open TELEMAC-MASCARET The mathematically superior suite of solvers

Hey,

I use Telemac to make models with a lot of mesh and with slow flood
My biggest model contain around 1000000 meshes and the real time is equal to 5 days
The computation time is greater than twice the real-time
My question is which type of components and configuration can improved my computation time : processor, biprocessor, number of cores, RAM, OS,...

Thank for your help

Regards

Marine

Wow! big question...
When you wrote 1 000 000 mesh you mean elements or nodes?
When you wrote twice the real-time, could you give more information on your configuration...

Improving the computation time coulb be done by using recent processors on 64 bits architectures. The parallelism is also an efficient solution if you could access to a cluster or a multi-processor machine.

You should know that some options are time consuming and some other allow fastest computation... But that could have an effect on the results

At least, it's also possible to work on the mesh to allow larger time step and by consequence reduce the computation time ...

Regards

Hello,

Flood events have been done with Telemac-2D on 2000 square kms domains, during 2 months, so it would be worth looking also at the numerical options, maybe some optimisation is possible.

To know how efficient is your computer you can test in version 6.2 the Malpasset case. On a desktop HP Z600 Linux 64 bits with 8 processors, it takes 4 s (speed-up 5 to 6). Other deskstop machines now take 3 s, and HP Z620 has 16 cores, it should be even faster.

With very large domains like yours, the speed-up due to parallelism should be very good even with a large number of processors.

With best regards,

Jean-Michel Hervouet

I agree with Jean-Marie,

Recently, I've simulated a dam break model with concomitant floods from secondary reachs downstream (domain 36000 km², 24h simulation) on a 4 processors (8 cores) workstation. It took me less than 4 hours. I can tell you that the mesh was huge. I based my case file on the malpasset one with some minor modifications.

Aissa

Thank a lot for your replies

I know is a very general question. I’m thinking about buying a new computer to make simulation in 64 bits
I have 1 000 000 nodes in my biggest model.

My actual configuration is:
Widows 7 32 bits
Intel core i7 3.33GHz
RAM 6Go
6 cores HT
I join my steering file

We use V6P1 version of Télémac on 8 cores with variable time step. We have a lot meshes because it is flood model in dense urban area
So we modelize the street with edge length equal to 1. The first work for me is necessary to minimize the number of meshes.

I made some test on 64 bits, I don’t understand why Télémac use only 3Go of RAM? It is my configuration or the configuration of Télémac?

Another question it is better to have bi-processor, several processors or a lot of cores?

Is it possible to make cluster simulation with Télémac when we use MPICH2? If it is possible, how can we do?

Best Regards
Marine

Hi
In the street, the flow is along the street so this is the length along the street which is important for the time step.
Using the varaible time step could be dangerous if you have only one small element which could constraint all the model...
Telemac don't require a lot of memory to run, in 32 or 64 bits so for me the 3Go is not really a problem.
Your computer looks like efficient (core i7). The only advise for me on this point is to move to a full 64 bits version (Windows, compiler ...)
About your steering file, if you use the wave equation, Jean-Michel will tell you to choose solver 1.
About processor, it's allways better to have independant processor because the memory isn't share between them. The HT could generate memory share and them some slowing due to memory access.

The cluster computation is possible with MPICH2. You should compile Parallel version of Telemac and well configure the system to declare the different nodes. This could require some habits in the telemac configuration and a little informatic knowing... It seems to me there is a point on this subject in the training of the next Telemac User's club ...

Regards

Hey,

Do you know if there is a tutorial to use MPICH2 in cluster with Télémac?
Do you need to install Télémac in each computer used in cluster?
Do you know if somebody had already done cluster computation on Windows?
I know there is a forum of MPICH but it is obscure and no really adapted for Télémac use ... so I didn't find my answer
Unfortunately, I can’t be in the Telemac User's club ...

Regards

Marine

Another thing, where can we find the Malpasset case for version 6.2?
And when you said "HP Z600 Linux 64 bits with 8 processors" it is 8 cores or 8 processors ? If it is processors, how many cores have each processors?

Thank for your help

Regards

Marine

Hello Marine,

You can find the Malpasset test-case in version 6.2 in
svn.opentelemac.org/svn/opentelemac/vali..._v6p2/201_malpasset/

I suppose that my colleague Jean-Michel means a 2 quad-core processors when he talks about 8 processors.

Regards,

Chi-Tuan

OK thank you !

Regards

Marine