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| author | Mel Gorman <mel@csn.ul.ie> | 2009-06-16 15:33:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-16 19:47:46 -0700 |
| commit | 24cf72518c79cdcda486ed26074ff8151291cf65 (patch) | |
| tree | 0db04965fb57135e68edf62c332c3a3825c1e3b5 /include/linux/vmstat.h | |
| parent | fa5e084e43eb14c14942027e1e2e894aeed96097 (diff) | |
| download | linux-24cf72518c79cdcda486ed26074ff8151291cf65.tar.gz linux-24cf72518c79cdcda486ed26074ff8151291cf65.tar.bz2 linux-24cf72518c79cdcda486ed26074ff8151291cf65.zip | |
vmscan: count the number of times zone_reclaim() scans and fails
On NUMA machines, the administrator can configure zone_reclaim_mode that
is a more targetted form of direct reclaim. On machines with large NUMA
distances for example, a zone_reclaim_mode defaults to 1 meaning that
clean unmapped pages will be reclaimed if the zone watermarks are not
being met.
There is a heuristic that determines if the scan is worthwhile but it is
possible that the heuristic will fail and the CPU gets tied up scanning
uselessly. Detecting the situation requires some guesswork and
experimentation so this patch adds a counter "zreclaim_failed" to
/proc/vmstat. If during high CPU utilisation this counter is increasing
rapidly, then the resolution to the problem may be to set
/proc/sys/vm/zone_reclaim_mode to 0.
[akpm@linux-foundation.org: name things consistently]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/vmstat.h')
| -rw-r--r-- | include/linux/vmstat.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h index ff4696c6dce3..81a97cf8f0a0 100644 --- a/include/linux/vmstat.h +++ b/include/linux/vmstat.h @@ -36,6 +36,9 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, FOR_ALL_ZONES(PGSTEAL), FOR_ALL_ZONES(PGSCAN_KSWAPD), FOR_ALL_ZONES(PGSCAN_DIRECT), +#ifdef CONFIG_NUMA + PGSCAN_ZONE_RECLAIM_FAILED, +#endif PGINODESTEAL, SLABS_SCANNED, KSWAPD_STEAL, KSWAPD_INODESTEAL, PAGEOUTRUN, ALLOCSTALL, PGROTATED, #ifdef CONFIG_HUGETLB_PAGE |