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Altera_Forum's avatar
Altera_Forum
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20 years ago

memory performance

hi,

I'm using NIOSII at around 50Mc with SRAM at the moment, but for some new project, I want to investigate an upgrade path with higher performance.

The SRAM I use at the moment uses no wait states and an unregistered tri-state bridge.

If I want to go to higher clock speeds, I have several options :

- using wait states with the current SRAM

- using a registered tri-state bridge with current SRAM

- using other memory technology (Synchronuous SRAM, SDRAM, ...)

Any idea what the performance benifits or disadvantages are according to processing power? In other words, what is better, going to Sync SRAM or SDRAM or introduce wait states? I want to evaluate going from 50 Mc to somewhare around 80Mc.

Stefaan

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    Hi,

    I know it's not related to the question you posed, but... what about an alternative upgrade path that has more CPUs maintaining the same clock speed?

    Bye

    Paolo
  • Altera_Forum's avatar
    Altera_Forum
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    20 years ago

    Ok, but then I need two tri-state bridges and two sets of RAMS connected seperatly to the FPGA. Otherwise the RAM will be the bottleneck again.

    My application is not very 'cacheble'.

    Stefaan
  • Altera_Forum's avatar
    Altera_Forum
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    20 years ago

    What is your goal, just to increase processor speed, or overall memory bandwidth. The SRAM or SSRAM devices are obviously faster access, but they offer less density per cost, so you have to factor in that. I would say if you are looking to increase your clock speed of the processor, and can tradeoff a little in initial access time, move to the synchronous DRAM interfaces such as DDR or DDR2. There performance is undoubtedly less than SRAM, but their cost per density is much better. I can use DDR and a Nios II processor at about 85M in a Cyclone II for reference.

    I didn&#39;t understand your Q too clearly, so my apologies if I just went off on a tangent http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    sorry for the late reply,

    Indeed, I want to boost processor performance, looking to a possible upgrade path for our existing system.

    We use a preemptive operating system, with a rather high interrupt load and task switch load. I don&#39;t know yet how to rate the performance of the global working of the system. I can measure interrupt latency and task swith times, but how does the application behaves with different memory types and caches, I don&#39;t know yet.

    Stefaan