On 07/27/2017 07:26 AM, Christoph Hellwig wrote: > On Wed, Jul 26, 2017 at 02:40:50PM -0600, Jens Axboe wrote: >> On 07/26/2017 02:19 PM, Christoph Hellwig wrote: >>> This avoids having to deal with the nr_hw_queues = 1 case in the various >>> queue mapping helpers by special casing it in the blk-mq core. >> >> Why special case it at all? If ->map_queues() is properly written, >> the single queue case should just fall out naturally. I don't see >> why 1 should be any different than 2, 4, or N. > > Because 1 means everything maps to queue 0 and there is no point > in asking any lower layers for a specific mapping. We could instead > special case it in pci, virtio and the upcoming rdma handler, or > we could just do it once in the core and get same result with less > overhead. Sure, my point is that the nr_queues == 1 case should just naturally fall out of the mapping function, it's no more special than the other ones. -- Jens Axboe
