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authorAndreas Gruenbacher <agruen@suse.de>2010-08-16 19:05:23 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2010-08-18 06:24:41 -0400
commit3a48ee8a4ad26c3a538b6fc11a86a8f80c3dce18 (patch)
tree3e89deaa14c8d72c7484f61c2babc5755a9e991e /fs/mbcache.c
parent3b6036d148bad5bb7928b021a49bb9e395361084 (diff)
downloadlinux-stericsson-3a48ee8a4ad26c3a538b6fc11a86a8f80c3dce18.tar.gz
mbcache: Limit the maximum number of cache entries
Limit the maximum number of mb_cache entries depending on the number of hash buckets: if the only limit to the number of cache entries is the available memory the hash chains can grow very long, taking a long time to search. At least partially solves https://bugzilla.lustre.org/show_bug.cgi?id=22771. Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/mbcache.c')
-rw-r--r--fs/mbcache.c30
1 files changed, 24 insertions, 6 deletions
diff --git a/fs/mbcache.c b/fs/mbcache.c
index cf4e6cdfd15b..93444747237b 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -80,6 +80,7 @@ struct mb_cache {
struct list_head c_cache_list;
const char *c_name;
atomic_t c_entry_count;
+ int c_max_entries;
int c_bucket_bits;
struct kmem_cache *c_entry_cache;
struct list_head *c_block_hash;
@@ -243,6 +244,12 @@ mb_cache_create(const char *name, int bucket_bits)
if (!cache->c_entry_cache)
goto fail2;
+ /*
+ * Set an upper limit on the number of cache entries so that the hash
+ * chains won't grow too long.
+ */
+ cache->c_max_entries = bucket_count << 4;
+
spin_lock(&mb_cache_spinlock);
list_add(&cache->c_cache_list, &mb_cache_list);
spin_unlock(&mb_cache_spinlock);
@@ -333,7 +340,6 @@ mb_cache_destroy(struct mb_cache *cache)
kfree(cache);
}
-
/*
* mb_cache_entry_alloc()
*
@@ -345,17 +351,29 @@ mb_cache_destroy(struct mb_cache *cache)
struct mb_cache_entry *
mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
{
- struct mb_cache_entry *ce;
-
- ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
- if (ce) {
+ struct mb_cache_entry *ce = NULL;
+
+ if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) {
+ spin_lock(&mb_cache_spinlock);
+ if (!list_empty(&mb_cache_lru_list)) {
+ ce = list_entry(mb_cache_lru_list.next,
+ struct mb_cache_entry, e_lru_list);
+ list_del_init(&ce->e_lru_list);
+ __mb_cache_entry_unhash(ce);
+ }
+ spin_unlock(&mb_cache_spinlock);
+ }
+ if (!ce) {
+ ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
+ if (!ce)
+ return NULL;
atomic_inc(&cache->c_entry_count);
INIT_LIST_HEAD(&ce->e_lru_list);
INIT_LIST_HEAD(&ce->e_block_list);
ce->e_cache = cache;
- ce->e_used = 1 + MB_CACHE_WRITER;
ce->e_queued = 0;
}
+ ce->e_used = 1 + MB_CACHE_WRITER;
return ce;
}