[torqueusers] strange behaviour of ppn

pat.o'bryant at exxonmobil.com pat.o'bryant at exxonmobil.com
Wed Nov 17 14:50:45 MST 2010



Govind,
     Go to the Adaptive Resource web page and get the Torque manual in PDF
format. Next search for "tpn" which stands for "task-per-node". There is an
explanation of how "ppn" and "tpn" are different.
>From your test cases it is as though your jobs are being interpreted in a
task fashion and not a node fashion. So, when the statement "nodes=3:ppn=1"
is made, this is a request for (3 x 1) tasks instead of what you intended.
Try this instead: "nodes=3,tpn=1". The request says "3 nodes" with "1 task
per node". Note that there is a "comma" after the "nodes" values and not a
":". Hopefully you will get a better result. The use of ppn can be
confusing.
       Thanks,
        Pat


J.W. (Pat) O'Bryant,Jr.
Business Line Infrastructure
Technical Systems, HPC




                                                                           
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Hi Brian,

I do'nt want to block a complete node for a single job.
My requirement is to request multiple processor on different nodes which is
not working at the moment.

Thanks
Govind


On Mon, Nov 15, 2010 at 5:53 PM, Andrus, Brian Contractor <bdandrus at nps.edu
> wrote:
  Govind,

  You may want to add:

  #PBS -l naccesspolicy=singlejob

  This will cause allocation to be a single job per node.
  Given your resource request, you do not specify you need exclusive use of
  the node, so as far as torque is concerned, there are processors
  available to be assigned to jobs, which it does.

  Brian Andrus



  ________________________________

  From: torqueusers-bounces at supercluster.org on behalf of Govind Songara
  Sent: Fri 11/12/2010 8:25 AM
  To: Torque Users Mailing List
  Subject: [torqueusers] strange behaviour of ppn


  Hi,


  I am not expert on torque configurations, so might something wrong with
  configurations.
  I am seeing a strange behaviour of ppn variable.
  My nodes config is something like
  node01 np=4
  node02 np=4

  snippet of maui config
  JOBNODEMATCHPOLICY     EXACTNODE
  ENABLEMULTINODEJOBS   TRUE
  NODEACCESSPOLICY         SHARED


  snippet of queue config        resources_available.nodect =
  65        resources_assigned.nodect = 5        resources_default.nodes = 1

  sample script
  ------------------------------------
  #PBS -q long
  #PBS -l nodes=2:ppn=1

  echo This jobs runs on the following processors:
  echo `cat $PBS_NODEFILE`
  NPROCS=`wc -l < $PBS_NODEFILE`
  echo This job has allocated $NPROCS processors
  hostname
  ------------------------------------

  Below is my result in the tables



  nodes

  ppn

  no. process run (hostname)

  no. pf processor allocated

  3

  1

  1

  3

  3

  2

  1

  2

  3

  3

  1

  3

  3

  4

  1

  4

  In case 1, it gives 3 processor on same node which is incorrect, it
  should give 1 processor on 3 different nodes
  In case2, it give only 2 processor on same node, it should 2 processor on
  3 different nodes (total 6 processor) and similar behaviour with the last
  tow cases.
  In all the cases the hostname command run only once, which should run at
  least on total number of allocated processors.


  Due to this strange behaviour i can not run mpi jobs correctly, kindly
  advise on this problem.

  TIA

  Regards
  Govind






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