}
} else if (has_sched_dispatch) {
blk_mq_do_dispatch_sched(hctx);
- } else if (q->mq_ops->get_budget) {
- /*
- * If we need to get budget before queuing request, we
- * dequeue request one by one from sw queue for avoiding
- * to mess up I/O merge when dispatch runs out of resource.
- *
- * TODO: get more budgets, and dequeue more requests in
- * one time.
- */
+ } else if (hctx->dispatch_busy) {
+ /* dequeue request one by one from sw queue if queue is busy */
blk_mq_do_dispatch_ctx(hctx);
} else {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
return e->type->ops.mq.bio_merge(hctx, bio);
}
- if (hctx->flags & BLK_MQ_F_SHOULD_MERGE) {
+ if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
+ !list_empty_careful(&ctx->rq_list)) {
/* default per sw-queue merge */
spin_lock(&ctx->lock);
ret = blk_mq_attempt_merge(q, ctx, bio);
}
void blk_mq_sched_insert_request(struct request *rq, bool at_head,
- bool run_queue, bool async, bool can_block)
+ bool run_queue, bool async)
{
struct request_queue *q = rq->q;
struct elevator_queue *e = q->elevator;
if (e && e->type->ops.mq.insert_requests)
e->type->ops.mq.insert_requests(hctx, list, false);
- else
+ else {
+ /*
+ * try to issue requests directly if the hw queue isn't
+ * busy in case of 'none' scheduler, and this way may save
+ * us one extra enqueue & dequeue to sw queue.
+ */
+ if (!hctx->dispatch_busy && !e && !run_queue_async) {
+ blk_mq_try_issue_list_directly(hctx, list);
+ if (list_empty(list))
+ return;
+ }
blk_mq_insert_requests(hctx, ctx, list);
+ }
blk_mq_run_hw_queue(hctx, run_queue_async);
}