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authorMel Gorman <mgorman@suse.de>2012-08-01 03:44:39 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-08-01 05:42:46 +0400
commit68243e76ee343d63c6cf76978588a885951e2818 (patch)
treee6ec975265272c81e03312e1ebc1c27fd6fdfa19
parent5515061d22f0f9976ae7815864bfd22042d36848 (diff)
downloadlinux-68243e76ee343d63c6cf76978588a885951e2818.tar.xz
mm: account for the number of times direct reclaimers get throttled
Under significant pressure when writing back to network-backed storage, direct reclaimers may get throttled. This is expected to be a short-lived event and the processes get woken up again but processes do get stalled. This patch counts how many times such stalling occurs. It's up to the administrator whether to reduce these stalls by increasing min_free_kbytes. Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: David Miller <davem@davemloft.net> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/vm_event_item.h1
-rw-r--r--mm/vmscan.c3
-rw-r--r--mm/vmstat.c1
3 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 06f8e3858251..57f7b1091511 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -30,6 +30,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
FOR_ALL_ZONES(PGSTEAL_DIRECT),
FOR_ALL_ZONES(PGSCAN_KSWAPD),
FOR_ALL_ZONES(PGSCAN_DIRECT),
+ PGSCAN_DIRECT_THROTTLE,
#ifdef CONFIG_NUMA
PGSCAN_ZONE_RECLAIM_FAILED,
#endif
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 021a44a7bd20..88804017e7d6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2167,6 +2167,9 @@ static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
if (pfmemalloc_watermark_ok(pgdat))
return;
+ /* Account for the throttling */
+ count_vm_event(PGSCAN_DIRECT_THROTTLE);
+
/*
* If the caller cannot enter the filesystem, it's possible that it
* is due to the caller holding an FS lock or performing a journal
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 1bbbbd9776ad..df7a6748231d 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -745,6 +745,7 @@ const char * const vmstat_text[] = {
TEXTS_FOR_ZONES("pgsteal_direct")
TEXTS_FOR_ZONES("pgscan_kswapd")
TEXTS_FOR_ZONES("pgscan_direct")
+ "pgscan_direct_throttle",
#ifdef CONFIG_NUMA
"zone_reclaim_failed",