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

On Thu, Jul 13, 2017 at 10:14:31AM -0600, Jens Axboe wrote:

On 07/13/2017 10:10 AM, weiping zhang wrote:

quoted

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