[patch 23/23] SLUB: Add SlabReclaimable() to avoid repeated reclaim attempts

[Christoph Lameter]

Add a flag RECLAIMABLE to be set on slabs with a defragmentation method

Clear the flag if a reclaim action is not successful in reducing the
number of objects in a slab.

The reclaim flag is set again when all objeccts of the slab have been
allocated and it is removed from the partial lists.

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
---
 mm/slub.c |   20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2007-11-06 17:06:46.000000000 -0800
+++ linux-2.6/mm/slub.c	2007-11-06 17:07:54.000000000 -0800
@@ -102,6 +102,7 @@
 
 #define FROZEN (1 << PG_active)
 #define LOCKED (1 << PG_locked)
+#define RECLAIMABLE (1 << PG_dirty)
 
 #ifdef CONFIG_SLUB_DEBUG
 #define SLABDEBUG (1 << PG_error)
@@ -1100,6 +1101,8 @@ static noinline struct page *new_slab(st
 	if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
 			SLAB_STORE_USER | SLAB_TRACE))
 		state |= SLABDEBUG;
+	if (s->kick)
+		state |= RECLAIMABLE;
 
 	start = page_address(page);
 	page->end = start + 1;
@@ -1176,6 +1179,7 @@ static void discard_slab(struct kmem_cac
 
 	atomic_long_dec(&n->nr_slabs);
 	reset_page_mapcount(page);
+	page->flags &= ~RECLAIMABLE;
 	__ClearPageSlab(page);
 	free_slab(s, page);
 }
@@ -1408,8 +1412,11 @@ static void unfreeze_slab(struct kmem_ca
 
 		if (page->freelist != page->end)
 			add_partial(s, page, tail);
-		else
+		else {
 			add_full(s, page, state);
+			if (s->kick && !(state & RECLAIMABLE))
+				state |= RECLAIMABLE;
+		}
 		slab_unlock(page, state);
 
 	} else {
@@ -2633,7 +2640,7 @@ out:
  * Check if the given state is that of a reclaimable slab page.
  *
  * This is only true if this is indeed a slab page and if
- * the page has not been frozen.
+ * the page has not been frozen or marked as unreclaimable.
  */
 static inline int reclaimable_slab(unsigned long state)
 {
@@ -2643,7 +2650,7 @@ static inline int reclaimable_slab(unsig
 	if (state & FROZEN)
 		return 0;
 
-	return 1;
+	return state & RECLAIMABLE;
 }
 
  /*
@@ -2958,6 +2965,8 @@ out:
 	 * Check the result and unfreeze the slab
 	 */
 	leftover = page->inuse;
+	if (leftover)
+		state &= ~RECLAIMABLE;
 	unfreeze_slab(s, page, leftover > 0, state);
 	local_irq_restore(flags);
 	return leftover;
@@ -3012,6 +3021,11 @@ static unsigned long __kmem_cache_shrink
 		if (!state)
 			continue;
 
+		if (!(state & RECLAIMABLE)) {
+			slab_unlock(page, state);
+			continue;
+		}
+
 		if (page->inuse) {
 
 			list_move(&page->lru, &zaplist);

-- 
-
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