Re: [PATCH V9 13/15] mmc: block: Add CQE and blk-mq support

From: Bartlomiej Zolnierkiewicz
Date: Thu Oct 05 2017 - 06:56:06 EST

On Wednesday, October 04, 2017 11:48:27 AM Ulf Hansson wrote:
> [...]
> >> MQ code that doesn't perform and therefore we cannot switch seamlessly
> >> to MQ.
> >
> > I think that switching seamlessly to blk-mq in short/medium-term
> > is not possible (SCSI tried and failed to do so). The changes to
> > the old path are very complex and besides affecting performance
> > they also affect error recovery handling (which needs to be tested
> > properly before the switch).
> Agreed, and that's why I have queued up the new Kconfig option for
> enabling the blkmq path from MMC.

This seems premature - the new Kconfig option change for "mmc-mq" should
belong to the patch adding "mmc-mq" support (otherwise it may just confuse
users who enable it).

Best regards,
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics