cfq: async queue allocation per priority
If we have two processes with different ioprio_class, but the same
ioprio_data, their async requests will fall into the same queue. I guess
such behavior is not expected, because it's not right to put real-time
requests and best-effort requests in the same queue.
The attached patch fixes the problem by introducing additional *cfqq
fields on cfqd, pointing to per-(class,priority) async queues.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9755a3c..bc7190e 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -92,7 +92,11 @@
struct cfq_queue *active_queue;
struct cfq_io_context *active_cic;
- struct cfq_queue *async_cfqq[IOPRIO_BE_NR];
+ /*
+ * async queue for each priority case
+ */
+ struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
+ struct cfq_queue *async_idle_cfqq;
struct timer_list idle_class_timer;
@@ -1414,24 +1418,44 @@
return cfqq;
}
+static struct cfq_queue **
+cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
+{
+ switch(ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &cfqd->async_cfqq[0][ioprio];
+ case IOPRIO_CLASS_BE:
+ return &cfqd->async_cfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &cfqd->async_idle_cfqq;
+ default:
+ BUG();
+ }
+}
+
static struct cfq_queue *
cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
gfp_t gfp_mask)
{
const int ioprio = task_ioprio(tsk);
+ const int ioprio_class = task_ioprio_class(tsk);
+ struct cfq_queue **async_cfqq = NULL;
struct cfq_queue *cfqq = NULL;
- if (!is_sync)
- cfqq = cfqd->async_cfqq[ioprio];
+ if (!is_sync) {
+ async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
+ cfqq = *async_cfqq;
+ }
+
if (!cfqq)
cfqq = cfq_find_alloc_queue(cfqd, is_sync, tsk, gfp_mask);
/*
* pin the queue now that it's allocated, scheduler exit will prune it
*/
- if (!is_sync && !cfqd->async_cfqq[ioprio]) {
+ if (!is_sync && !(*async_cfqq)) {
atomic_inc(&cfqq->ref);
- cfqd->async_cfqq[ioprio] = cfqq;
+ *async_cfqq = cfqq;
}
atomic_inc(&cfqq->ref);
@@ -2042,11 +2066,24 @@
blk_sync_queue(cfqd->queue);
}
+static void cfq_put_async_queues(struct cfq_data *cfqd)
+{
+ int i;
+
+ for (i = 0; i < IOPRIO_BE_NR; i++) {
+ if (cfqd->async_cfqq[0][i])
+ cfq_put_queue(cfqd->async_cfqq[0][i]);
+ if (cfqd->async_cfqq[1][i])
+ cfq_put_queue(cfqd->async_cfqq[1][i]);
+ if (cfqd->async_idle_cfqq)
+ cfq_put_queue(cfqd->async_idle_cfqq);
+ }
+}
+
static void cfq_exit_queue(elevator_t *e)
{
struct cfq_data *cfqd = e->elevator_data;
request_queue_t *q = cfqd->queue;
- int i;
cfq_shutdown_timer_wq(cfqd);
@@ -2063,12 +2100,7 @@
__cfq_exit_single_io_context(cfqd, cic);
}
- /*
- * Put the async queues
- */
- for (i = 0; i < IOPRIO_BE_NR; i++)
- if (cfqd->async_cfqq[i])
- cfq_put_queue(cfqd->async_cfqq[i]);
+ cfq_put_async_queues(cfqd);
spin_unlock_irq(q->queue_lock);