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Any idea why the function in a multithreaded program is working at about 1/4 speed than when it works in a single thread?
I am benchmarking the net performance of the functions (it doesn't include any waits, locks, anything)?
Thanks
Soroin
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Hi Soroin
can we see your test code ?
If multiple threads work on resource that should be accessed by one thread at a time, there could be performance loss for the reason of concurrency control.
- Jon
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Hi Sorin,
could you provide a reproducer? Each IPP release is distributed with IPP PS (perf system) - therefore you can try 2 executable (with -B -r -fFIRMR switches) and compare results from corresponding CSV files:
ps_ipps_mrg_compl_mt.exe (mt==multithreaded) or
ps_ipps_mrg_compl_st.exe (st == singlethreaded)
or run ps_ipps_pcs.exe with multi-threaded dlls/shared objects and single-threaded.
I see good scalability for numIters >= 2K and tapsLen >= 32 (FIRMR has internal criterions on input parameters and mt-code works only for rather large filter orders and number of iterations (also depends on architecture)).
regards, Igor
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The ipp is run as single threaded IPP. Multithreading is achieved externally.
What is IPP PS (perf system)?
I work on Windows.
Thanks,
Sorin
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Sorin, can you check this article:
https://software.intel.com/en-us/articles/measure-intel-ipp-function-performance
thanks,
Chao
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