
| tree | af047bfa9729c975e24cb7624107574e884d3a57 /mm/mmzone.c | |
| parent | 2dfbf4dfbe47a484bae20456c12b40763b9b6af7 (diff) | |
| parent | 773e3f93577ffb493fb7c39b1a6ecf39b5748e87 (diff) | |
Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu
Diffstat (limited to 'mm/mmzone.c')
| -rw-r--r-- | mm/mmzone.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/mm/mmzone.c b/mm/mmzone.c index f5b7d176021..e35bfb82c85 100644 --- a/mm/mmzone.c +++ b/mm/mmzone.c @@ -87,3 +87,24 @@ int memmap_valid_within(unsigned long pfn, return 1; } #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */ + +#ifdef CONFIG_SMP +/* Called when a more accurate view of NR_FREE_PAGES is needed */ +unsigned long zone_nr_free_pages(struct zone *zone) +{ + unsigned long nr_free_pages = zone_page_state(zone, NR_FREE_PAGES); + + /* + * While kswapd is awake, it is considered the zone is under some + * memory pressure. Under pressure, there is a risk that + * per-cpu-counter-drift will allow the min watermark to be breached + * potentially causing a live-lock. While kswapd is awake and + * free pages are low, get a better estimate for free pages + */ + if (nr_free_pages < zone->percpu_drift_mark && + !waitqueue_active(&zone->zone_pgdat->kswapd_wait)) + return zone_page_state_snapshot(zone, NR_FREE_PAGES); + + return nr_free_pages; +} +#endif /* CONFIG_SMP */ |