matlab slowness

predragp at andrew.cmu.edu predragp at andrew.cmu.edu
Sun Feb 8 19:09:55 EST 2015


> I just submitted the paper I was working on (which used a bunch of
matlab simulations) so I've got some free time to help debug this. Not
really sure where to start though as I know very little about matlab
configurations. I suppose something to verify is whether this is an
issue for people not in Neill's group? Is there an autonlab member who
uses a lot of Matlab and would thus be self-interested? I don't know
Chun-Liang Li but I think he uses matlab a lot...
>
> Best,
> Seth
>

I am forwarding you e-mail to users at autonlab.org hopping that somebody can
help.

Most Kind Regards,
Predrag

> On Mon, Feb 2, 2015 at 4:55 PM, Seth Flaxman <flaxman at gmail.com> wrote:
>> Sure. I compared lot1, low1, and lov3:
>>
>> lot1
>>>> bench(5)
>> ans =
>>
>>     2.4679    0.5507    0.2113   38.6126    0.9343    0.8627
>>     2.0373    0.5239    0.1893   30.0908    1.1267    0.6388
>>     1.9278    0.5322    0.1908   32.5306    0.4670    0.7822
>>     3.1591    0.4540    0.2404   41.5550    1.6787    0.9064
>>     3.2059    0.5684    0.1988   25.0799    0.9904    1.6566
>>
>> low1
>>>> bench(5)
>> ans =
>>
>>     1.0779    0.2725    0.1980   22.7329    0.4850    0.5008
>>     1.3599    0.2884    0.2047   26.0477    0.4822    0.4942
>>     1.2960    0.2476    0.1984   27.1457    0.4907    0.4321
>>     1.2698    0.2802    0.1980   15.6125    0.5065    0.4892
>>     1.0454    0.2650    0.1989   10.4417    0.5208    0.5081
>>
>> lov3
>>>> bench(5)
>> ans =
>>
>>     0.3191    0.1766    0.2183    1.7567    0.4645    0.4663
>>     0.2828    0.1779    0.2291    1.5642    0.4895    0.4726
>>     0.3462    0.1938    0.2316    1.8131    0.4603    0.4967
>>     0.2673    0.1896    0.2086    1.7520    0.4870    0.4616
>>     0.3018    0.1713    0.2180    1.8592    0.4587    0.4514
>>
>>
>> Another clue, perhaps, is that if I start up 5 or 6 instances of matlab
then the 5th or 6th will often crash immediately. Matlab seems to do
very weird things with forking. I'm attaching one of those dumps, which
I just got when I tried to run the above.
>> Seth
>>
>> On Mon, Feb 2, 2015 at 4:32 PM,  <predragp at andrew.cmu.edu> wrote:
>>>> Any updates? lov3 and lov4 seem, if anything, to be even slower
especially
>>>> for sparse linear algebra:
>>>>
>>>> lov3:
>>>>>> bench
>>>>     0.6941    0.3787    0.2958   14.4527    0.5514    0.5435
>>>> lov4:
>>>>>> bench
>>>>     1.0360    0.5322    0.2471   16.4350    0.5510    0.6338
>>>>
>>>> Does matlab rely on system packages that are architecture specific, like
>>>> ATLAS?
>>>>
>>>> Best,
>>>> Seth
>>>>
>>>
>>> I have not had chance to work on this stuff but I did little thinking. I
>>> am starting to worry that having SSD HDD in those two computing nodes
what
>>> not such a smart idea. Could you do me a favour and check how the
performance compares to LOW1 which has regular HDD.
>>>
>>> Predrag
>>>
>>>> On Wed, Jan 14, 2015 at 10:31 PM, <predragp at andrew.cmu.edu> wrote:
>>>>
>>>>> > Hah, okay. The fact that it's 0.27 seconds on CMU servers and 33
seconds on low1 seems quite strange.
>>>>> >
>>>>>
>>>>> Just to let you know. I am so busy until the end of next week that
there
>>>>> is not chance I could look into it before than. I apologize for any
inconvenience.
>>>>>
>>>>>
>>>>> Predrag
>>>>>
>>>>> > I found another benchmarking script here:
>>>>> > http://math.ucdenver.edu/~jmandel/matlab/matlab_benchmark.html
>>>>> >
>>>>> > Here's lov3:
>>>>> >
>>>>> > 1. large LU:   0.860
>>>>> > 2. small LU:   0.944
