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Re: slablru for 2.5.32-mm1
On September 2, 2002 01:26 am, Andrew Morton wrote:
> Ed, this code can be sped up a bit, I think. We can make
> kmem_count_page() return a boolean back to shrink_cache(), telling it
> whether it needs to call kmem_do_prunes() at all. Often, there won't
> be any work to do in there, and taking that semaphore can be quite
> costly.
>
> The code as-is will even run kmem_do_prunes() when we're examining
> ZONE_HIGHMEM, which certainly won't have any slab pages. This boolean
> will fix that too.
How about this? I have modified things so we only try for the sem if there
is work to do. It also always uses a down_trylock - if we cannot do the prune
now later is ok too...
Lightly tested.
Comments
Ed
-----------
# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.531 -> 1.533
# mm/slab.c 1.28 -> 1.30
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/09/02 ed@oscar.et.ca 1.532
# optimization. lets only take the sem if we have work to do.
# --------------------------------------------
# 02/09/02 ed@oscar.et.ca 1.533
# more optimizations and a correction
# --------------------------------------------
#
diff -Nru a/mm/slab.c b/mm/slab.c
--- a/mm/slab.c Mon Sep 2 10:54:33 2002
+++ b/mm/slab.c Mon Sep 2 10:54:33 2002
@@ -403,6 +403,9 @@
/* Place maintainer for reaping. */
static kmem_cache_t *clock_searchp = &cache_cache;
+static int pruner_flag;
+#define PRUNE_GATE 0
+
#define cache_chain (cache_cache.next)
#ifdef CONFIG_SMP
@@ -427,6 +430,8 @@
spin_lock_irq(&cachep->spinlock);
if (cachep->pruner != NULL) {
cachep->count += slabp->inuse;
+ if (cachep->count)
+ set_bit(PRUNE_GATE, &pruner_flag);
ret = !slabp->inuse;
} else
ret = !ref && !slabp->inuse;
@@ -441,11 +446,13 @@
struct list_head *p;
int nr;
- if (gfp_mask & __GFP_WAIT)
- down(&cache_chain_sem);
- else
- if (down_trylock(&cache_chain_sem))
- return 0;
+ if (!test_and_clear_bit(PRUNE_GATE, &pruner_flag))
+ return 0;
+
+ if (down_trylock(&cache_chain_sem)) {
+ set_bit(PRUNE_GATE, &pruner_flag);
+ return 0;
+ }
list_for_each(p,&cache_chain) {
kmem_cache_t *cachep = list_entry(p, kmem_cache_t, next);
-----------
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