Re: Using Mosix: How to do 100 simulation runs, 7 at a time

Tony Travis <[email protected]>
Newsgroups gmane.linux.cluster.openmosix.general
Message-ID <[email protected]>
Matt W wrote:
> 
> Greetings,
> 
> Im trying to help out a user to kick of a long running job of 100
> compute-intensive runs, but only want to run no more than 7
> of them at any given time on the cluster.
> 
> Can someone comment on a good way to accomplish this on the mosix cluster?

Hello, Matt.

You could do it with a 'semaphore', which is one method of controlling 
access to a limited resource - You would need a wrapper to check the 
semaphore and start jobs. When a job runs, the wrapper increments the 
semaphore and you don't permit more than 7 instances to start. When a 
job ends, the wrapper should decrement the semaphore - any jobs that are 
blocked waiting for the semaphore will run when they poll the semaphore 
and get a value of less than 7.

> Sample code would be great.

Yes, it would but I don't have any ;-)

Seriously, though I'm interested in doing something similar myself and 
I've got as far as thinking about how to do it without using a DRM 
(Distributed Resource Manager) like SGE (Sun Grid Engine) or similar. 
The strategy I've outlined is how access to limited resources is done at 
the kernel level...

> BTW: We have 20 node Debian Sarge OpenMosix Cluster of XEON
> and OPTERON nodes running the 2.4.26 SMP kernel + libATA patch

We have a 64-node Athlon cluster with Opteron servers running Red Hat 9 
with an openMosix kernel, but I'm in the process of migrating to Debian.

Best wishes,

	Tony.
-- 
Dr. A.J.Travis,                     |  mailto:[email protected]
Rowett Research Institute,          |    http://www.rri.sari.ac.uk/~ajt
Greenburn Road, Bucksburn,          |   phone:+44 (0)1224 712751
Aberdeen AB21 9SB, Scotland, UK.    |     fax:+44 (0)1224 716687


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