[PATCH 5/7] mlocked-pages: add event counting with statistics

Lee Schermerhorn
2008-07-30T20:06:49Z

Fix to vmstat-mlocked-pages-statistics.patch

Define mlocked pages vm events in the mlocked pages
statistics patch. Makes for easier incremental patching.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

include/linux/vmstat.h | 4 ++++
mm/internal.h | 4 +++-
mm/mlock.c | 33 +++++++++++++++++++++++++--------
mm/vmstat.c | 4 ++++
4 files changed, 36 insertions(+), 9 deletions(-)

Index: linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/include/linux/vmstat.h 2008-07-30 13:26:08.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/include/linux/vmstat.h 2008-07-30 13:40:43.000000000 -0400
@@ -45,6 +45,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
UNEVICTABLE_PGCULLED, /* culled to noreclaim list */
UNEVICTABLE_PGSCANNED, /* scanned for reclaimability */
UNEVICTABLE_PGRESCUED, /* rescued from noreclaim list */
+ UNEVICTABLE_PGMLOCKED,
+ UNEVICTABLE_PGMUNLOCKED,
+ UNEVICTABLE_PGCLEARED, /* on COW, page truncate */
+ UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
#endif
NR_VM_EVENT_ITEMS
};
Index: linux-2.6.27-rc1-mmotm-30jul/mm/mlock.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/mlock.c 2008-07-30 13:36:17.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/mlock.c 2008-07-30 13:47:04.000000000 -0400
@@ -61,6 +61,7 @@ void __clear_page_mlock(struct page *pag
}

dec_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGCLEARED);
if (!isolate_lru_page(page)) {
putback_lru_page(page);
} else {
@@ -70,6 +71,9 @@ void __clear_page_mlock(struct page *pag
lru_add_drain_all();
if (!isolate_lru_page(page))
putback_lru_page(page);
+ else if (PageUnevictable(page))
+ count_vm_event(UNEVICTABLE_PGSTRANDED);
+
}
}

@@ -83,6 +87,7 @@ void mlock_vma_page(struct 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);
}
@@ -113,16 +118,28 @@ static void munlock_vma_page(struct page
if (TestClearPageMlocked(page)) {
dec_zone_page_state(page, NR_MLOCK);
if (!isolate_lru_page(page)) {
- try_to_munlock(page); /* maybe relock the 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);
}
- /*
- * 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.
- */
}
}

Index: linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/vmstat.c 2008-07-30 13:36:17.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/vmstat.c 2008-07-30 13:48:12.000000000 -0400
@@ -668,6 +668,10 @@ static const char * const vmstat_text[]
"unevictable_pgs_culled",
"unevictable_pgs_scanned",
"unevictable_pgs_rescued",
+ "unevictable_pgs_mlocked",
+ "unevictable_pgs_munlocked",
+ "unevictable_pgs_cleared",
+ "unevictable_pgs_stranded",
#endif
#endif
};
Index: linux-2.6.27-rc1-mmotm-30jul/mm/internal.h
===================================================================
--- linux-2.6.27-rc1-mmotm-30jul.orig/mm/internal.h 2008-07-30 13:36:17.000000000 -0400
+++ linux-2.6.27-rc1-mmotm-30jul/mm/internal.h 2008-07-30 13:46:31.000000000 -0400
@@ -101,8 +101,10 @@ static inline int is_mlocked_vma(struct
if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
return 0;

- if (!TestSetPageMlocked(page))
+ if (!TestSetPageMlocked(page)) {
inc_zone_page_state(page, NR_MLOCK);
+ count_vm_event(UNEVICTABLE_PGMLOCKED);
+ }
return 1;
}