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

From: Adrian Hunter
Date: Mon Sep 09 2019 - 08:45:03 EST

On 9/09/19 3:16 PM, Baolin Wang wrote:
> 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.

What about swq for software queue. Maybe Ulf can suggest something?