On Dec 28, 2005, at 1:17 AM, Kawai wrote:
> i can sucessfully run lamboot to boot all the machines,
> but it seems that the time for booting all machines is longer that
> before.
Longer than before on the same machine, or on a different machine?
lamboot is not computationally intensive and (as far as I've ever
seen) the time lamboot takes is independent of compiler used or
compiler optimizations used. However, lamboot's time to completion
*is* dependent on the time it takes to start the remote lamd
processes. Some versions of Open SSH are slower than others (usually
not so much because of changes to the source code, but because of
changes to configuration settings). If your network is not totally
configured (A records matching PTR records) or you have host entries
in /etc/hosts on one cluster and not in the other, those can all make
a difference in startup times. My guess is that the slowdown is due
to something other than LAM/MPI in this particular situation.
Now, if you are seeing increases in time to complete your parallel
codes, that might be cause for concern (again, however, networks
between the clusters may be different, so comparisons can be difficult).
> Therefore, i want to ask:
> 1) what should i modify if i want to compile LAM on EM64T
Nothing - from the part I cut out, everything looked ok. You don't
have to set LAMHF77 (and it's probably a better idea not to), as LAM
will use the Fortran compiler used during configure. Since not all
Fortran compilers are the same, it's usually a good idea not to set
LAMHF77, for the day you decide to use the PGI compilers instead of
the Intel compilers and suddenly (and inexplicably) have missing
symbols all over the place ;).
> 2) I have also installed and updated LAM7.1.1-7 released from FC4
> website,
> %which lamboot
> /usr/bin/lamboot
> but i have to configure the LAM to use intel FC9.0 ifort,
> how can i the configure. As i install LAM by
> %yum install lam*
> the default setting is installed and i can't make any configuration.
You would not be able to use the LAM release from the FC4 website, as
it is configured to use the GNU compiler chain. You could, however,
download the Source RPM, extract the SPEC file, and modify it to use
ifort instead of g77. That, however, is beyond the scope of this
mailing list.
Hope this helps,
Brian
--
Brian Barrett
LAM/MPI developer and all around nice guy
Have a LAM/MPI day: http://www.lam-mpi.org/
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