David van der Spoel spoel at xray.bmc.uu.se
Wed Jun 13 10:14:37 PDT 2001

On 13 Jun 2001, Joey Raheb wrote:

>I've posted this message up a couple of times already with no response, I'll
>try one more time.  I would like to try something new with PBS.  We will soon
>be adding more computers to our cluster and therefore will require another
>switch.  Since the bottleneck in the communication exists in the switch-switch
>communication (1000 MB/s duplex) we would like to run all parallel jobs within
>the same switch since bandwidth is near theoretical max within the switch.  My
>idea was to create two execution queues named switch1 and switch2 (each would
>only send jobs to nodes on each respective switch) and one route queue which
>would direct jobs to either switch1 or switch2 depending on the number of
>nodes requested and the free number of nodes available.  I thought there would
>be an easy way to do this, but I am finding that there might not be.  Maybe
>PBS is not the correct queueing system, does anybody have any suggestions or
>ideas of how I can implement the above??

You are definitely going to write your own scheduler, but then it 
shouldn't be very hard. Let the scheduler logic just take care of that the 
nodes you assign a certain job are all on one switch. You can still do
with a single queue, although you could give the nodes attributes like
group1, group2 etc. I run a single queuing system with three queues (low,
medium, high) spread over two machine types (PC/Alpha). There is only one
scheduler, and it runs just fine.

Groeten, David.
Dr. David van der Spoel		Biomedical center, Dept. of Biochemistry
s-mail:	Husargatan 3, Box 576,  75123 Uppsala, Sweden
e-mail: spoel at xray.bmc.uu.se	www: http://zorn.bmc.uu.se/~spoel
phone:	46 18 471 4205		fax: 46 18 511 755

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