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

Gareth.Williams at csiro.au Gareth.Williams at csiro.au
Thu Mar 31 16:09:08 MDT 2011


> -----Original Message-----
> From: Gabe Turner [mailto:gabe at msi.umn.edu]
> Sent: Thursday, 31 March 2011 7:02 AM
> To: Torque Users Mailing List
> Subject: Re: [torqueusers] X forwarding in torque very slow (qsub -X)
> 
> 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

If you want a workaround, it may be acceptable at your site to instead do:
qsub -v DISPLAY=$DISPLAY
and access the display you have set up on the login node.  This will probably work if you have a shared home directory and the xauth entry is accessible, but the DISPLAY needs to be set to a 'network accessible' (accessible for a compute node) like mycluster:10 or mycluster.mydomain:10 but not localhost:10 or just :10 (though you may be able to doctor the xauth and DISPLAY setting to work around that too).  The sshd_config X11UseLocalhost(=)no setting comes in handy.

- Gareth


More information about the torqueusers mailing list