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Parallella Community • View topic - Timer calculation

Timer calculation

Any technical questions about the Epiphany chip and Parallella HW Platform.

Moderator: aolofsson

Timer calculation

Postby vanchiramani » Sun Nov 27, 2016 7:05 am

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Re: Timer calculation

Postby jar » Mon Nov 28, 2016 1:42 pm

A lot more is happening to launch a kernel than you may think. The host is moving memory around. At the very least, 16 copies of your program have to be written (once to each core). The COPRTHR-2 loader is much faster than alternatives since it copies one program from the host to an Epiphany core, then that Epiphany core replicates its contents to the next core, and so on.

Read the paper "Advances in Run-Time Performance and Interoperability for the Adapteva Epiphany Coprocessor" to understand more how kernels are launched.

Host and core timings will never be consistent until you significantly increase your workload.
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Re: Timer calculation

Postby vanchiramani » Mon Nov 28, 2016 2:39 pm

I totally agree that there may be inconsistencies in the timing calculation between host and device.

The main concern that I have is that irrespective of increasing the loop bound, the epiphany timer value does not increase. However, the timing calculated using ARM increases with loop bound size.
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Re: Timer calculation

Postby jar » Mon Nov 28, 2016 7:47 pm

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