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Altera_Forum's avatar
Altera_Forum
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13 years ago

increasing performance of nios 2

Hallo,

Is there any possibility to increase the performance of nios II in C4 related to the debug configuration?

I know this from some µCs the there is a big increase by disabling the debug feature.

Is there any “switch” for nios II which results the same?

Thanks

sim

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    The JTAG debug doesn't affect the execution time of normal code.

    For best performance:

    - Make sure you compile everything (including the BSP/C library) with -O2 or -O3.

    - Don't use floating point.

    - Don't use printf.

    - Try to use as little of the C libarary as possible.

    - Fit all your code and data into tightly coupled memory.

    - Don't use Altera's alt_main() code unless you really need the stdio setup and teardown (forces malloc() and friends into your image).

    - Use the 'small data' segment (%gp relative addressing) for as much data as possible.

    - Write C very carefully to give the compiler the best chance of optimising the code.
  • Altera_Forum's avatar
    Altera_Forum
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    Hallo,

    thanks for your answer.

    Could you explain your first point in more detail?

    Where is it to finde and what is the meaning?
  • Altera_Forum's avatar
    Altera_Forum
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    I have also seen the option

    APP_CFLAGS_OPTIMIZATION := -Os

    in templates. But I could not find -Os in any document. What is that?

    Greets

    sim
  • Altera_Forum's avatar
    Altera_Forum
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    -Os is optimize for space. It will create a smaller binary, but maybe not the fastest one. If you are looking for performance it is better to use -O2 or -O3

  • Altera_Forum's avatar
    Altera_Forum
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    Ok, thanks.

    Now I removed the '-g' option in BSP editor. Then I build all again. But the code size did not decrease. How could that be?