From c553f8e335c00a7cff3ab3f13e793b13d3f2207f Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Fri, 14 Jan 2011 08:41:03 +0100 Subject: 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: Shaohua Li Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'block') diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 7bfea53c1bb5..501ffdf0399c 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -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); } -- cgit v1.2.3