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Commit c553f8e3 authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
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block cfq: compensate preempted queue even if it has no slice assigned 



If a queue is preempted before it gets slice assigned, the queue doesn't get
compensation, which looks unfair. For such queue, we compensate it for a whole
slice.

Signed-off-by: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent f8ae6e3e

block/cfq-iosched.c

+15 −4
Original line number Original line Diff line number Diff line
@@ -598,8 +598,8 @@ cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) 
	return cfq_target_latency * cfqg->weight / st->total_weight;

	return cfq_target_latency * cfqg->weight / st->total_weight;

}

}





static inline void

static inline unsigned

cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)

cfq_scaled_group_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)

{

{

	unsigned slice = cfq_prio_to_slice(cfqd, cfqq);

	unsigned slice = cfq_prio_to_slice(cfqd, cfqq);

	if (cfqd->cfq_latency) {

	if (cfqd->cfq_latency) {
@@ -625,6 +625,14 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 
				    low_slice);

				    low_slice);

		}

		}

	}

	}

	return slice;

}



static inline void

cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)

{

	unsigned slice = cfq_scaled_group_slice(cfqd, cfqq);



	cfqq->slice_start = jiffies;

	cfqq->slice_start = jiffies;

	cfqq->slice_end = jiffies + slice;

	cfqq->slice_end = jiffies + slice;

	cfqq->allocated_slice = slice;

	cfqq->allocated_slice = slice;
@@ -1661,7 +1669,10 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, 
	/*

	/*

	 * store what was left of this slice, if the queue idled/timed out

	 * store what was left of this slice, if the queue idled/timed out

	 */

	 */

	if (timed_out && !cfq_cfqq_slice_new(cfqq)) {

	if (timed_out) {

		if (cfq_cfqq_slice_new(cfqq))

			cfqq->slice_resid = cfq_scaled_group_slice(cfqd, cfqq);

		else

			cfqq->slice_resid = cfqq->slice_end - jiffies;

			cfqq->slice_resid = cfqq->slice_end - jiffies;

		cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);

		cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);

	}

	}