Re: [PATCH] blk-mq: only alloc hctx point as many as nr_hw_queues

weiping zhang
2017-07-13T16:30:37Z

On Thu, Jul 13, 2017 at 10:14:31AM -0600, Jens Axboe wrote:
> On 07/13/2017 10:10 AM, weiping zhang wrote:
> > one hw queue only has one hctx, reduce it's number same as nr_hw_queues.
>
> What happens if a device registers with eg 4 hw queues, then later
> calls blk_mq_update_nr_hw_queues()?
>

your means, 10 cpu, and device has 10 hw queues, but only register 4,
and then update it to 10, no place store new hctx. Am i understanding
right ? if yes, could you tell me why driver do that ? thanks.

--
weiping