Re: Time for merging of THnSparse

From: Axel Naumann <Axel.Naumann_at_cern.ch>
Date: Wed, 21 Jul 2010 12:06:37 +0200


Hi Marian,

I cannot reproduce this. For me running time stays constant; it's simply a function of the number of filled bins of the histogram that is being merged.

Except for when my machine starts to swap memory because the merged THnSparse is growing too large. Might that be your case?

Cheers, Axel.

Marian Ivanov wrote on 07/19/2010 09:54 AM:
> Hallo Axel
>
> Finally I managed to use new root
> Version 5.27/04 29 June 2010
>
> CPU time for merging is smaller (in comparison with 5.26.xxx) but still
> I observe non linear time dependence of merging.
> See attached picture - time to merge versus merge number.
>
> Because of this, I'm doing merging recursively, in chunks of n merging,
> but I think that
> you can try to implement THnSparse in non sparse mode in case of
> occupancy > something.
> I expect it will save time, and also disk space. As we discussed before.
>
> Ciao
> Marian.
>
>
Received on Wed Jul 21 2010 - 12:06:47 CEST

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