diff options
| author | Jens Axboe <axboe@suse.de> | 2005-08-24 14:57:54 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-08-24 10:22:44 -0700 |
| commit | 9c2c38a122cc23d6a09b8004d60a33913683eedf (patch) | |
| tree | 0596d9e3315a64d01f2a6f64d4f352f3cd0de08f | |
| parent | 41290c14640bc9312bf63202d14ebef075b6171a (diff) | |
| download | linux-9c2c38a122cc23d6a09b8004d60a33913683eedf.tar.bz2 | |
[PATCH] cfq-iosched.c: minor fixes
One critical fix and two minor fixes for 2.6.13-rc7:
- Max depth must currently be 2 to allow barriers to function on SCSI
- Prefer sync request over async in choosing the next request
- Never allow async request to preempt or disturb the "anticipation" for
a single cfq process context. This is as-designed, the code right now
is buggy in that area.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | drivers/block/cfq-iosched.c | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c index 2435a7c99b2b..cd056e7e64ec 100644 --- a/drivers/block/cfq-iosched.c +++ b/drivers/block/cfq-iosched.c @@ -47,7 +47,7 @@ static int cfq_slice_idle = HZ / 100; /* * disable queueing at the driver/hardware level */ -static int cfq_max_depth = 1; +static int cfq_max_depth = 2; /* * for the hash of cfqq inside the cfqd @@ -385,9 +385,15 @@ cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) return crq2; if (crq2 == NULL) return crq1; - if (cfq_crq_requeued(crq1)) + + if (cfq_crq_requeued(crq1) && !cfq_crq_requeued(crq2)) return crq1; - if (cfq_crq_requeued(crq2)) + else if (cfq_crq_requeued(crq2) && !cfq_crq_requeued(crq1)) + return crq2; + + if (cfq_crq_is_sync(crq1) && !cfq_crq_is_sync(crq2)) + return crq1; + else if (cfq_crq_is_sync(crq2) && !cfq_crq_is_sync(crq1)) return crq2; s1 = crq1->request->sector; @@ -1769,18 +1775,23 @@ static void cfq_crq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, struct cfq_rq *crq) { - const int sync = cfq_crq_is_sync(crq); + struct cfq_io_context *cic; cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); - if (sync) { - struct cfq_io_context *cic = crq->io_context; + /* + * we never wait for an async request and we don't allow preemption + * of an async request. so just return early + */ + if (!cfq_crq_is_sync(crq)) + return; - cfq_update_io_thinktime(cfqd, cic); - cfq_update_idle_window(cfqd, cfqq, cic); + cic = crq->io_context; - cic->last_queue = jiffies; - } + cfq_update_io_thinktime(cfqd, cic); + cfq_update_idle_window(cfqd, cfqq, cic); + + cic->last_queue = jiffies; if (cfqq == cfqd->active_queue) { /* |