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Subject[patch 06/19] slub: Add KICKABLE to avoid repeated kick() attempts
Add a flag KICKABLE to be set on slabs with a defragmentation method

Clear the flag if a kick action is not successful in reducing the
number of objects in a slab. This will avoid future attempts to
kick objects out.

The KICKABLE flag is set again when all objects of the slab have been
allocated (Occurs during removal of a slab from the partial lists).

Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

---
mm/slub.c | 35 ++++++++++++++++++++++++++++++++---
1 file changed, 32 insertions(+), 3 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2008-07-31 12:19:28.000000000 -0500
+++ linux-2.6/mm/slub.c 2008-07-31 12:19:39.000000000 -0500
@@ -1130,6 +1130,9 @@
SLAB_STORE_USER | SLAB_TRACE))
__SetPageSlubDebug(page);

+ if (s->kick)
+ __SetPageSlubKickable(page);
+
start = page_address(page);

if (unlikely(s->flags & SLAB_POISON))
@@ -1170,6 +1173,7 @@
NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
-pages);

+ __ClearPageSlubKickable(page);
__ClearPageSlab(page);
reset_page_mapcount(page);
__free_pages(page, order);
@@ -1380,6 +1384,8 @@
if (SLABDEBUG && PageSlubDebug(page) &&
(s->flags & SLAB_STORE_USER))
add_full(n, page);
+ if (s->kick)
+ __SetPageSlubKickable(page);
}
slab_unlock(page);
} else {
@@ -2795,12 +2801,12 @@
slab_lock(page);

BUG_ON(!PageSlab(page)); /* Must be s slab page */
- BUG_ON(!SlabFrozen(page)); /* Slab must have been frozen earlier */
+ BUG_ON(!PageSlubFrozen(page)); /* Slab must have been frozen earlier */

s = page->slab;
objects = page->objects;
map = scratch + objects * sizeof(void **);
- if (!page->inuse || !s->kick)
+ if (!page->inuse || !s->kick || !PageSlubKickable(page))
goto out;

/* Determine used objects */
@@ -2838,6 +2844,9 @@
* Check the result and unfreeze the slab
*/
leftover = page->inuse;
+ if (leftover)
+ /* Unsuccessful reclaim. Avoid future reclaim attempts. */
+ __ClearPageSlubKickable(page);
unfreeze_slab(s, page, leftover > 0);
local_irq_restore(flags);
return leftover;
@@ -2899,17 +2908,21 @@
continue;

if (page->inuse) {
- if (page->inuse * 100 >=
+ if (!PageSlubKickable(page) || page->inuse * 100 >=
s->defrag_ratio * page->objects) {
slab_unlock(page);
- /* Slab contains enough objects */
+ /*
+ * Slab contains enough objects
+ * or we alrady tried reclaim before and
+ * it failed. Skip this one.
+ */
continue;
}

list_move(&page->lru, &zaplist);
if (s->kick) {
n->nr_partial--;
- SetSlabFrozen(page);
+ __SetPageSlubFrozen(page);
}
slab_unlock(page);
} else {
Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h 2008-07-31 12:19:25.000000000 -0500
+++ linux-2.6/include/linux/page-flags.h 2008-07-31 12:19:28.000000000 -0500
@@ -112,6 +112,7 @@
/* SLUB */
PG_slub_frozen = PG_active,
PG_slub_debug = PG_error,
+ PG_slub_kickable = PG_dirty,
};

#ifndef __GENERATING_BOUNDS_H
@@ -182,6 +183,7 @@

__PAGEFLAG(SlubFrozen, slub_frozen)
__PAGEFLAG(SlubDebug, slub_debug)
+__PAGEFLAG(SlubKickable, slub_kickable)

/*
* Only test-and-set exist for PG_writeback. The unconditional operators are
--


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