deadline-iosched: allow non-sequential batching
Deadline currently only batches sector-contiguous requests, so except
for a few circumstances (e.g. requests in a single direction), it is
essentially first come first served. This is bad for throughput, so
change it to CSCAN, which means requests in a batch do not need to be
sequential and are issued in increasing sector order.
Signed-off-by: Aaron Carroll <aaronc@gelato.unsw.edu.au>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 342448c..07b80e4 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -258,17 +258,9 @@
else
rq = dd->next_rq[READ];
- if (rq) {
- /* we have a "next request" */
-
- if (dd->last_sector != rq->sector)
- /* end the batch on a non sequential request */
- dd->batching += dd->fifo_batch;
-
- if (dd->batching < dd->fifo_batch)
- /* we are still entitled to batch */
- goto dispatch_request;
- }
+ if (rq && dd->batching < dd->fifo_batch)
+ /* we have a next request are still entitled to batch */
+ goto dispatch_request;
/*
* at this point we are not running a batch. select the appropriate