Re: [PATCH RFC 09/22] block, cfq: replace CFQ with the BFQ-v0 I/O scheduler

From: Christoph Hellwig
Date: Fri Mar 11 2016 - 06:17:28 EST

On Sat, Mar 05, 2016 at 07:18:30PM +0700, Linus Walleij wrote:
> Depends on what time horizon and target I'd say. Paolo was in contact with
> the MMC/SD subsystem maintainer Ulf Hansson. (e)MMC/SD are both
> synchronous command-response-based protocols, and as of today
> single-channel. So everone's smartphone and tablet etc are today
> single-channel. I don't know if there is even a protocol change coming
> to augment this, the only duct-tapeish solution I've heard about is
> command queueing which is basically a kind of pipelining of requests.

We use blkj-mq for single queue devices as well, in fact most consumers
are single queue. MMC is a prime candidate that hould move over soon.