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cfq: async queue allocation per priority

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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>
This commit is contained in:
Vasily Tarasov 2007-07-20 10:06:38 +02:00 committed by Jens Axboe
parent 9a79b22741
commit c2dea2d1fd
2 changed files with 52 additions and 12 deletions
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56
block/cfq-iosched.c
View File

@ -92,7 +92,11 @@ struct cfq_data {
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 @@ out:
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 @@ static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
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 @@ static void cfq_exit_queue(elevator_t *e)
__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);

8
include/linux/ioprio.h
View File

@ -53,6 +53,14 @@ static inline int task_ioprio(struct task_struct *task)
return IOPRIO_NORM;
}
static inline int task_ioprio_class(struct task_struct *task)
{
if (ioprio_valid(task->ioprio))
return IOPRIO_PRIO_CLASS(task->ioprio);
return IOPRIO_CLASS_BE;
}
static inline int task_nice_ioprio(struct task_struct *task)
{
return (task_nice(task) + 20) / 5;