cfq-iosched: don't regard requests with long distance as close
seek_mean could be very big sometimes, using it as close criteria is meaningless as this doen't improve any performance. So if it's big, let's fallback to default value. Reviewed-by: Corrado Zoccolo <czoccolo@gmail.com> Signed-off-by: Shaohua Li<shaohua.li@intel.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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@ -1667,13 +1667,17 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
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#define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
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static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
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struct request *rq)
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struct request *rq, bool for_preempt)
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{
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sector_t sdist = cfqq->seek_mean;
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if (!sample_valid(cfqq->seek_samples))
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sdist = CFQQ_SEEK_THR;
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/* if seek_mean is big, using it as close criteria is meaningless */
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if (sdist > CFQQ_SEEK_THR && !for_preempt)
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sdist = CFQQ_SEEK_THR;
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return cfq_dist_from_last(cfqd, rq) <= sdist;
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}
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@ -1701,7 +1705,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
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* will contain the closest sector.
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*/
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__cfqq = rb_entry(parent, struct cfq_queue, p_node);
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if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
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if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq, false))
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return __cfqq;
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if (blk_rq_pos(__cfqq->next_rq) < sector)
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@ -1712,7 +1716,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
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return NULL;
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__cfqq = rb_entry(node, struct cfq_queue, p_node);
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if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
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if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq, false))
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return __cfqq;
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return NULL;
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@ -3112,7 +3116,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
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* if this request is as-good as one we would expect from the
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* current cfqq, let it preempt
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*/
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if (cfq_rq_close(cfqd, cfqq, rq))
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if (cfq_rq_close(cfqd, cfqq, rq, true))
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return true;
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return false;
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