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Altera_Forum's avatar
Altera_Forum
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11 years ago

__constant cache size

Hi folks,

What is the practical limit of the __constant cache size?

I have a constant 16MiB buffer that's needed. If I use the option "--const-cache-bytes 16777216", is it going to fill all in cache? What type of resource does the cache take?

Thanks,

Smith

2 Replies

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

    The area report should give you a good idea of how much of the FPGA RAMs will get used up. Really this depends on your FPGA device. An SV-A7 has 50 Mb (b as in bits), some are already used by the board design, some by your kernel pipeline. If you really need something that big, I'd say start with half your device's bits.

    Note, the constant cache suffers from very steep miss penalties. You should really only use it for data that rarely (or never) gets evicted.