[PATCH] vm: add per-zone writeout counter

The VM is supposed to minimise the number of pages which get written off the
LRU (for IO scheduling efficiency, and for high reclaim-success rates).  But
we don't actually have a clear way of showing how true this is.

So add `nr_vmscan_write' to /proc/vmstat and /proc/zoneinfo - the number of
pages which have been written by the vm scanner in this zone and globally.

Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7fa1cbe9fa7a..1b0680cd84d2 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -58,6 +58,7 @@ enum zone_stat_item {
         NR_WRITEBACK,
         NR_UNSTABLE_NFS,        /* NFS unstable pages */
         NR_BOUNCE,
+        NR_VMSCAN_WRITE,
 #ifdef CONFIG_NUMA
         NUMA_HIT,               /* allocated in intended node */
         NUMA_MISS,              /* allocated in non intended node */