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Altera_Forum
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14 years ago

Urgent: DMA Timing Analysis Result

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!

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    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's avatar
    Altera_Forum
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    14 years ago

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

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

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

  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    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's avatar
    Altera_Forum
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    14 years ago

    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.