[GE users] Difference in number of allocated and execution slots with PE: Wall clock time in loose and tight intregration

Azhar Ali Shah aas_lakyari at yahoo.com
Fri Apr 25 10:01:47 BST 2008


Many thanks Reuti.
There is also another related issue:

with daemonless smpd method using SSH (loosely integrated) gives following wall
clock time s for 3 jobs that require 4 processors:

J1:  00:30:34
J2:  01:17:53
J3:  04:02:18

when these jobs are run with tight integration (daemon based smpd) again
requiring 4 processors, the wall clock time changes to:

J1: 00:34:44
J2: 02:58: 51
J3: 10: 31:44

Though the wall clock time for J1 is approximately same what makes J2 and J3 to
differ so long?

Thanks again for your time and help

Azhar




--- On Thu, 4/24/08, Reuti <reuti at staff.uni-marburg.de> wrote:
      From: Reuti <reuti at staff.uni-marburg.de>
      Subject: Re: [GE users] Difference in number of allocated and
      execution slots with PE
      To: users at gridengine.sunsource.net
      Date: Thursday, April 24, 2008, 1:01 PM

Hi,
Am 24.04.2008 um 13:41 schrieb Azhar Ali Shah:
> Using SGE with MPICH2-1.0.7rc2 (smpd daemon based method) on my 6  
> node cluster with 9 processors in total, when I submit a job  
> requesting 9 processors, it gets run on only on 7 (including one  
> master), as I could verify from qacct command.
>
> I cann't understand why the rest of two processors don't take part
 
> in computation?
with the daemon based method you get only one
 entry for the daemon  
per node (hence 6) plus one entry for the master task (i.e. the job  
script) of this parallel job (so 7 in total, as I would expect it).  
This is the reason to have the setting "job_is_first_task FALSE" in  
the daemon based method. In qacct you should see for this "master"  
entry (usually the last one) nearly no computation (i.e. CPU) time  
reported.
> Though when 4 processors are requested the job runs on 4 slaves  
> plus one master i.e total of 5 processors in use!
Same as above, correct output. Although depending on the actual load  
of the cluster you might get less entries, as there is only one  
daemon necessary even when two processes for one job are running on  
this slave node.
> Any ideas on how to get arround this?
Nothing to worry about, all seems to be in best order :-)
-- Reuti
> Thanks
>
 Azhar
>
>
>
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