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cfq-iosched: requests "in flight" vs "in driver" clarification 

Counters for requests "in flight" and "in driver" are used asymmetrically
in cfq_may_dispatch, and have slightly different meaning.
We split the rq_in_flight counter (was sync_flight) to count both sync
and async requests, in order to use this one, which is more accurate in
some corner cases.
The rq_in_driver counter is coalesced, since individual sync/async counts
are not used any more.

Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Corrado Zoccolo 2010-02-28 19:45:05 +01:00 committed by Jens Axboe
parent 87c3a922a7
commit 53c583d226
1 changed files with 18 additions and 26 deletions
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44
block/cfq-iosched.c
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@ -222,8 +222,8 @@ struct cfq_data {
unsigned int busy_queues;
int rq_in_driver[2];
int sync_flight;
int rq_in_driver;
int rq_in_flight[2];
/*
* queue-depth detection
@ -416,11 +416,6 @@ static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
struct io_context *);
static inline int rq_in_driver(struct cfq_data *cfqd)
{
return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
}
static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
bool is_sync)
{
@ -1414,9 +1409,9 @@ static void cfq_activate_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
cfqd->rq_in_driver[rq_is_sync(rq)]++;
cfqd->rq_in_driver++;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
rq_in_driver(cfqd));
cfqd->rq_in_driver);
cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
}
@ -1424,12 +1419,11 @@ static void cfq_activate_request(struct request_queue *q, struct request *rq)
static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
const int sync = rq_is_sync(rq);
WARN_ON(!cfqd->rq_in_driver[sync]);
cfqd->rq_in_driver[sync]--;
WARN_ON(!cfqd->rq_in_driver);
cfqd->rq_in_driver--;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
rq_in_driver(cfqd));
cfqd->rq_in_driver);
}
static void cfq_remove_request(struct request *rq)
@ -1863,8 +1857,7 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
cfqq->dispatched++;
elv_dispatch_sort(q, rq);
if (cfq_cfqq_sync(cfqq))
cfqd->sync_flight++;
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
cfqq->nr_sectors += blk_rq_sectors(rq);
}
@ -2211,13 +2204,13 @@ static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
/*
* Drain async requests before we start sync IO
*/
if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
return false;
/*
* If this is an async queue and we have sync IO in flight, let it wait
*/
if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
return false;
max_dispatch = cfqd->cfq_quantum;
@ -3189,14 +3182,14 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
if (rq_in_driver(cfqd) > cfqd->hw_tag_est_depth)
cfqd->hw_tag_est_depth = rq_in_driver(cfqd);
if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
if (cfqd->hw_tag == 1)
return;
if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
return;
/*
@ -3206,7 +3199,7 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd)
*/
if (cfqq && cfq_cfqq_idle_window(cfqq) &&
cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN)
CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
return;
if (cfqd->hw_tag_samples++ < 50)
@ -3259,13 +3252,12 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
cfq_update_hw_tag(cfqd);
WARN_ON(!cfqd->rq_in_driver[sync]);
WARN_ON(!cfqd->rq_in_driver);
WARN_ON(!cfqq->dispatched);
cfqd->rq_in_driver[sync]--;
cfqd->rq_in_driver--;
cfqq->dispatched--;
if (cfq_cfqq_sync(cfqq))
cfqd->sync_flight--;
cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
if (sync) {
RQ_CIC(rq)->last_end_request = now;
@ -3319,7 +3311,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
}
}
if (!rq_in_driver(cfqd))
if (!cfqd->rq_in_driver)
cfq_schedule_dispatch(cfqd);
}