On Thu, Jan 20, 2011 at 12:30 PM, Simon Horman <horms@xxxxxxxxxxxx> wrote: > I ran my tests again with CONFIG_SH_DMAE (and CONFIG_DMA_ENGINE) > enabled and the results are substantially better. Although > the results are still below the theoretical speeds of the cards. > > Read Speed - SHDI > SD1.1: 9.9 MB/s > SD2.0: 17.2 MB/s > SDHC Class 2: 17.0 MB/s > SDHC Class 10: 17.2 MB/s > MMC4.0: 8.6 MB/s <-- Clocked down to 12Mhz due to driver limitations > > I also tested the Write Speed > SD1.1: 2.4 MB/s <-- Faster than expected > SD2.0: 2.8 MB/s <-- Faster than expected > SDHC Class 2: 2.5 MB/s <-- Faster than expected > SDHC Class 10: 3.8 MB/s <-- Slower than expected > MMC4.0: 2.1 MB/s <-- Clocked down to 12Mhz due to driver limitations > > For reference I obtained the following results on my laptop, > which according to dmesg has a SAMSUNG MMCRE28G VBM1 PQ. > > Read > SD1.1: 10.0 MB/s > SD2.0: 19.2 MB/s > SDHC Class 2: 19.4 MB/s > SDHC Class10: 17.9 MB/s <---- What!!!? > MMC4.0: 8.2 MB/s > > Write > SD1.1: 2.7 MB/s > SD2.0: 3.4 MB/s > SDHC Class 2: 3.1 MB/s > SDHC Class10: 3.8 MB/s <---- What!!!? > MMC4.0: 2.0 MB/s Interesting, thanks for running these tests. Two things cross my mind: 1) Can you try a different SDHC Class 10 card? I'd just simply buy a top-of-the-line SanDisk card myself and try that, but anything different from what you're having is probably useful as a contrast. 2) How about the MMC4.0 down-clocking. Is there anything we can do about that software-wise? Cheers, / magnus -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
