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

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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: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2008-05-07 09:51:23 +02:00
parent dbaf2c003e
commit 6d63c27557
2 changed files with 16 additions and 2 deletions
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4
block/cfq-iosched.c
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@ -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);

14
include/linux/ioprio.h
View file

@ -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
*/