[Scip] Performance of Nehalem machine

[Thorsten Koch]

Dear Anthony,.

Nehalem is a difficult animal. Maybe you can try to switch off
Hyperthreading and possibly TurboBoost. This would make is at
least somewhat predictable.

We have similar machines, could you provide us the instance?
Then we could have a look.

Best regards,
Thorsten

Am 20.04.2010 18:54, schrieb Anthony Presley:
> Hi all!
> 
> I've tried solving an MPS problem (about 24MB in size), with 4011
> variables and 65108 constraints.
> 
> In trying to benchmark scip, I installed scip on to two servers, along
> with CLP (from subversion).
> 
> One machine has these characteristics: (machine1)
> 	(2) Xeon 5570 Nehalem CPU's @ 2.93Ghz
> 	24GB of RAM
> 
> The other has these: (machine2)
> 	(1) Xeon E5410 @ 2.33Ghz
> 	8GB of RAM
> 
> Neither machine is doing anything other than running scip (and whatever
> background processing the kernel does).
> 
> However, in this case, when getting to say, a gap of 4724.87%, machine1
> looks like this:
> 
>  time | node  | left  |LP iter| mem |mdpt |frac |vars |cons |ccons|cols
> |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap   
> t 0.8s|     1 |     0 |     0 |  60M|   0 |   - |2866 |  46k|  46k|   0
> |   0 |   0 |   0 |   0 |      --      | 1.681391e+07 |    Inf 
>  42.9s|     1 |     0 | 25711 |  82M|   0 | 353 |2866 |  46k|  46k|2866
> |  46k|   0 |   0 |   0 | 3.481961e+05 | 1.681391e+07 |4728.86%
> b43.3s|     1 |     0 | 26093 |  82M|   0 |   - |2866 |  46k|  46k|2866
> |  46k|   0 |   0 |   0 | 3.481961e+05 | 1.680000e+07 |4724.87%
> 
> And machine2 (to get to the same gap) looks like this:
> 
>  time | node  | left  |LP iter| mem |mdpt |frac |vars |cons |ccons|cols
> |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap   
> t 0.7s|     1 |     0 |     0 |  60M|   0 |   - |2866 |  46k|  46k|   0
> |   0 |   0 |   0 |   0 |      --      | 1.681391e+07 |    Inf 
>  32.5s|     1 |     0 | 25711 |  82M|   0 | 353 |2866 |  46k|  46k|2866
> |  46k|   0 |   0 |   0 | 3.481961e+05 | 1.681391e+07 |4728.86%
> b32.8s|     1 |     0 | 26093 |  82M|   0 |   - |2866 |  46k|  46k|2866
> |  46k|   0 |   0 |   0 | 3.481961e+05 | 1.680000e+07 |4724.87%
> 
> 
> More specifically, the older, slower, processor solves (up to this
> point) almost 10 seconds faster.
> 
> I was expecting the opposite, out of a processor that is significantly
> more expensive.
> 
> Any ideas what's going on?
> 
> Both scip's were built using "make LPS=clp" and that's it.  Coin was
> built using "make".
> 
> Both boxes are running an up to date CentOS 5.4
> 
> Thanks!
> 
> 
> --
> Anthony
> 
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> Scip at zib.de
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-- 
The important thing is not to stop questioning.
Curiosity has its own reason for existing.          -- Albert Einstein
______________________________________________________________________
Dr. Thorsten Koch / Konrad-Zuse-Zentrum für Informationstechnik Berlin
www.zib.de/koch  /          Takustraße 7, 14195 Berlin-Dahlem, Germany
koch at zib.de     /                     Phone +49-30-84185-213, Fax -269
_______________/  DFG Research Center "Matheon"  http://www.matheon.de

Kooperativer Bibliotheksverbund Berlin Brandenburg  http://www.kobv.de
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