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| author | Shaohua Li <shaohua.li@intel.com> | 2009-10-27 08:46:23 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-10-27 08:46:23 +0100 |
| commit | 1a1238a7dd48e48b3bba8f426a1d61c22c80d6d1 (patch) | |
| tree | 08a39610689b5da8e8d61701864b8eb257acd6d7 /block | |
| parent | e6c5bc737ab71e4af6025ef7d150f5a26ae5f146 (diff) | |
| download | lwn-1a1238a7dd48e48b3bba8f426a1d61c22c80d6d1.tar.gz lwn-1a1238a7dd48e48b3bba8f426a1d61c22c80d6d1.zip | |
cfq-iosched: improve hw_tag detection
If active queue hasn't enough requests and idle window opens, cfq will not
dispatch sufficient requests to hardware. In such situation, current code
will zero hw_tag. But this is because cfq doesn't dispatch enough requests
instead of hardware queue doesn't work. Don't zero hw_tag in such case.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/cfq-iosched.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 47d6aaca0c51..418da9a49bb0 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2257,6 +2257,8 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq) */ static void cfq_update_hw_tag(struct cfq_data *cfqd) { + struct cfq_queue *cfqq = cfqd->active_queue; + if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak) cfqd->rq_in_driver_peak = rq_in_driver(cfqd); @@ -2264,6 +2266,16 @@ static void cfq_update_hw_tag(struct cfq_data *cfqd) rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN) return; + /* + * If active queue hasn't enough requests and can idle, cfq might not + * dispatch sufficient requests to hardware. Don't zero hw_tag in this + * case + */ + 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) + return; + if (cfqd->hw_tag_samples++ < 50) return; |