Re: [PATCH v3 2/5] blk-mq: Restart a single queue if tag sets are shared

[Jens Axboe <axboe@xxxxxxxxx>]

On 04/06/2017 12:10 PM, Bart Van Assche wrote:
> +		for (i = 0; i < queue->nr_hw_queues; i++) {
> +			j = (i + hctx->queue_num + 1) % queue->nr_hw_queues;
> +			h = queue->queue_hw_ctx[j];
> +			if (h->tags == tags && blk_mq_sched_restart_hctx(h))
> +				break;

I'm pretty sure that doing:

	j = i + hctx->queue_num + 1;;
	for (i = 0; i < queue->nr_hw_queues; i++, j++) {
		if (j == queue->nr_hw_queues)
			j = 0;
		h = queue->queue_hw_ctx[j];
		if (h->tags == tags && blk_mq_sched_restart_hctx(h))
			break;
	}

would be considerably more efficient than a modulo for each loop. And
let's rename 'h' to 'hctx', readability is much better that way.
Especially since you have both i and j as iterators.

-- 
Jens Axboe