Hi - in general multi-cpu "supercomputers" like this have no way of
auto-parallelising tasks such as this; you would have to re-write the
code. This is exactly what you would expect, and yes the SGI processors
will probably be a lot slower than the fastest Intel chips.
Thanks, Steve.
On Fri, 2 May 2003, Darren Schreiber wrote:
> In an attempt to speed things up, I tried using FSL on a supercomputer
> we have on campus. Here is a view from "top":
>
>
> IRIX64 inire 6.5 IP35 load averages: 1.00 0.71 0.32 03:09:35
> 184 processes: 180 sleeping, 2 zombie, 2 running
> 64 CPUs: 98.4% idle, 1.6% usr, 0.0% ker, 0.0% wait, 0.0% xbrk,
> 0.0% intr
> Memory: 32G max, 31G avail, 20G free, 4096M swap, 4096M free swap
>
> PID PGRP USERNAME PRI SIZE RES STATE TIME WCPU% CPU%
> COMMAND
> 122536 122279 dschreib 20 122M 117M run/36 2:00 11.7
> 99.86 film_gl
> 122555 122555 dschreib 20 2288K 1344K run/32 0:00 0.4
> 0.83 top
>
>
> What I find interesting is that I am leaving the 64 processors 98%
> idle, while the CPU% used by film is 99.86%.
>
> Is this because FSL is working hard on one processor, but leaving the
> others inactive? Is there anything I can do here to speed things up?
>
> As it is, it looks like my happy little laptop can get the first level
> analyses done in about the same amount of time.
>
> Darren
>
Stephen M. Smith MA DPhil CEng MIEE
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
|