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authorAaron Carroll <aaronc@gelato.unsw.edu.au>2008-08-14 18:17:13 +1000
committerJens Axboe <jens.axboe@oracle.com>2008-10-09 08:56:02 +0200
commit63de428b139d3d31d86ebe25ae97b33f6540fb7e (patch)
treedef85c8e9990293effe71baf3b0dce648eab516c
parent766ca4428d1239a970926856c447310c9c191af2 (diff)
downloadop-kernel-dev-63de428b139d3d31d86ebe25ae97b33f6540fb7e.zip
op-kernel-dev-63de428b139d3d31d86ebe25ae97b33f6540fb7e.tar.gz
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>
-rw-r--r--block/deadline-iosched.c14
1 files changed, 3 insertions, 11 deletions
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 @@ static int deadline_dispatch_requests(struct request_queue *q, int force)
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
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