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authorJens Axboe <jens.axboe@oracle.com>2007-04-24 21:23:53 +0200
committerJens Axboe <axboe@nelson.home.kernel.dk>2007-04-30 09:01:23 +0200
commit597bc485d6906359ad667fc8ead5e5f0ede03a0a (patch)
treef59303df8b17f51781adedc6320c9a14130a650e /block/cfq-iosched.c
parent4e521c27eee33cebd618c26649e2c93803004647 (diff)
downloadconfigs-597bc485d6906359ad667fc8ead5e5f0ede03a0a.tar.gz
cfq-iosched: speedup cic rb lookup
We often lookup the same queue many times in succession, so cache the last looked up queue to avoid browsing the rbtree. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/cfq-iosched.c')
-rw-r--r--block/cfq-iosched.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 94f53a1f467..64df3fa303b 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1165,6 +1165,8 @@ static void cfq_free_io_context(struct io_context *ioc)
struct rb_node *n;
int freed = 0;
+ ioc->ioc_data = NULL;
+
while ((n = rb_first(&ioc->cic_root)) != NULL) {
__cic = rb_entry(n, struct cfq_io_context, rb_node);
rb_erase(&__cic->rb_node, &ioc->cic_root);
@@ -1228,10 +1230,11 @@ static void cfq_exit_io_context(struct io_context *ioc)
struct cfq_io_context *__cic;
struct rb_node *n;
+ ioc->ioc_data = NULL;
+
/*
* put the reference this task is holding to the various queues
*/
-
n = rb_first(&ioc->cic_root);
while (n != NULL) {
__cic = rb_entry(n, struct cfq_io_context, rb_node);
@@ -1415,6 +1418,10 @@ static void
cfq_drop_dead_cic(struct io_context *ioc, struct cfq_io_context *cic)
{
WARN_ON(!list_empty(&cic->queue_list));
+
+ if (ioc->ioc_data == cic)
+ ioc->ioc_data = NULL;
+
rb_erase(&cic->rb_node, &ioc->cic_root);
kmem_cache_free(cfq_ioc_pool, cic);
elv_ioc_count_dec(ioc_count);
@@ -1430,6 +1437,13 @@ cfq_cic_rb_lookup(struct cfq_data *cfqd, struct io_context *ioc)
if (unlikely(!ioc))
return NULL;
+ /*
+ * we maintain a last-hit cache, to avoid browsing over the tree
+ */
+ cic = ioc->ioc_data;
+ if (cic && cic->key == cfqd)
+ return cic;
+
restart:
n = ioc->cic_root.rb_node;
while (n) {
@@ -1445,8 +1459,10 @@ restart:
n = n->rb_left;
else if (key > k)
n = n->rb_right;
- else
+ else {
+ ioc->ioc_data = cic;
return cic;
+ }
}
return NULL;