[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>

2 files changed, 3 insertions, 2 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 543f9e411563..eb42c1277023 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -47,6 +47,9 @@ struct zone_padding {
 #endif
 
 enum zone_stat_item {
+        NR_FILE_MAPPED, /* mapped into pagetables.
+                           only modified from process context */
+
         NR_VM_ZONE_STAT_ITEMS };
 
 struct per_cpu_pages {
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 3fd5c11e544a..8ab8229523e6 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -26,8 +26,6 @@ struct page_state {
         unsigned long nr_writeback;     /* Pages under writeback */
         unsigned long nr_unstable;      /* NFS unstable pages */
         unsigned long nr_page_table_pages;/* Pages used for pagetables */
-        unsigned long nr_mapped;        /* mapped into pagetables.
-                                         * only modified from process context */
         unsigned long nr_slab;          /* In slab */
 #define GET_PAGE_STATE_LAST nr_slab