Feedback on benchmarking results of SDHCI and MMCCAM driver

[Russell Haley]

On Mon, May 14, 2018 at 2:51 PM, Udit agarwal <dev.madaari at gmail.com> wrote:

> On Tue, May 15, 2018 at 3:11 AM, Peter Jeremy <peter at rulingia.com> wrote:
>
> > On 2018-May-15 02:48:43 +0530, Udit agarwal <dev.madaari at gmail.com>
> wrote:
> > >I have conducted several sd card benchmarking tests on FreeBSD 11.1,
> with
> > >both SDHCI and the newly incorporated MMCCAM driver to compare their
> > >performance under different conditions.
> >
> > Some questions:
> > 1) How reproduceable are the results?  Have you performed the test
> > multiple times
> > to check for variance?
>
The images that Udit is using for his tests can be made available for
verification if that's desirable (we have a webserver available). His blogs
are very good as well.


>
> Yes, i have carried these tests multiple time and the results are pretty
> consistent upto 0.1MBPS.
>
> > 2) How did you prepare the SD card prior to each write test?  Flash write
> > tests
> > are extremely sensitive to hidden move/rewrite and erase cycles performed
> > by the
> > flash translation layer.
> >
> Before each test, I freshly recreated the filesystem to remove any trace of
> the previous tests. Moreover, I have mounted/unmounted the device  to purge
> any data in the cache.
>
> > 3) Have you tried different SD cards from different manufacturers to see
> > if the
> > drivers happen to interact well or badly with the specific flash
> > implementation.
> >
> No, currently i havn't experimented with different sd cards. True, it would
> be interesting to figure out the interaction of the driver with different
> flash implementations. I'll perform these tests ASAP.
>

I'll just point out that Udits SGOC project has nothing to do with the
flash implementation of the cards. Udit, I would hesitate to go down the
road of multiple card tests unless you have a great deal of spare time.
There are far more pertinent questions that can be asked about the variance
between SDHCI and SDIO implementations. There is still the little detail of
porting to RTEMS too. :)


> Regards,
> Udit
>
> >
> > --
> > Peter Jeremy
> >
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