SDHC on dm6443

Please follow link for measurements, comparisons.

http://processors.wiki.ti.com/index.php/Managed_NAND#Performance_comparison

Do you have any specific issue? Are you working with any local FAE ?

Regards

Varada

Thanks for your answer.

But, my question is not to compare the NAND memories.

We developed a platform based on DM6443 with a SDHC extension. In fact, the uboot is on a NOR Flash, the kernel is on the second partition of the CF card and the filesystem is on the first partition of the CF card. We use always the same CF card.

And, some SDHC cards are observed poor performance.

So, my question is :

Why, with some models of  SDHC cards (same capacity and same speed class), the application has diffrent performance ?

Regards.

Please give more details.  Exactly which application is run and what is the speed difference in terms of R/W access times.

Regards

VArada

Hi,

I found the real problem. In our software, we open the file with the flag O_SYNC.
And, we write to the file on the SDHC card many buffers of 4KB.
I tested it with 2 SDHC cards and with many sizes of buffers.
The results are described below :

                    Kingston SDHC            SanDisk SDHC
                    4GB                        4GB
                    class 4                    class2
Buffers Size

    4 MB            2805 KB/s                2572 KB/s
    2 MB            2057 KB/s                2065 KB/s
    1 MB            1356 KB/s                2076 KB/s
    128 KB            232 KB/s                1375 KB/s   
    64 KB            117 KB/s                1475 KB/s   
    32 KB            76 KB/s                    871 KB/s   
    8 KB            15 KB/s                    351 KB/s   
    4 KB            14 KB/s                    211 KB/s   

I used our customize kernel 2.6.26 and a cross compilator of code sourcery (gcc 4.3.2 and glibc 2.8).

Can you explain the results?

Is it a bug of the kernel?
Or is it the hardware of the SDHC card ?
Or is it the hardware of your controller host sd/mmc (DM6443) ?

Regards

We are investigating with the driver teams here and help you narrow down the issue.

Regards

Varada

Were you investigated this problem?

And what is your answer?

Regards

Hi Jeje,

Are you still facing this problem? If you are using CFQ IO scheduler algorithm, please try to use a different one like "noop" or "deadline". This will solve the problem. If you are particular about using CFQ, please make the slice_idle parameter of CFQ to '0'. This will also help.

-Renjith

www.pathpartnertech.com