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Subject[PATCH -mm 22/25] Noreclaim and Mlocked pages vm events
From:  Lee Schermerhorn <lee.schermerhorn@hp.com>

Against: 2.6.26-rc2-mm1

Add some event counters to vmstats for testing noreclaim/mlock.
Some of these might be interesting enough to keep around.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>

---
include/linux/vmstat.h | 11 +++++++++++
mm/internal.h | 4 +++-
mm/mlock.c | 33 +++++++++++++++++++++++++--------
mm/vmscan.c | 16 +++++++++++++++-
mm/vmstat.c | 12 ++++++++++++
5 files changed, 66 insertions(+), 10 deletions(-)

Index: linux-2.6.26-rc2-mm1/include/linux/vmstat.h
===================================================================
--- linux-2.6.26-rc2-mm1.orig/include/linux/vmstat.h 2008-05-23 14:21:34.000000000 -0400
+++ linux-2.6.26-rc2-mm1/include/linux/vmstat.h 2008-06-06 16:06:48.000000000 -0400
@@ -41,6 +41,17 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
#ifdef CONFIG_HUGETLB_PAGE
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
#endif
+#ifdef CONFIG_NORECLAIM_LRU
+ NORECL_PGCULLED, /* culled to noreclaim list */
+ NORECL_PGSCANNED, /* scanned for reclaimability */
+ NORECL_PGRESCUED, /* rescued from noreclaim list */
+#ifdef CONFIG_NORECLAIM_MLOCK
+ NORECL_PGMLOCKED,
+ NORECL_PGMUNLOCKED,
+ NORECL_PGCLEARED,
+ NORECL_PGSTRANDED, /* unable to isolate on unlock */
+#endif
+#endif
NR_VM_EVENT_ITEMS
};

Index: linux-2.6.26-rc2-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.26-rc2-mm1.orig/mm/vmscan.c 2008-06-06 16:06:28.000000000 -0400
+++ linux-2.6.26-rc2-mm1/mm/vmscan.c 2008-06-06 16:06:48.000000000 -0400
@@ -453,12 +453,13 @@ int putback_lru_page(struct page *page)
{
int lru;
int ret = 1;
+ int was_nonreclaimable;

VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(PageLRU(page));

lru = !!TestClearPageActive(page);
- ClearPageNoreclaim(page); /* for page_reclaimable() */
+ was_nonreclaimable = TestClearPageNoreclaim(page);

if (unlikely(!page->mapping)) {
/*
@@ -478,6 +479,10 @@ int putback_lru_page(struct page *page)
lru += page_file_cache(page);
lru_cache_add_lru(page, lru);
mem_cgroup_move_lists(page, lru);
+#ifdef CONFIG_NORECLAIM_LRU
+ if (was_nonreclaimable)
+ count_vm_event(NORECL_PGRESCUED);
+#endif
} else {
/*
* Put non-reclaimable pages directly on zone's noreclaim
@@ -485,6 +490,10 @@ int putback_lru_page(struct page *page)
*/
add_page_to_noreclaim_list(page);
mem_cgroup_move_lists(page, LRU_NORECLAIM);
+#ifdef CONFIG_NORECLAIM_LRU
+ if (!was_nonreclaimable)
+ count_vm_event(NORECL_PGCULLED);
+#endif
}

put_page(page); /* drop ref from isolate */
@@ -2366,6 +2375,7 @@ static void check_move_noreclaim_page(st
__dec_zone_state(zone, NR_NORECLAIM);
list_move(&page->lru, &zone->list[l]);
__inc_zone_state(zone, NR_INACTIVE_ANON + l);
+ __count_vm_event(NORECL_PGRESCUED);
} else {
/*
* rotate noreclaim list
@@ -2397,6 +2407,7 @@ void scan_mapping_noreclaim_pages(struct
while (next < end &&
pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
int i;
+ int pg_scanned = 0;

zone = NULL;

@@ -2405,6 +2416,7 @@ void scan_mapping_noreclaim_pages(struct
pgoff_t page_index = page->index;
struct zone *pagezone = page_zone(page);

