path: root/block
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authorJens Axboe <jens.axboe@oracle.com>2009-12-06 09:54:19 +0100
committerJens Axboe <jens.axboe@oracle.com>2009-12-06 09:54:19 +0100
commitbb729bc98c0f3e6a898d8730df3e2830bf68751a (patch)
treef2170f8f688a7c7f813168a6c8c757087934c094 /block
parent846954b0a32f4ae953e082eabd178e7a98dd2efd (diff)
cfq-iosched: use call_rcu() instead of doing grace period stall on queue exit
After the merge of the IO controller patches, booting on my megaraid box ran much slower. Vivek Goyal traced it down to megaraid discovery creating tons of devices, each suffering a grace period when they later kill that queue (if no device is found). So lets use call_rcu() to batch these deferred frees, instead of taking the grace period hit for each one. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
1 files changed, 8 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 78f4829895bd..3815f9789b6a 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -287,6 +287,7 @@ struct cfq_data {
/* List of cfq groups being managed on this device*/
struct hlist_head cfqg_list;
+ struct rcu_head rcu;
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
@@ -3601,6 +3602,11 @@ static void cfq_put_async_queues(struct cfq_data *cfqd)
+static void cfq_cfqd_free(struct rcu_head *head)
+ kfree(container_of(head, struct cfq_data, rcu));
static void cfq_exit_queue(struct elevator_queue *e)
struct cfq_data *cfqd = e->elevator_data;
@@ -3630,8 +3636,7 @@ static void cfq_exit_queue(struct elevator_queue *e)
/* Wait for cfqg->blkg->key accessors to exit their grace periods. */
- synchronize_rcu();
- kfree(cfqd);
+ call_rcu(&cfqd->rcu, cfq_cfqd_free);
static void *cfq_init_queue(struct request_queue *q)
@@ -3706,6 +3711,7 @@ static void *cfq_init_queue(struct request_queue *q)
cfqd->cfq_group_isolation = 0;
cfqd->hw_tag = -1;
cfqd->last_end_sync_rq = jiffies;
+ INIT_RCU_HEAD(&cfqd->rcu);
return cfqd;