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

[Bart Van Assche <bart.vanassche@sandisk.com>]

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.