[torqueusers] qsub -X much slower than ssh -X

Lawrence Lowe L.S.Lowe at bham.ac.uk
Thu Aug 14 03:09:46 MDT 2008

Hi, I saw this old thread and have observed much the same thing myself: 
bigger latencies when using qsub -IX versus ssh -X, again with MatLab:

                                 local    qsub-IX  ssh-X

start to matlab "Ready"         9 sec    23 sec   21 sec

start to matlab "Ready" repeat  4 sec    14 sec    9 sec

time to show klein image     <0.5 sec    10 sec    3 sec

latency after window switch  <0.5 sec     9 sec   <1 sec

These used an otherwise-empty node.

Our cluster is running Torque 2.1.6. Has anything been fixed which would 
suggest an upgrade to 2.3.2? I can't see anything that hints at that in 
the CHANGELOG for 2.3.2.

It's as if packets aren't being pushed at the appropriate time, in one 
direction or the other. But that's only a wild guess. I haven't found 
another application myself which has the same bad window-switch latency 
(but I'll keep looking).

Any thoughts, anyone?

Thanks, Lawrence.

Tel: 0121 414 4621    Fax: 0121 414 6709    Email: L.S.Lowe at bham.ac.uk

On Mon, 11 Feb 2008, Garrick Staples wrote:

> On Mon, Feb 11, 2008 at 12:41:55AM -0500, Prakash Velayutham alleged:
>> On Feb 11, 2008, at 12:24 AM, Garrick Staples wrote:
>>> On Sun, Feb 10, 2008 at 10:50:20PM -0500, Prakash Velayutham alleged:
>>>> Hello All,
>>>> I recently noticed that performance of GUI-based applications like
>>>> Matlab are much slower during a qsub -X session than a ssh -X
>>>> session.
>>>> Matlab takes about 6 seconds to start up using qsub -X, but only 2
>>>> seconds using ssh -X.
>>>> Any idea why? What should I check in my Torque server/MOM
>>>> configuration?
>>> There wouldn't be any configs for this.  I'll test tomorrow at work.
>> Hi Garrick,
>> Thanks. I just did a test again and here are the numbers.
>> qsub -I -X to a node asking for all procs (4 in this case). Starting
>> up Matlab (no options/arguments, nothing) takes about 25-28 seconds to
>> get me the GUI with prompt inside Matlab command window.
>> ssh -X to a node which has no job running (with 4 CPUs) and starting
>> up Matlab takes about 10 seconds to bring the GUI with prompt.
>> Sorry about my earlier figures of 6 seconds and 2 seconds. Those were
>> just proportions.
> I'm not able to replicate this result.  I've tried a few different i686 and
> x86_64 nodes and no matter what I do, I get the splash screen in ~2 seconds and
> the main window fully drawn in another ~2-4 seconds.

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