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authorJens Axboe <axboe@suse.de>2005-08-24 14:57:54 +0200
committerLinus Torvalds <torvalds@g5.osdl.org>2005-08-24 10:22:44 -0700
commit9c2c38a122cc23d6a09b8004d60a33913683eedf (patch)
tree0596d9e3315a64d01f2a6f64d4f352f3cd0de08f
parent41290c14640bc9312bf63202d14ebef075b6171a (diff)
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[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.c31
1 files changed, 21 insertions, 10 deletions
diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
index 2435a7c99b2..cd056e7e64e 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) {
/*