[GE users] Comparison of MPI Job Runtimes with and without SGE

Waseem Ahmad Waseem.Ahmad.1 at Sun.COM
Wed Aug 11 23:01:44 BST 2004


Reuti!
     I am using ch_p4. mpich-1.2.5.2,.. rsh. I did not know about the 
usefulness of serv_p4.i will defintely try it out.
I would assume that both SGE and MPICH spawns jobs in similar fashion 
through rsh. In fact tight integration may pay a little more cost 
because of the extra cost of exceuting the rsh wrapper. is'nt it?

Reuti wrote:
> Hi,
> 
> 
>>   I was running an MPI job on my solaris cluster. I found out that the 
>>job actually takes less amount of time to execute with MPICH tightly 
>>integrated with SGE than when it runs through plain MPICH only. Note 
>>that there is no other user load on the cluster. and this MPI job is 
>>only user job running on the cluster. and most impoprtantly i am feeding 
>> eaxctly the same set of machines to the job (when it running through 
>>plain MPICH) as SGE_tight integration makes the job run on.
>>I would assume, given that both times job is run on the same set of 
>>nodes, SGE should incur more cost as comapred to MPICH?. Any idea ?
> 
> 
> what MPICH device and version are you using: ch_p4, Myrinet, ... mpich 
> 1.2.5.2/1.2.6 ... ssh/rsh
> 
> Interesting, I never thought about this. I depends on the amount of "rsh" calls 
> I could imagine. If you have a parallel job, where all the nodes are getting 
> only one rsh-command and calculating for hours, then there shouldn't be a 
> difference. When you have many small steps with many rsh-calls, a rsh-daemon 
> has to be started by SGE with each qrsh. Maybe this is faster than the login in 
> to the default daemon (i.e. going through inetd.conf ... starting session)
> 
> With the ch_p4 device, there is the possibility to speed up the creation of the 
> sessions by starting a server on the nodes (serv_p4). Can you try this (without 
> SGE)?
> 
> I'm curious, whether there is also a difference.
> 
> Cheers - Reuti
> 
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