Re: [PATCH 2/4] mmc: Add virtual command queue support

From: Baolin Wang
Date: Mon Sep 09 2019 - 08:17:00 EST


Hi Adrian,

On Mon, 9 Sep 2019 at 20:02, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> On 6/09/19 6:52 AM, Baolin Wang wrote:
> > Now the MMC read/write stack will always wait for previous request is
> > completed by mmc_blk_rw_wait(), before sending a new request to hardware,
> > or queue a work to complete request, that will bring context switching
> > overhead, especially for high I/O per second rates, to affect the IO
> > performance.
> >
> > Thus this patch introduces virtual command queue interface, which is
> > similar with the hardware command queue engine's idea, that can remove
> > the context switching.
>
> CQHCI is a hardware interface for eMMC's that support command queuing. What
> you are doing is a software issue queue, unrelated to CQHCI. I think you

Yes.

> should avoid all reference to CQHCI i.e. call it something else.

Since its process is similar with CQHCI and re-use the CQHCI's
interfaces, I called it virtual command queue. I am not sure what else
name is better, any thoughts? VCQHCI? Thanks.

--
Baolin Wang
Best Regards