On Tue, Apr 26, 2011 at 10:35:10PM +1000, NeilBrown wrote: > On Tue, 26 Apr 2011 08:36:54 +0100 Mel Gorman <mgorman@xxxxxxx> wrote: > > > 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@xxxxxxx> > > --- > > include/linux/vm_event_item.h | 1 + > > mm/vmscan.c | 1 + > > mm/vmstat.c | 1 + > > 3 files changed, 3 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h > > index 03b90cdc..652e5f3 100644 > > --- a/include/linux/vm_event_item.h > > +++ b/include/linux/vm_event_item.h > > @@ -29,6 +29,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, > > FOR_ALL_ZONES(PGSTEAL), > > 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 8b6da2b..e88138b 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -2154,6 +2154,7 @@ static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, > > goto out; > > > > /* Throttle */ > > + count_vm_event(PGSCAN_DIRECT_THROTTLE); > > do { > > schedule(); > > finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait); > > diff --git a/mm/vmstat.c b/mm/vmstat.c > > index a2b7344..5725387 100644 > > --- a/mm/vmstat.c > > +++ b/mm/vmstat.c > > @@ -911,6 +911,7 @@ const char * const vmstat_text[] = { > > TEXTS_FOR_ZONES("pgsteal") > > TEXTS_FOR_ZONES("pgscan_kswapd") > > TEXTS_FOR_ZONES("pgscan_direct") > > + "pgscan_direct_throttle", > > > > #ifdef CONFIG_NUMA > > "zone_reclaim_failed", > > I like this approach. Make the information available, but don't make a fuss > about it. > > Actually, I like the whole series - I'm really having to dig deep to find > anything to complain about :-) > > Feel free to put > Reviewed-by: NeilBrown <neilb@xxxxxxx> > against anything that I haven't commented on. > Thanks very much! -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>