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cfq-iosched: use the default seek distance when there aren't enough seek samples

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If the cfq io context doesn't have enough samples yet to provide a mean
seek distance, then use the default threshold we have for seeky IO instead
of defaulting to 0.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jeff Moyer 2009-04-21 07:31:56 +02:00 committed by Jens Axboe
parent 4d00aa47e2
commit 04dc6e71a2
1 changed files with 6 additions and 5 deletions
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11
block/cfq-iosched.c
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@ -947,14 +947,18 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
return cfqd->last_position - rq->sector; return cfqd->last_position - rq->sector;
} }
#define CIC_SEEK_THR 8 * 1024
#define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq) static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
{ {
struct cfq_io_context *cic = cfqd->active_cic; struct cfq_io_context *cic = cfqd->active_cic;
sector_t sdist = cic->seek_mean;
if (!sample_valid(cic->seek_samples)) if (!sample_valid(cic->seek_samples))
return 0; sdist = CIC_SEEK_THR;
return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean; return cfq_dist_from_last(cfqd, rq) <= sdist;
} }
static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
@ -1039,9 +1043,6 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
return cfqq; return cfqq;
} }
#define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024))
static void cfq_arm_slice_timer(struct cfq_data *cfqd) static void cfq_arm_slice_timer(struct cfq_data *cfqd)
{ {
struct cfq_queue *cfqq = cfqd->active_queue; struct cfq_queue *cfqq = cfqd->active_queue;