On 4/11/23 05:38, Christoph Hellwig wrote:
On Fri, Apr 07, 2023 at 04:58:13PM -0700, Bart Van Assche wrote:
@@ -2065,9 +2057,14 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
if (nr_budgets)
blk_mq_release_budgets(q, list);
- spin_lock(&hctx->lock);
- list_splice_tail_init(list, &hctx->dispatch);
- spin_unlock(&hctx->lock);
+ if (!q->elevator) {
+ spin_lock(&hctx->lock);
+ list_splice_tail_init(list, &hctx->dispatch);
+ spin_unlock(&hctx->lock);
+ } else {
+ q->elevator->type->ops.insert_requests(hctx, list,
+ /*at_head=*/true);
+ }
But I have no idea how this is related in any way.
Hi Christoph,
The I/O scheduler can only control the order in which requests are
dispatched if:
- blk_mq_run_hw_queue() moves requests from the requeue list to the I/O
scheduler before it asks the I/O scheduler to dispatch a request.
- No requests end up on any other queue than the I/O scheduler queue or
the requeue list.
The scope of this patch is to send requeued requests back to the I/O
scheduler. Hence the above change.
Thanks,
Bart.
