On Mon, Feb 13, 2012 at 1:16 PM, Jeff Chua [off-list ref] wrote:

On Mon, Feb 13, 2012 at 12:41 PM, Jeff Chua [off-list ref] wrote:

quoted

I ran tests for frequency that works dd out 1G of data from 8MHz to
16MHz, and it seems frequency less than 8.4MHz can only transfer at
rate of 14.3MB/s and above 8.4MHz, speed goes up to 18.3 MB/s. Above
17MHz, errors encounters.

hz1  8000000  73.5029 s  14.3 MB/s
hz2  8000000  73.4740 s  14.3 MB/s
hz3  8000000  73.3982 s  14.3 MB/s
hz1  8200000  71.9677 s  14.6 MB/s
hz2  8200000  73.4936 s  14.3 MB/s
hz3  8200000  73.3462 s  14.3 MB/s
hz1  8400000  56.6296 s  18.5 MB/s
hz2  8400000  56.7616 s  18.5 MB/s
hz3  8400000  56.7926 s  18.5 MB/s
hz1  8600000  56.6622 s  18.5 MB/s
hz2  8600000  56.7201 s  18.5 MB/s
hz3  8600000  56.6476 s  18.5 MB/s
hz1  8800000  56.8846 s  18.4 MB/s
hz2  8800000  56.8226 s  18.5 MB/s
hz3  8800000  56.7070 s  18.5 MB/s

I've turned on write, and there's no error writing. But speed is
slower than accessing it via USB2 SD card reader. Same SD.

Via SD PCI
18.779 sec  4.04 %cpu

Via USB2.0 Card Reader
12.205 sec  2.04 %cpu

Via USB3.0 Card Reader
11.427 sec  2.01 %cpu


Shouldn't PCI SD be faster? Same SD used for all tests.

THanks,
Jeff


Thanks,
Jeff