Re: Question about domain_Decomposition() and force_update_len()

From: Ali Snedden <asnedden_at_nd.edu>
Date: Mon, 24 Feb 2014 16:56:33 -0500

Thanks!

~Ali


On Mon, Feb 24, 2014 at 3:40 PM, Volker Springel <volker_at_mpa-garching.mpg.de
> wrote:

>
>
> On Feb 23, 2014, at 8:38 PM, Ali Snedden wrote:
>
> > Hello,
> >
> > At every timestep the a domain Decomposition occurs (calling
> domain_decompose()) or the Nodes[*].len gets updated in force_update_len().
> This occurs domain_decompose() is controlled by the conditional
> >
> > if(All.NumForcesSinceLastDomainDecomp > All.TotNumPart *
> All.TreeDomainUpdateFrequency)
> >
> > force_update_len() is controlled by the conditional (see predict.c)
> >
> > if(All.NumForcesSinceLastDomainDecomp < All.TotNumPart
> *All.TreeDomainUpdateFrequency)
> >
> > However if All.NumForcesSinceLastDomainDecomp = All.TotNumPart
> *All.TreeDomainUpdateFrequency, neither the domain_decompose() is run nor
> are the Nodes[*].len updated in force_update_len(). Is this the expected
> behavior?
>
> Hi Ali,
>
> This is a bit hideous, but things should be still be fine.
>
> If you have All.NumForcesSinceLastDomainDecomp = All.TotNumPart
> *All.TreeDomainUpdateFrequency such that the dynamic tree updates are not
> done, you will still get a domain decomposition for the next force
> calculation followed by a reconstruction of the tree. The reason is that in
> between find_next_sync_point_and_drift() is called, where
> NumForcesSinceLastDomainDecomp is incremented by the number of active
> particles in the next step. This will be at least 1, so that then the
> condition All.NumForcesSinceLastDomainDecomp > All.TotNumPart *
> All.TreeDomainUpdateFrequency is fulfilled.
>
> Best regards,
> Volker Springel
>
>
>
>
> > I recently encountered such a situation when the values were
> >
> > All.NumForcesSinceLastDomainDecomp = 11000
> > All.TotNumPart = 110000
> > All.TreeDomainUpdateFrequency = 0.1
> >
> > Thank you for your time.
> >
> > Sincerely,
> > Ali
> >
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>
>
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Received on 2014-02-24 22:56:40

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