2009/11/4 Václav Šmilauer <[email protected]> > (please reply to the list, not to me) > > I hear that OpenMP is based on Shared Memory Parallel Computing, and > > it needs random accessing to the data (I am not very sure, but just > > hear about that, if I am wrong, please forgive me and tell me the > > right thing, thanks). For my code, the contacts are stored in a list, > > that is not randomly accessable. If it is ture OpenMP needs random > > accessing, then how does YADE do that？Is it ok to run YADE on a > > distributed memory computer architecture, like in Cluster--I saw > > somebody run it on a cluster, but I do not know the cluster > > architecture. Because in a distributed memory architechture, the > > memory is not directlly accessable, which will increase the > > programming difficulty. > > Both InteractionContainer and BodyContainer support integer indices, > i.e. random access. No, you cannot run yadeo n distributed memory as > each core needs access to the whole memory. > > > Currently my speed is 3~4 second to do a iteration for about 100,000 > > particles, and 33 seconds to do an iterations for 988,000 particles. > > I use threads to do the parallel computing, but the speed up is only > > 2.2 times faster (15 seconds for 988,000 particles.). This speed is > > terrible bad, because the dt is in the order of 10^(-7) second for the > > simulation of rock particles. > > How many cores do you have? See > > https://yade.hmg.inpg.fr/index.php/Speed_profiling_using_TimingInfo_and_TimingDeltas_classesto > get exact idea what takes how much time (do "O.timingEnabled=True" before > running the simulation, then "from yade import timing; timing.stats()" once > it's over); the impact of the timing itself is in the order of a few > percents. >
I have 8 cores (2x4 cores), when I use 8 cores (8 threads), the time is (12 seconds), so it is still very bad. But I am sorry I developed my own code (required by my advisor, so I did not use YADE actually, but would like to learn from YADE). I do not know what is the speed for YADE without parallel. yes, the collider is very time consumming, for 1 million particle in my case, it may take more than 10 seconds to do that. and I just do the contact detection every several iterations. the 15 seconds above did not include this 10 seconds. > > Hm, the old link looks better: > > http://yade.wikia.com/wiki/Speed_profiling_using_TimingInfo_and_TimingDeltas_classes > > It is quite possible that the collider takes a lot of time in your case. > Consider using collider stride to run it only sometimes: > https://yade.hmg.inpg.fr/index.php/Insertion_Sort_Collider_Stride > > See examples/concrete/uniax.py, search for > InsertionSortCollider(sweepLength=.05*sphereRadius,nBins=5,binCoeff=5) > and try if that helps. If your simulation is quasi-static, it should > help a lot. Note that the initial sort in InsertionSortCollider takes > very long: http://yade.wikia.com/wiki/Colliders_performace > > (I've been calling for a long time for a better collider, but noone took > the challenge.) > > Cheers, Vaclav > > > _______________________________________________ > Mailing list: https://launchpad.net/~yade-users > Post to : [email protected] > Unsubscribe : https://launchpad.net/~yade-users > More help : https://help.launchpad.net/ListHelp >
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