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Cortex A8 Instruction Cycle Timing

barney vardanyan
Note: This was originally posted on 17th March 2011 at http://forums.arm.com

Hi) sorry for bad English

I need to count latency for two instruction, and all I have is the arm cortex A 8 documantation(charter 16) !
but I have no idea how can do this work using that documantation(
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    Note: This was originally posted on 11th April 2011 at http://forums.arm.com

    I have made tests, and get very strange results.

    the test is folowing

    I have some cycle and nop intsructions in it.

    first I have only one nop in cycle, it's takes  0.570 s on my board
    then I add second nop instruction, and it's also takes 0.57 s. and it's true, becaues they executed  in thy same cycle(pipeline 0 and pipeline 1)
    then I continue to add nop instructions.
    So when I got to 5-6 nop pair, I realize that they can't execute parraler
    and after  every nop instruction that I add increase the time of execution

    So why after 5 nop, they don't executed parraler, IS there any idea?

    here is the test file)
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  • 0
    Note: This was originally posted on 11th April 2011 at http://forums.arm.com

    I have made tests, and get very strange results.

    the test is folowing

    I have some cycle and nop intsructions in it.

    first I have only one nop in cycle, it's takes  0.570 s on my board
    then I add second nop instruction, and it's also takes 0.57 s. and it's true, becaues they executed  in thy same cycle(pipeline 0 and pipeline 1)
    then I continue to add nop instructions.
    So when I got to 5-6 nop pair, I realize that they can't execute parraler
    and after  every nop instruction that I add increase the time of execution

    So why after 5 nop, they don't executed parraler, IS there any idea?

    here is the test file)
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