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cfq-iosched: use call_rcu() instead of doing grace period stall on queue exit

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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>
This commit is contained in:
Jens Axboe 2009-12-06 09:54:19 +01:00
parent 846954b0a3
commit bb729bc98c
1 changed files with 8 additions and 2 deletions
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10
block/cfq-iosched.c
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@ -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)
cfq_put_queue(cfqd->async_idle_cfqq);
}
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)
cfq_shutdown_timer_wq(cfqd);
/* 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;
}