AMBER Archive (2002)

Subject: Re: "number of processors must be a power of two"

From: Jim (jcanon_at_yaw.org)
Date: Tue Aug 06 2002 - 12:29:48 CDT

Yes, that helped. Thank you. Looks like I might try something besides
MPICH. Performance is definately suffering with that compile option.
Thanks again.

Jim

> On Tue, Aug 06, 2002, Jim wrote:
> >
> > number of processors must be a power of 2, and no greater than 128:
>
> This is a message generated by sander; with the (default) BTREE
option in
> version 7, the number of processors indeed must be a power of 2. It
has
> nothing to do with your MPI implementation.
>
> You can remove this restriction by adding "-DnoBTREE" to your
MACHINEFLAGS
> variable (in the MACHINE file) and re-compiling. This change might
not
> even cost much in performance if your MPI has a good implementation
of global
> gather/scatters (MPICH does not have very efficient implementations
here.)
>
> ..hope this helps...dac
>
> --
>
> ==================================================================
> David A. Case | e-mail: case_at_scripps.edu
> Dept. of Molecular Biology, TPC15 | fax: +1-858-784-8896
> The Scripps Research Institute | phone: +1-858-784-9768
> 10550 N. Torrey Pines Rd. | home page:
> La Jolla CA 92037 USA | http://www.scripps.edu/case
> ==================================================================
>
>
> 

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