So, there is some comparisons in the attached figures. In the figures with "par" suffix you will find results from two simulations with j4: - one with the updated code with parallel loops over interactions - the other one with previous code.
In the figures with "_j" suffix there is results from: - one simulation with j1 - one of the two j4 simulations quoted previously I consider these figures do not show anything "bad".. As for the fusion detection, unfortunately I can not say anything (I did not really give a look into this part yet). What would you think then if I remove some of the parallel loops, keeping only the one for the block from l. 174 and 203 ? This block mainly use addForce() function, that is thread safe. Before that, it might modify the computed fCap in fusion case. With what I understand from openMP, it seems that nothing bad might happen here, does it ? (I guess each interaction is accessed only from one thread) Jerome ________________________________ From: Yade-dev [[email protected]] on behalf of Bruno Chareyre [[email protected]] Sent: December 4, 2014 10:56 AM To: [email protected] Subject: Re: [Yade-dev] [Branch ~yade-pkg/yade/git-trunk] Rev 3486: Parallelization of interaction loops in Law2_..._Capillarity (which is in fact not a LawFunctor h... On 04/12/14 18:46, Bruno Chareyre wrote: On 03/12/14 22:57, Jerome Duriez wrote: Hi, General discussions apart, what is the problem with this commit ? I don't know if there is a problem or not. I guess you checked that it gives the same result before/after and -j1/-jN. Did you check also the fusion detection? After a quick look, there is a problem here: https://github.com/yade/trunk/blob/master/pkg/dem/Law2_ScGeom_CapillaryPhys_Capillarity.cpp#L117 This insert() method is not thread-safe. If two threads are inserting at the same time the result is undefined. It needs a "critical" clause (this will surely kill the performance) or a better design. B
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