Priciple of OpenMP

General OpenMP discussion

Priciple of OpenMP

Postby hse05013 » Tue Jul 22, 2008 5:16 am

Hello!

I have searched in the www to find information about the principle, the concept or the operation mode of OpenMP. The problem is, that a have not found a good explanation. I already know about the Fork-Join-Principle, but this is too less information for me.

Has anybody a link or something else for me, where i can read about the concept of OpenMP. I searched also for a picture that can help me to understand the functionality of OpenMP.

Is it true, that the directives uses the tphread-fuctions?

I also want to have information about the syncronisation model of OpenMP. Is it true that there are no signals or wait-functions?

A lot of questions. I hope, someone can help me.

Thanks in advance
hse05013
 
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Re: Priciple of OpenMP

Postby ejd » Tue Jul 22, 2008 7:48 am

hse05013 wrote:
I have searched in the www to find information about the principle, the concept or the operation mode of OpenMP. The problem is, that a have not found a good explanation. I already know about the Fork-Join-Principle, but this is too less information for me.

Has anybody a link or something else for me, where i can read about the concept of OpenMP. I searched also for a picture that can help me to understand the functionality of OpenMP.

Over the last few years there have been quite a number of papers and articles written describing various aspects of OpenMP implementations. Since I don't know what level of information you are looking for, it is hard to give you an exact reference. Have you looked at the OpenMP web site under presentations? There is a presentation from Barbara Chapman (OpenMP under the hood) that talks about the University of Houston's OpenMP implementation. There are also several tutorials and technical articles that might give you the information you are looking for. If this doesn't cover what you want, please try posting here again with more specifics as to what you are looking for.

hse05013 wrote:
Is it true, that the directives uses the tphread-fuctions?

Most implementations are based on posix threads or pthreads.

hse05013 wrote:
I also want to have information about the syncronisation model of OpenMP. Is it true that there are no signals or wait-functions?

For the most part, this is true. A user can do his own synchronization using flush or locks, but it has turned out to be quite a "can of worms" since we have found that most users don't really understand all the problems and pitfalls. The omp-lang committee that decides what to put into the OpenMP spec has looked at this before and rejected adding things like semaphores. However, this opinion has been changing and I am sure that the issue will be taken up again in the future.
ejd
 
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Re: Priciple of OpenMP

Postby hse05013 » Wed Jul 23, 2008 12:46 am

Hi!

Thanks for your answer, ejd.

I have found the presentation from Babara Chapman. I have also the book "Using OpenMP".

The reason, why I searched for the information is that i have to write about 30 sites as a final work for school. I have to work out the differences between OpenMP and "normal" paralism with CreateThread under Windows.

To explain the idea of OpenMP, I need a "big picture" that i can explain, HOW OpenMP works.

An other question: Is it possible, to solve the problem of dining philosophers with openMP? I think it could work with lock-synchronisation?
hse05013
 
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Re: Priciple of OpenMP

Postby ejd » Wed Jul 23, 2008 5:33 am

hse05013 wrote:I have found the presentation from Babara Chapman. I have also the book "Using OpenMP".

While I have not yet had a chance to read this book, I know the authors and their work and I am sure that they have done a good job. It is definitely the most current book on the topic and I am sure it has a lot of good information on OpenMP that can help you.

hse05013 wrote:The reason, why I searched for the information is that I have to write about 30 sites as a final work for school. I have to work out the differences between OpenMP and "normal" parallelism with CreateThread under Windows.

I am not sure I understand what you mean about "30 sites" - but then I don't have to. I am glad that you said "normal" parallelism under Windows, because that (windows) is just one model (as opposed to say pthreads).

hse05013 wrote:Another question: Is it possible, to solve the problem of dining philosophers with OpenMP? I think it could work with lock-synchronisation?

While I haven't tried solving this problem myself, I see no reason it couldn't be solved using OpenMP. In fact, I just did a quick web search and I see that it has been used in college programming courses as an assignment to use OpenMP.
ejd
 
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Re: Priciple of OpenMP

Postby hse05013 » Thu Jul 24, 2008 4:45 am

"30 sites" should be "30 pages" - sorry about my bad english

What I am still be looking for is a picture (or an exeplaric sceth) where I can see an overwiew about the priciple of parallelism of OpenMP. On the basis of this picture I should explain the priciple.

Did you know, where I can find such a picture?
hse05013
 
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