[parsec-users] the OpenMP version blackscholes has No speedup when has more than 4 cores

kishore kumar kishoreguptaos at gmail.com
Mon Oct 14 21:58:23 EDT 2013


What do you mean by poor performance? Is it speedup? I guess that you run
blackscholes with native inputs. With large inputs, blackscholes main
thread does more work (serial execution -- reading input file, etc.,)
compared to the worker threads (parallel execution). Around 95% of the
entire execution time, you only see one thread, i.e., main thread. May be
you want to read "Thread Reinforcer: Dynamically Determining Number of
Threads" paper.

Thanks.

Best,
Kishore Kumar Pusukuri
http://www.cs.ucr.edu/~kishore


On Mon, Oct 14, 2013 at 6:34 PM, Eric Lu <eirc.lew at gmail.com> wrote:

> Hi,
>
> I run PARSEC2.1 on Intel E7520 machine, the os is centos6.3, the gcc-4.7
> compiler. The machine has 32 cores in total, and the results seems
> blackscholes has too poor performance.
> The data shows as follow:
> OpenMP
> proc blackscholes
> 1 0.998269
> 2 1.80499
> 4 1.763301
> 8 1.550916
> 16 1.542871
> 32 2.508076
>
>
>
> Best Regards!
>
>
> Eric
>
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> parsec-users at lists.cs.princeton.edu
> https://lists.cs.princeton.edu/mailman/listinfo/parsec-users
>
>
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