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block cfq: compensate preempted queue even if it has no slice assigned

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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: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Shaohua Li 2011-01-14 08:41:03 +01:00 committed by Jens Axboe
parent f8ae6e3eb8
commit c553f8e335
1 changed files with 15 additions and 4 deletions
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19
block/cfq-iosched.c
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@ -598,8 +598,8 @@ cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
return cfq_target_latency * cfqg->weight / st->total_weight;
}
static inline void
cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
static inline unsigned
cfq_scaled_group_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
if (cfqd->cfq_latency) {
@ -625,6 +625,14 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
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_end = jiffies + slice;
cfqq->allocated_slice = slice;
@ -1661,8 +1669,11 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
/*
* store what was left of this slice, if the queue idled/timed out
*/
if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
cfqq->slice_resid = cfqq->slice_end - jiffies;
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;
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
}