Hello Clemens,

thank you for the material. I will get back to that once my advisor  
tells me what I actually have to write about in my thesis. By now he  
just told me to implement the given program and went on vacation. :)
I am not pressed for time, just want to solve this problem at first. ;)

bye


Zitat von Clemens Grelck <[email protected]>:

> Hi Michael,
>
> If you are interested in how modern parallel programming languages
> deal in particular with the particle simulation problem, I recommend
> you to read the following special issue of the journal Concurrency
> and Computation: Practice and Experience:
>    http://onlinelibrary.wiley.com/doi/10.1002/cpe.v26.4/issuetoc
>
> The actual special issue papers are towards the end of the table of
> contents. These paper papers originate from phase 2 of the SICSA
> multicore challenge that was about implementing an n-body simulation
> in anyone's favourite multicore language and comparing performance.
>
> Happy reading,
>    Clemens
>
> On 8/15/14 4:52 PM, Michael Dietrich wrote:
>> Hello,
>>
>> I'm working with Chapel due to my bachelor thesis about high
>> performance programming languages. My current task is to implement a
>> particle simulation program of which I already have the code in C. It
>> includes two possible algorithms for calculating the force acting onto
>> the particles: A simple but ineffective one and the
>> Barnes-Hut-Algorithm [1] which is much faster but a bit more
>> complicated. The other calculations aren't that complex so for me only
>> the calculation of force is important.
>>
>> I implemented the simple algorithm at first. For comparing the serial
>> and parallel execution time I surrounded everything with a
>> serial-statement, evaluating a bool variable I have to set in the
>> command line. I didn't implement the multi locale improvement yet so
>> it runs only on a dual core PC, using forall-loops. Finally the
>> parallel one only needed half of the time of the serial, yay.
>>
>> I continued with Barnes-Hut. This one was a bit more work because the
>> maintenance of the tree-structure leaves a lot of opportunities for
>> mistakes. After a bit more time it was working as well.
>> My issue is about the parallel execution time of this algorithm. Like
>> in the other one I replaced the crucial for-loop with a forall-loop
>> (the serial-statement surrounds the whole program). The problem is,
>> that the parallel execution time is similar to the serial one,
>> sometimes even longer.
>> Of course I don't want you to read through all my code, but could you
>> tell me some possible reasons, why this effect may occur?
>>
>> thank you very much
>> bye
>> Michael
>>
>>
>> [1] http://beltoforion.de/barnes_hut/barnes_hut_en.html
>>
>>
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>> https://lists.sourceforge.net/lists/listinfo/chapel-users
>
>
> --
> ----------------------------------------------------------------------
> Dr Clemens Grelck                                     Science Park 904
> University Lecturer                                   1098XH Amsterdam
>                                                             Netherlands
> University of Amsterdam
> Institute for Informatics                        T +31 (0) 20 525 8683
> Computer Systems Architecture Group              F +31 (0) 20 525 7490
>
> Office C3.105                               www.science.uva.nl/~grelck
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