On Friday 11 February 2011, Lei Wen wrote:

quoted

Several orders of magnitude. It is very easy to get a card that can write
12 MB/s into a case where it writes no more than 30 KB/s, doing only
things that happen frequently with ext3.

Maybe we could get that case into mmc_test code, so that we could track
that in latter whether it already be fixed or not? Or in other word, to prove
the firmware in sd card is stupid or not. :)

 
There are many kinds of stupid, and a lot of cards are. I've actually had
excellent success with simply measuring from user space, which is
much easier than in mmc_test.

Unfortunately, you have to write to the card to do that, which may destroy
the data even if you write the same data that is already on it.

See
https://wiki.linaro.org/WorkingGroups/KernelConsolidation/Projects/FlashCardSurvey
for most of my results. I'm about to write up a better paper with all the
measurements, and will make my tools available soon.


	Arnd