Commit 68243e76 authored Jul 31, 2012 by Mel Gorman Committed by Linus Torvalds Jul 31, 2012

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>

parent 5515061d

include/linux/vm_event_item.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

mm/vmscan.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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

mm/vmstat.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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",

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