Hi Ulf,
On 2017/2/17 20:09, Ulf Hansson wrote:
> [...]
>
>>
>> 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?
>
I'm glad to.
But my available platforms all stay in Linux v4.4/v4.1.
I can help when my platforms can upgrade.
>>
>>>
>>> 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.
>
Got it. Thanks a lot for your detailed explanation.
If we focus on the low latency, we shall get a cleaner result
of IOPS in tests.
IOPS is a more common performance index in eMMC/SD.
Thank you.
Best regards,
Hu Ziji
> Kind regards
> Uffe
>