+ pg_scanned++;
if (page_index > next)
next = page_index;
next++;
@@ -2435,6 +2447,8 @@ void scan_mapping_noreclaim_pages(struct
if (zone)
spin_unlock_irq(&zone->lru_lock);
pagevec_release(&pvec);
+
+ count_vm_events(NORECL_PGSCANNED, pg_scanned);
}

}
Index: linux-2.6.26-rc2-mm1/mm/vmstat.c
===================================================================
--- linux-2.6.26-rc2-mm1.orig/mm/vmstat.c 2008-06-06 16:06:38.000000000 -0400
+++ linux-2.6.26-rc2-mm1/mm/vmstat.c 2008-06-06 16:06:48.000000000 -0400
@@ -759,6 +759,18 @@ static const char * const vmstat_text[]
"htlb_buddy_alloc_success",
"htlb_buddy_alloc_fail",
#endif
+
+#ifdef CONFIG_NORECLAIM_LRU
+ "noreclaim_pgs_culled",
+ "noreclaim_pgs_scanned",
+ "noreclaim_pgs_rescued",
+#ifdef CONFIG_NORECLAIM_MLOCK
+ "noreclaim_pgs_mlocked",
+ "noreclaim_pgs_munlocked",
+ "noreclaim_pgs_cleared",
+ "noreclaim_pgs_stranded",
+#endif
+#endif
#endif
};

Index: linux-2.6.26-rc2-mm1/mm/mlock.c
===================================================================
--- linux-2.6.26-rc2-mm1.orig/mm/mlock.c 2008-06-06 16:06:38.000000000 -0400
+++ linux-2.6.26-rc2-mm1/mm/mlock.c 2008-06-06 16:06:48.000000000 -0400
@@ -18,6 +18,7 @@
#include <linux/rmap.h>
#include <linux/mmzone.h>
#include <linux/hugetlb.h>
+#include <linux/vmstat.h>

#include "internal.h"

@@ -57,6 +58,7 @@ void __clear_page_mlock(struct page *pag
VM_BUG_ON(!PageLocked(page)); /* for LRU islolate/putback */

dec_zone_page_state(page, NR_MLOCK);
+ count_vm_event(NORECL_PGCLEARED);
if (!isolate_lru_page(page)) {
putback_lru_page(page);
} else {
@@ -66,6 +68,8 @@ void __clear_page_mlock(struct page *pag
lru_add_drain_all();
if (!isolate_lru_page(page))
putback_lru_page(page);
+ else if (PageNoreclaim(page))
+ count_vm_event(NORECL_PGSTRANDED);
}
}

@@ -79,6 +83,7 @@ void mlock_vma_page(struct page *page)

if (!TestSetPageMlocked(page)) {
inc_zone_page_state(page, NR_MLOCK);
+ count_vm_event(NORECL_PGMLOCKED);
if (!isolate_lru_page(page))
putback_lru_page(page);
}
@@ -109,16 +114,28 @@ static void munlock_vma_page(struct page
if (TestClearPageMlocked(page)) {
dec_zone_page_state(page, NR_MLOCK);
if (!isolate_lru_page(page)) {
- try_to_unlock(page); /* maybe relock the page */
+ int ret = try_to_unlock(page);
+ /*
+ * did try_to_unlock() succeed or punt?
+ */
+ if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN)
+ count_vm_event(NORECL_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 (PageNoreclaim(page))
+ count_vm_event(NORECL_PGSTRANDED);
+ else
+ count_vm_event(NORECL_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-2.6.26-rc2-mm1/mm/internal.h
===================================================================
--- linux-2.6.26-rc2-mm1.orig/mm/internal.h 2008-06-06 16:06:38.000000000 -0400
+++ linux-2.6.26-rc2-mm1/mm/internal.h 2008-06-06 16:06:48.000000000 -0400
@@ -107,8 +107,10 @@ 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(NORECL_PGMLOCKED);
+ }
return 1;
}

--
All Rights Reversed



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