>>>>> > 3. sparse  :   0.302
>>>>> >
>>>>> > Here's low1:
>>>>> >
>>>>> > 1. large LU:   1.813
>>>>> > 2. small LU:   0.526
>>>>> > 3. sparse  :   2.216
>>>>> >
>>>>> > And here's linux.gp.cs.cmu.edu:
>>>>> >
>>>>> > 1. large LU:   0.569
>>>>> > 2. small LU:   0.491
>>>>> > 3. sparse  :   0.176
>>>>> >
>>>>> > Seth
>>>>> >
>>>>> > On Mon, Jan 12, 2015 at 9:29 PM,  <predragp at andrew.cmu.edu> wrote:
>>>>> >>> The warning matlab issues when I start it seems worth
>>>>> investigating
>>>>> >>> further:
>>>>> >>>
>>>>> >>> MATLAB is selecting SOFTWARE OPENGL rendering.
>>>>> >>>
>>>>> >>>                             < M A T L A B (R) >
>>>>> >>>                   Copyright 1984-2014 The MathWorks, Inc.
>>>>> >>>                    R2014b (8.4.0.150421) 64-bit (glnxa64)
>>>>> >>>                              September 15, 2014
>>>>> >>>
>>>>> >>> Warning: MATLAB has disabled some advanced graphics rendering
>>>>> features
>>>>> >>> by switching to software OpenGL. For more information, click <a
href="matlab:opengl('problems')">here</a>.
>>>>> >>>
>>>>> >>> (I'm running matlab at the command-line by ssh'ing into lop1
then low1.)
>>>>> >>>
>>>>> >>> Seth
>>>>> >>>
>>>>> >>
>>>>> >> The fact that we are using Open Graphics Library should not impact
>>>>> your
>>>>> >> code which does non graphics related  computations. The fact that
MathWork
>>>>> >> favours closed binary blobs graphics drivers over OpenGL is very
telling.
>>>>> >> The papers produced by binary blobs are immediately rejected from
>>>>> all
>>>>> >> Mathematics Journals because there is no way to properly referee
>>>>> and
>>>>> >> scrutinize somebody work which uses closed source code.
>>>>> >>
>>>>> >>
>>>>> >> Predrag
>>>>> >>
>>>>> >>
>>>>> >>> On Mon, Jan 12, 2015 at 9:05 PM, Seth Flaxman
<flaxman at gmail.com> wrote:
>>>>> >>>> Fair enough. I think the other server comparisons are most
>>>>> relevant,
>>>>> >>>> but I don't have the full specs on these. Here's what I can
>>>>> tell:
>>>>> >>>>
>>>>> >>>> linux.andrew is running RHEL 6.5 / Matlab R2013a:
>>>>> >>>>
>>>>> >>>> [sflaxman at unix5 ~]$ matlab -nodesktop -nosplash -r "bench(1)"
>>>>> >>>>     0.0631    0.0962    0.3625    0.2873    0.4062    0.0177
>>>>> >>>>
>>>>> >>>> linux.gp.cs is running Ubuntu / Matlab R2014a
>>>>> >>>>
>>>>> >>>>     0.0825    0.1056    0.3558    0.2302    0.3217    0.0124
>>>>> >>>>
>>>>> >>>> phd-serv4.heinz.cmu.edu is running Fedora / R2014a
>>>>> >>>>
>>>>> >>>>     0.0671    0.0844    0.2428    0.2703    0.2975    0.0067
>>>>> >>>>
>>>>> >>>> And I just tried low1:
>>>>> >>>>
>>>>> >>>>     1.5470    0.2842    0.2995   33.8112    0.6661    0.5224
>>>>> >>>>
>>>>> >>>> Weird! Column 4 is for Sparse linear algebra...
>>>>> >>>>
>>>>> >>>> Maybe the issue is with R2014b? R2014a isn't still available on
>>>>> any
>>>>> of
>>>>> >>>> the autonlab servers for comparison is it?
>>>>> >>>>
>>>>> >>>> Seth
>>>>> >>>>
>>>>> >>>> On Mon, Jan 12, 2015 at 8:35 PM,  <predragp at andrew.cmu.edu>
>>>>> wrote:
>>>>> >>>>> Oh and I forgot to say. If a single core on my server is slower
>>>>> than
>>>>> >>>>> a
>>>>> >>>>> single core on your laptop then I would expect your LAPTOP to
>>>>> execute
>>>>> >>>>> code
>>>>> >>>>> faster. The catch is that server can do massive parallel
>>>>> processing
>>>>> >>>>> and
>>>>> >>>>> that what MATLAB is very good for.
>>>>> >>>>>
>>>>> >>>>> Predrag
>>>>> >>>>>
>>>>> >>>>>
>>>>> >>>>>
>>>>> >>>>>
>>>>> >>>
>>>>> >>
>>>>> >>
>>>>> >
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>






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