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    Critical Path in a design

    Hi everyone
    After the compilation, given that we are at the top level, using the report_timing we obtain a certain path with a certain time X. After changing the current design(going more inside) and using the report_timing command again, we obtain a path with a time that is HIGHER than X. Why? Shouldn't the report_timing command display the same path when we are in the top level design?

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  2. #2
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    Re: Critical Path in a design

    Quote Originally Posted by onta00 View Post
    Hi everyone
    After the compilation, given that we are at the top level, using the report_timing we obtain a certain path with a certain time X. After changing the current design(going more inside) and using the report_timing command again, we obtain a path with a time that is HIGHER than X. Why? Shouldn't the report_timing command display the same path when we are in the top level design?
    are you sure you are not confusing the path timing with the slack? slack is supposed to be higher.
    Really, I am not Sam.



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  3. #3
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    Re: Critical Path in a design

    Quote Originally Posted by ThisIsNotSam View Post
    are you sure you are not confusing the path timing with the slack? slack is supposed to be higher.
    The command report_timing reports timing paths. I've used the same command in the top level entity and in the inner entity



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  4. #4
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    Re: Critical Path in a design

    Quote Originally Posted by onta00 View Post
    The command report_timing reports timing paths. I've used the same command in the top level entity and in the inner entity
    It reports slacks. Make sure you are not reading it wrong. Care to post the paths here?
    Really, I am not Sam.


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    Re: Critical Path in a design

    At the top level the worst path will be any path in the top level. At "current_instance <hier>", the worst path will be only the worst path within that particular <hier>. Check that you have the exact same timing path reported in both cases.


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