Parallel CPLEX - Global Thread Limit

[MatthiasW]

Hey everyone,

I'm using Parallel CPLEX to solve a very large scale MIP and since I'm
working on a machine with 4 CPUs, I set the global thread limit
parameter to 4.
However, when I look at the average utilization of my CPUs as
displayed on the Windows Ressourcemonitor, it is only at about 50%.
I'm working with a full academic license of AIMMS and one of my
colleagues believes that the reason for the low utilization of my CPUs
might be that for the academic version of AIMMS the number of threads
is artificially capped at 2.
Is this true and if so, is there any possibility to get the academic
version extended to more than 2 threads? I beliebe this would improve
my computation time significantly.


Thanks for your input, best
Matthias

[GdL]

Dear Matthias,

There is no artificial cap on your academic license on the number of
threads you can use when solving a model using CPLEX.
The Free AIMMS Academic License is a fully functional license.

Kind regards,
Gertjan de Lange
AIMMS

[Luis Pinto]

Using parallel threads to solve a model doesn't necessarily mean you will occupy all the threads at all times.
I know there are some synchronisations that occur during optimisation that could lead to periods of less CPU use.

How many threads can you computer actually use. Use said it has 4 CPU's but it may deal with more threads than that (ex: my PC has 2 cores, but 4 threads).
Check out you system configs.

Cheers,

Luis Pinto
www.unisoma.com.br

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[Sergio Bruno]

Maybe there is some hyper threading messing the stats.what happens if the limit is 8 threads?

[MatthiasW]

My machine has 4 CPUs, 2 cores and each physical core relates to 2
logical cores (at leat that's what I found via google..). So I should
be able to deal with up to 16 threads, I suppose... I'll try that.
Thanks for your comments!

On 28 Sep., 18:02, Sergio Bruno <svbbr...@gmail.com> wrote:
> Maybe there is some hyper threading messing the stats.what happens if the
> limit is 8 threads?
>