[...]

        I would like to suggest that you should try the multiple thread
        test mode of iozone, since you are testing *Multi* Queue.

Yes. That seems reasonable.

However, the most important part here is the comparison between the
different code bases.

        Besides, it seems that your eMMC transfer speed is quite low.
        It is normal that read speed can reach more than 100MB/s in HS400.
        Could you try a higher speed mode? The test result might be
        limited by the bus clock frequency.

Perhaps if Linus can share a branch of the code integrated for the
different tests, we all can help out running them on those HW we have
at hand. Would you be willing to help out here?

quoted

As you can see there are no huge performance regressions with these
kinds of "raw" throughput tests.

These iozone figures are unintuitive unless your head can
plot logarithmic, look at the charts here for a more visual presentation
of the iozone results:
https://docs.google.com/spreadsheets/d/1rm72TiGlTnzDeGLR__aqvjcJ2UkA-Ro3-XyKA8r1M-c

Compare this to the performance change we got when first introducing
the asynchronous requests:
https://wiki.linaro.org/WorkingGroups/KernelArchived/Specs/StoragePerfMMC-async-req

The patches need some issues fixed from the build server
complaints and some robustness hammering, but after that I
think they will be ripe for merging for v4.12.

        Actually I have been following your thread for some time.
        But currently I'm a little confused.
        May I know the purpose of your patch?

I want MMC to move to the new BLKMQ interface and I want that because
of several reasons, see below.

1. It's new blk interface, all new development happens here. We should
use it to benefit from that.
2. The BLKMQ interface allow the MMC block device driver to be
significantly cleaner implemented - and I need that to be able to
maintain the code.
3. We want to make use of Paolo's BFQ-MK I/O scheduler, which
addresses provides guaranteed low latency. For example being able to
play a video clip, while doing a disc backup without getting frame
drops.

Kind regards
Uffe