4 threads activated but juste one thread doesn't work

4 threads activated but juste one thread doesn't work

Hello everybody,

I'm using intel amplifer xe 2011 to analyse my program's performance on multicore system.

I set for example 4 workers to run my program. Note that i'm using the cilk plus langage.

The hotspot show me that 4 threads are activated but there is one thread that doesn't work (there is no cpu time).

I have attached a picture that show an example.

have you an idea for this problem ?

Thank you in advance.

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I think that result is correct - I know that you set 4 workers, already.

I suspect that your program only ran 0.16s, it means that Cilk+ only spent 3 threads to complete your work quickly.
My opinion is to add workload in your progran then use Hotspots to test again. If the problem remained, you please to create a new thread on Cilk+ forum (http://software.intel.com/en-us/forums/intel-cilk-plus). I think this is not the VTune(TM) Amplifier XE 2013 issue.

Thank you for your reponse.
I have another question : Whad does it means the %CPU time on the top down tree for the "_Cilkrts_worker_stub" ?
It means the % of synchronisation between threads, communication, etc ?

"_Cilkrts_worker_sub" indicates that your code entered the entry of Cilk+ and it will call all Cilk+'s functions in runtime libraries. In other word, it is the root of all functions in Cilk+ libraries.

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