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Commit 6d63c275 authored by Jens Axboe's avatar Jens Axboe
Browse files

cfq-iosched: make io priorities inherit CPU scheduling class as well as nice 



We currently set all processes to the best-effort scheduling class,
regardless of what CPU scheduling class they belong to. Improve that
so that we correctly track idle and rt scheduling classes as well.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent dbaf2c00

block/cfq-iosched.c

+2 −2
Original line number Diff line number Diff line
@@ -1303,10 +1303,10 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) 
		printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);

	case IOPRIO_CLASS_NONE:

		/*

		 * no prio set, place us in the middle of the BE classes

		 * no prio set, inherit CPU scheduling settings

		 */

		cfqq->ioprio = task_nice_ioprio(tsk);

		cfqq->ioprio_class = IOPRIO_CLASS_BE;

		cfqq->ioprio_class = task_nice_ioclass(tsk);

		break;

	case IOPRIO_CLASS_RT:

		cfqq->ioprio = task_ioprio(ioc);

include/linux/ioprio.h

+14 −0
Original line number Diff line number Diff line
@@ -67,6 +67,20 @@ static inline int task_nice_ioprio(struct task_struct *task) 
	return (task_nice(task) + 20) / 5;

}



/*

 * This is for the case where the task hasn't asked for a specific IO class.

 * Check for idle and rt task process, and return appropriate IO class.

 */

static inline int task_nice_ioclass(struct task_struct *task)

{

	if (task->policy == SCHED_IDLE)

		return IOPRIO_CLASS_IDLE;

	else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)

		return IOPRIO_CLASS_RT;

	else

		return IOPRIO_CLASS_BE;

}



/*

 * For inheritance, return the highest of the two given priorities

 */