Re: [PATCH 6/7] mq-deadline: add blk-mq adaptation of the deadline IO scheduler

[Bart Van Assche]

On 12/08/2016 09:13 PM, Jens Axboe wrote:

+static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
+{
+       struct deadline_data *dd;
+       struct elevator_queue *eq;
+
+       eq = elevator_alloc(q, e);
+       if (!eq)
+               return -ENOMEM;
+
+       dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
+       if (!dd) {
+               kobject_put(&eq->kobj);
+               return -ENOMEM;
+       }
+       eq->elevator_data = dd;
+
+       dd->tags = blk_mq_sched_alloc_requests(256, q->node);
+       if (!dd->tags) {
+               kfree(dd);
+               kobject_put(&eq->kobj);
+               return -ENOMEM;
+       }

Hello Jens,

Please add a comment that explains where the number 256 comes from.

Thanks,

Bart.