[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>

10 files changed, 16 insertions, 17 deletions

diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c
index 2889567e21a..f85f1a40e5c 100644
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -61,7 +61,7 @@ void show_mem(void)
         get_page_state(&ps);
         printk(KERN_INFO "%lu pages dirty\n", ps.nr_dirty);
         printk(KERN_INFO "%lu pages writeback\n", ps.nr_writeback);
-        printk(KERN_INFO "%lu pages mapped\n", ps.nr_mapped);
+        printk(KERN_INFO "%lu pages mapped\n", global_page_state(NR_FILE_MAPPED));
         printk(KERN_INFO "%lu pages slab\n", ps.nr_slab);
         printk(KERN_INFO "%lu pages pagetables\n", ps.nr_page_table_pages);
 }
diff --git a/drivers/base/node.c b/drivers/base/node.c
index eae2bdc183b..8b1232320a9 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -54,8 +54,6 @@ static ssize_t node_read_meminfo(struct sys_device * dev, char * buf)
                 ps.nr_dirty = 0;
         if ((long)ps.nr_writeback < 0)
                 ps.nr_writeback = 0;
-        if ((long)ps.nr_mapped < 0)
-                ps.nr_mapped = 0;
         if ((long)ps.nr_slab < 0)
                 ps.nr_slab = 0;
 
@@ -84,7 +82,7 @@ static ssize_t node_read_meminfo(struct sys_device * dev, char * buf)
                        nid, K(i.freeram - i.freehigh),
                        nid, K(ps.nr_dirty),
                        nid, K(ps.nr_writeback),
-                       nid, K(ps.nr_mapped),
+                       nid, K(node_page_state(nid, NR_FILE_MAPPED)),
                        nid, K(ps.nr_slab));
         n += hugetlb_report_node_meminfo(nid, buf + n);
         return n;
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 5c10ea15742..bc7d9abca74 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -190,7 +190,7 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
                 K(i.freeswap),
                 K(ps.nr_dirty),
                 K(ps.nr_writeback),
-                K(ps.nr_mapped),
+                K(global_page_state(NR_FILE_MAPPED)),
                 K(ps.nr_slab),
                 K(allowed),
                 K(committed),
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 543f9e41156..eb42c127702 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 3fd5c11e544..8ab8229523e 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
 
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4ec7026c7ba..60c7244c42e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -111,7 +111,7 @@ static void get_writeback_state(struct writeback_state *wbs)
 {
         wbs->nr_dirty = read_page_state(nr_dirty);
         wbs->nr_unstable = read_page_state(nr_unstable);
-        wbs->nr_mapped = read_page_state(nr_mapped);
+        wbs->nr_mapped = global_page_state(NR_FILE_MAPPED);
         wbs->nr_writeback = read_page_state(nr_writeback);
 }
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3a877fecc30..04dd2b01b2b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1319,7 +1319,7 @@ void show_free_areas(void)
                 ps.nr_unstable,
                 nr_free_pages(),
                 ps.nr_slab,
-                ps.nr_mapped,
+                global_page_state(NR_FILE_MAPPED),
                 ps.nr_page_table_pages);
 
         for_each_zone(zone) {
diff --git a/mm/rmap.c b/mm/rmap.c
index e76909e880c..af5e9808e65 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -455,7 +455,7 @@ static void __page_set_anon_rmap(struct page *page,
          * nr_mapped state can be updated without turning off
          * interrupts because it is not modified via interrupt.
          */
-        __inc_page_state(nr_mapped);
+        __inc_zone_page_state(page, NR_FILE_MAPPED);
 }
 
 /**
@@ -499,7 +499,7 @@ void page_add_new_anon_rmap(struct page *page,
 void page_add_file_rmap(struct page *page)
 {
         if (atomic_inc_and_test(&page->_mapcount))
-                __inc_page_state(nr_mapped);
+                __inc_zone_page_state(page, NR_FILE_MAPPED);
 }
 
 /**
@@ -531,7 +531,7 @@ void page_remove_rmap(struct page *page)
                  */
                 if (page_test_and_clear_dirty(page))
                         set_page_dirty(page);
-                __dec_page_state(nr_mapped);
+                __dec_zone_page_state(page, NR_FILE_MAPPED);
         }
 }
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eeacb0d695c..d2caf7471cf 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,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 210f9bbbb04..4800091c129 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -401,13 +401,13 @@ struct seq_operations fragmentation_op = {
 
 static char *vmstat_text[] = {
         /* Zoned VM counters */
+        "nr_mapped",
 
         /* Page state */
         "nr_dirty",
         "nr_writeback",
         "nr_unstable",
         "nr_page_table_pages",
-        "nr_mapped",
         "nr_slab",
 
         "pgpgin",