[torqueusers] X forwarding in torque very slow (qsub -X)

Gabe Turner gabe at msi.umn.edu
Wed Mar 30 14:02:11 MDT 2011

On Wed, Mar 30, 2011 at 06:10:14PM +0200, Brunet Pierre-Marie wrote:
> Hi there, 
> I'm facing a strange problem when I launch an interactive job with X11
> forwarding "qsub -X -I" :
> When I use a GUI, it runs much more slowly than the same GUI opened in a
> "ssh -X" context. 
> Client PC ==ssh -X==> Torque client (front node) ==ssh -X==> cluster
> node : OK
> Client PC ==ssh -X==> Torque client (front node) ==qsub -X -I==> cluster
> node : NOK
> For example, the menu in Matlab is very jerky but I don't have this
> problem when I'm connected to the node throught ssh -X.
> "qsub -X -I" seems to add a lot of latency in the loop.
> The configuration is : 
> - OS = RedHat5 (server and nodes)
> - Torque = 2.4.11

I'll second this report; we're also seeing it.  We're also running 2.4.11,
but haven't tested with any other versions.  Specific apps where we see a
marked difference are Avizo and Ansys.  I'm suspecting that some apps will
perform better than others when using qsub -X.  For example, with Matlab
and Tecplot, we see very little difference in responsiveness, if any,
between qsub -X and ssh -X.

Gabe Turner                                             gabe at msi.umn.edu
HPC Systems Administrator,
University of Minnesota
Supercomputing Institute                          http://www.msi.umn.edu

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