Urgent: DMA Timing Analysis Result

[Altera_Forum]

Hello. Currently I am using DMA to transfer data from SDRAM to SRAM. The size of the data is 10digit (from 0 to 9). the result from performance counter showing DMA is slower than using IOWR. why? is it because the data is too small? if i transfer 512kb of data, will the result be more significant? please help me! thank you!

[Altera_Forum]

Yes transferring a small amount of data will most probably be slower with a DMA, because of the time spent to configure the DMA core. The highest gains are with big transfers.

[Altera_Forum]

Thanks for the reply. If transferring 512KB of data, is it sufficient for testing?

[Altera_Forum]

It should be enough. But using a size closer to your final application might be more interesting for you.

[Altera_Forum]

I tried for 2MB of data but still IOWR and IORD is faster. why? The data is transfer inside the same SDRAM but different offset.

[Altera_Forum]

How faster? Are you sure you are measuring time correctly? 

You could use some signaltap probes on the SDRAM controller to see what is happening during the transfers.

[Altera_Forum]

Hi, it is done. Using DMA, it improves by 88.75%. Thanks ya! By the way, I have a question about performance counter report at http://www.alteraforum.com/forum/showthread.php?t=28665  

Please help me out. Thanks!