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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 12th April 2011 at http://forums.arm.com

    Hum.

    I think it's strange but it possible!
    That's clear that a NOP is replaced by a MOV r0,r0

    But on my beagleboard-XM it seem's that I can execute 2 NOP in the same cycle.
    May be you have another release of the cortex A8.

    That could be a answer.

    Documentation say's

    Assembling the NOP mnemonic as UAL will not change the functionality of the code, but will change:
    "¢ the instruction encoding selected
    "¢ the architecture variants on which the resulting binary will execute successfully, because the NOP instruction was introduced in ARMv6K and ARMv6T2.


    I'm not sure to really understand what it mean.

    I've no other explanation about the difference our results.

    Can you confirme me that with 10 NOP your program do not take 1 seconde ?
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  • 0
    Note: This was originally posted on 12th April 2011 at http://forums.arm.com

    Hum.

    I think it's strange but it possible!
    That's clear that a NOP is replaced by a MOV r0,r0

    But on my beagleboard-XM it seem's that I can execute 2 NOP in the same cycle.
    May be you have another release of the cortex A8.

    That could be a answer.

    Documentation say's

    Assembling the NOP mnemonic as UAL will not change the functionality of the code, but will change:
    "¢ the instruction encoding selected
    "¢ the architecture variants on which the resulting binary will execute successfully, because the NOP instruction was introduced in ARMv6K and ARMv6T2.


    I'm not sure to really understand what it mean.

    I've no other explanation about the difference our results.

    Can you confirme me that with 10 NOP your program do not take 1 seconde ?
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