vmstat: mlocked pages statistics
Add NR_MLOCK zone page state, which provides a (conservative) count of
mlocked pages (actually, the number of mlocked pages moved off the LRU).
Reworked by lts to fit in with the modified mlock page support in the
Reclaim Scalability series.
[kosaki.motohiro@jp.fujitsu.com: fix incorrect Mlocked field of /proc/meminfo]
[lee.schermerhorn@hp.com: mlocked-pages: add event counting with statistics]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/internal.h b/mm/internal.h
index 48e32f7..1cfbf2e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -101,7 +101,10 @@
if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
return 0;
- SetPageMlocked(page);
+ if (!TestSetPageMlocked(page)) {
+ inc_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGMLOCKED);
+ }
return 1;
}
@@ -128,12 +131,19 @@
/*
* mlock_migrate_page - called only from migrate_page_copy() to
- * migrate the Mlocked page flag
+ * migrate the Mlocked page flag; update statistics.
*/
static inline void mlock_migrate_page(struct page *newpage, struct page *page)
{
- if (TestClearPageMlocked(page))
+ if (TestClearPageMlocked(page)) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ __dec_zone_page_state(page, NR_MLOCK);
SetPageMlocked(newpage);
+ __inc_zone_page_state(newpage, NR_MLOCK);
+ local_irq_restore(flags);
+ }
}
diff --git a/mm/mlock.c b/mm/mlock.c
index 8b47835..bce1b22 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -60,6 +60,8 @@
return;
}
+ dec_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGCLEARED);
if (!isolate_lru_page(page)) {
putback_lru_page(page);
} else {
@@ -69,6 +71,9 @@
lru_add_drain_all();
if (!isolate_lru_page(page))
putback_lru_page(page);
+ else if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+
}
}
@@ -80,8 +85,12 @@
{
BUG_ON(!PageLocked(page));
- if (!TestSetPageMlocked(page) && !isolate_lru_page(page))
- putback_lru_page(page);
+ if (!TestSetPageMlocked(page)) {
+ inc_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGMLOCKED);
+ if (!isolate_lru_page(page))
+ putback_lru_page(page);
+ }
}
/*
@@ -106,9 +115,31 @@
{
BUG_ON(!PageLocked(page));
- if (TestClearPageMlocked(page) && !isolate_lru_page(page)) {
- try_to_munlock(page);
- putback_lru_page(page);
+ if (TestClearPageMlocked(page)) {
+ dec_zone_page_state(page, NR_MLOCK);
+ if (!isolate_lru_page(page)) {
+ int ret = try_to_munlock(page);
+ /*
+ * did try_to_unlock() succeed or punt?
+ */
+ if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN)
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
+ putback_lru_page(page);
+ } else {
+ /*
+ * We lost the race. let try_to_unmap() deal
+ * with it. At least we get the page state and
+ * mlock stats right. However, page is still on
+ * the noreclaim list. We'll fix that up when
+ * the page is eventually freed or we scan the
+ * noreclaim list.
+ */
+ if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+ else
+ count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+ }
}
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6db2f63..9e28abc 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -625,6 +625,7 @@
"nr_active_file",
#ifdef CONFIG_UNEVICTABLE_LRU
"nr_unevictable",
+ "nr_mlock",
#endif
"nr_anon_pages",
"nr_mapped",
@@ -684,6 +685,10 @@
"unevictable_pgs_culled",
"unevictable_pgs_scanned",
"unevictable_pgs_rescued",
+ "unevictable_pgs_mlocked",
+ "unevictable_pgs_munlocked",
+ "unevictable_pgs_cleared",
+ "unevictable_pgs_stranded",
#endif
#endif
};