yade-dev team mailing list archive

[Bruno Chareyre <bruno.chareyre@xxxxxxxxxxxxxxx>]

I can't say a thing: I don't know what is the capillary contribution to
those curves.
The capillary stress at a given point would be a better test. Half way
before peak, for instance.
Bruno

On 04/12/14 20:37, Jerome Duriez wrote:
> The "attached figures"... Sorry for that...
>
>
> ------------------------------------------------------------------------
> *From:* Yade-dev
> [yade-dev-bounces+jerome.duriez=ucalgary.ca@xxxxxxxxxxxxxxxxxxx] on
> behalf of Jerome Duriez [Jerome.Duriez@xxxxxxxxxxx]
> *Sent:* December 4, 2014 12:27 PM
> *To:* yade-dev@xxxxxxxxxxxxxxxxxxx
> *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...
>
> 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
> [yade-dev-bounces+jerome.duriez=ucalgary.ca@xxxxxxxxxxxxxxxxxxx] on
> behalf of Bruno Chareyre [bruno.chareyre@xxxxxxxxxxxxxxx]
> *Sent:* December 4, 2014 10:56 AM
> *To:* yade-dev@xxxxxxxxxxxxxxxxxxx
> *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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-- 
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Bruno Chareyre
Associate Professor
ENSE³ - Grenoble INP
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