On 5 October 2017 at 12:55, Bartlomiej Zolnierkiewicz
[off-list ref] wrote:

On Wednesday, October 04, 2017 11:48:27 AM Ulf Hansson wrote:

quoted

[...]

quoted

quoted

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).

I agree!

However my plan was to move forward with the CMDQ series, but I
realize that I may need to drop the Kconfig patch, in case CMDQ don't
make it for 4.15.

Kind regards
Uffe