Estimate parallel efficiency using unicore processor

Question

We know that the parallel efficiency of a program running on a multicore system can be calculated as speedup/N where N is the number of cores. So in order to use this formula first we need to execute the code on a multicore system and need to know the speedup.

I would like to know if I don't have a multicore system,then is it possible to estimate the speedup of the given code on a multicore system just by executing it on an unicore processor?

I have access to performance counters ( Instruction per cycles , number of cache misses , Number of Instructions etc) and I only have binaries of the code.

[Note: I estimated the parallel_running_time (T_P) = serial_running_time/N but this estimation has unacceptable error]

Thanks

Answer 1

Read up on Amdahl's Law, especially the bit about parallelization.

For you to determine how much you can speed up your program, you have to know what parts of the program can benefit from parallelization and what parts must be executed sequentially. If you know that, and if you know how long the serial and the parallel parts take (individually) on a single processor, then you can estimate how fast the program will be on multiple processors.

From your description, it seems that you don't know which parts can make use of parallel processing and which parts have to be executed sequentially. So it won't be possible to estimate the parallel running time.