[Scip] Performance of Nehalem machine

[michael.winkler@zib.de]

Hi Anthony,

unfortunately, it's always possible that some instances could run longer
on even better processors.

It seems that the complete time difference appears to be the LP
solvingtime, so maybe it's an CLP issue.

Another possibility is, that you have one machine with a 32 bit and
another with a 64 bit system, which could also lead to such result. (Some
compiler flags are different for 64 and 32 bit code in the SCIP
makefiles.)

I hope that helps you a little, even if it's not your desired result.

Best regards, Michael


> 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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