Hello,
yes, you're right, I continued using the C-syntax. Now it looks much better.
One question about this to make it perfect: If i write...
forall part in field.p {
part.f.x = 0.0;
part.f.y = 0.0;
part.f.z = 0.0;
}
...how can I get the index of "part" within the array "p"?
bye
Zitat von Ben Harshbarger <[email protected]>:
> Hi Michael,
>
> Looking through your code I saw that you were passing classes as arguments
> with the ‘ref’ intent. Chapel classes are passed as references by default,
> so I don’t think you need the ref intent in most of those functions:
>
> // this should be fine
> proc calc_force(parts : ParticleField) { … }
>
> Something else you can do to improve your code’s performance and
> readability is to iterate directly over an array instead of its underlying
> domain:
>
> forall part in field.p {
> part.f.x = 0.0;
> part.f.y = 0.0;
> part.f.z = 0.0;
> }
>
> // instead of
>
> forall i in 0..field.num_parts-1 {
> field.p[i].f.x = 0.0;
> field.p[i].f.y = 0.0;
> field.p[i].f.z = 0.0;
> }
>
>
>
> Let me know if you have any additional questions.
>
> -Ben
>
>
> On 8/18/14, 11:18 AM, "Michael Dietrich"
> <[email protected]> wrote:
>
>> Hello,
>>
>> okay, if you want to you can read through the code [1]. :)
>> For comparation it includes the program in C which I successfully
>> parallelized with MPI and the same program in Chapel.
>> I hope I didn't forget to comment important lines. If anything is
>> unclear just ask me.
>>
>> Please consider the code won't win a beauty contest (especially the
>> one in C) but at least my Chapel code is more readable than the code
>> in C mostly written by the responsible employee. ;)
>>
>> bye
>>
>> [1] http://www-user.tu-chemnitz.de/~michd/fish.tar.gz
>>
>>
>> Zitat von Lydia Duncan <[email protected]>:
>>
>>> Hi Michael,
>>>
>>> I think it will be difficult for us to offer further suggestions
>>> without looking at the code ourselves, would you be comfortable
>>> sending it?
>>>
>>> Lydia
>>>
>>> On 08/18/2014 05:27 AM, Michael Dietrich wrote:
>>>> Hello,
>>>>
>>>> today I compiled my program with the --fast flag.
>>>> Though it made both the serial execution much faster than before, the
>>>> parallel one became even slower compared with the serial. I'm still
>>>> trying to find any possible mistakes within my code but I can't find
>>>> any. Any suggestions?
>>>>
>>>> bye
>>>>
>>>>
>>>>
>>>> Zitat von Tom MacDonald <[email protected]>:
>>>>
>>>>> Hi Michael,
>>>>>
>>>>> Without --fast the compiler generates runtime checks, which slows
>>>>> down execution time.
>>>>>
>>>>> Please compile with the --fast flag and see how much execution
>>>>> time improvement there is.
>>>>>
>>>>> Thanks
>>>>>
>>>>> Tom MacDonald
>>>>>
>>>>> On Fri, 15 Aug 2014, Tom MacDonald wrote:
>>>>>
>>>>>> Hi Michael,
>>>>>>
>>>>>> Thank you for your interest in Chapel! It's good to hear you are
>>>>>> studying high performance programming languages.
>>>>>>
>>>>>> Are you compiling your Chapel program with the --fast option?
>>>>>>
>>>>>> We need to know that before looking deeper.
>>>>>>
>>>>>> Thanks
>>>>>>
>>>>>> Tom MacDonald
>>>>>>
>>>>>> On Fri, 15 Aug 2014, 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
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ---------------------------------------------------------------------
>>>>>>> ---------
>>>>>>> _______________________________________________
>>>>>>> Chapel-users mailing list
>>>>>>> [email protected]
>>>>>>> https://lists.sourceforge.net/lists/listinfo/chapel-users
>>>>>>>
>>>>>>
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>>>>>>
>>>>
>>>>
>>>>
>>>>
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