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Performace evaluation on C674x

Jean Belleau
Prodigy 90 points

Hi,

We are planning to use the C674x processors. Is it possible to figure out the impact on performance of using a 16 bits or 32 bits wide data bus on external SDRAM memory. For sure the transfer speed is two times faster from external memory but the CPU is running from cache most of the time. Then, the type of software running will also have an impact. Is there any kind of benchmark about this?

Regards

Jean

 

 

  • 0
    TI__Expert 5215 points

    Jean,

    A colleague of mine did some testing on throughput to an SDRAM over the EMIFB @ 32/16bit on a C6747. Passing 32-bit data you would expect the 16-bit bus to have roughly half the throughput...but that wasn't the case. It may just be a matter of how quickly the CPU can access the EMIF port versus how quickly the EDMA can do the same. He wrote 5000 32-bit vales via pointer in a for loop, with no other system traffic:

    • 16-bit data bus took 2820 cycles
    • 32-bit data bus took 2072 cycles

    He found a noticiable throughput improvement when using EDMA3 over a direct pointer. (Although, still not near the 2x amount).

    Hope that helps.

  • 0
    TI__Guru*** 125430 points

    Jean Belleau said:
    Then, the type of software running will also have an impact.

    Exactly -- the performance will be specific to your code.  You would need to perform your own benchmark of your own code to really get an understanding.