[PATCH] zoned vm counters: convert nr_mapped to per zone counter

nr_mapped is important because it allows a determination of how many pages of
a zone are not mapped, which would allow a more efficient means of determining
when we need to reclaim memory in a zone.

We take the nr_mapped field out of the page state structure and define a new
per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off
from NR_MAPPED in the next patch).

We replace the use of nr_mapped in various kernel locations.  This avoids the
looping over all processors in try_to_free_pages(), writeback, reclaim (swap +
zone reclaim).

[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index eeacb0d695c3..d2caf7471cf1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -990,7 +990,7 @@ unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
         }
 
         for (priority = DEF_PRIORITY; priority >= 0; priority--) {
-                sc.nr_mapped = read_page_state(nr_mapped);
+                sc.nr_mapped = global_page_state(NR_FILE_MAPPED);
                 sc.nr_scanned = 0;
                 if (!priority)
                         disable_swap_token();
@@ -1075,7 +1075,7 @@ loop_again:
         total_scanned = 0;
         nr_reclaimed = 0;
         sc.may_writepage = !laptop_mode;
-        sc.nr_mapped = read_page_state(nr_mapped);
+        sc.nr_mapped = global_page_state(NR_FILE_MAPPED);
 
         inc_page_state(pageoutrun);
 
@@ -1407,7 +1407,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
                 for (prio = DEF_PRIORITY; prio >= 0; prio--) {
                         unsigned long nr_to_scan = nr_pages - ret;
 
-                        sc.nr_mapped = read_page_state(nr_mapped);
+                        sc.nr_mapped = global_page_state(NR_FILE_MAPPED);
                         sc.nr_scanned = 0;
 
                         ret += shrink_all_zones(nr_to_scan, prio, pass, &sc);
@@ -1548,7 +1548,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
         struct scan_control sc = {
                 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
                 .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
-                .nr_mapped = read_page_state(nr_mapped),
+                .nr_mapped = global_page_state(NR_FILE_MAPPED),
                 .swap_cluster_max = max_t(unsigned long, nr_pages,
                                         SWAP_CLUSTER_MAX),
                 .gfp_mask = gfp_mask,