Beniamino Sciacca wrote:
> I don't know what is changed.. but I partially resolved the problem:
> is not an hardware problem (installing smp kernel it works).
> Now I've to use mpirun (before I didn't use it), and I don't succeed to
> tell the system to use both processors for only one process.
> In fact using "mpirun -c 2" it makes two processes, each for one cpu.
> I need to work with only one process, and before I succeeded in this.
> (with another computer dual core I'm able to do this.
> Thanks
Apologies, I'm not sure I understand what you're saying here.
You weren't using mpirun before? What were you using?
I don't see why two processes is bad - this to me is expected behavior,
as LAM/MPI will start one process per processor. Why do you need only
one process?
Another note.. does gromacs support some sort of native multithreaded
mode? This might perform better for you than using MPI would if you're
only using the one system.
Andrew
> Andrew Friedley ha scritto:
>
>>Beniamino Sciacca wrote:
>>
>>
>>>Hi community!
>>>I've a great problem:
>>>two months ago I installed LAM on my centrino duo, debian -kernel 2.6.
>>>Later I compiled gromacs enabling mpi, and everything was working well
>>>until four days ago.
>>>Now the simulation time is increased like if there is only one processor
>>>(it takes twice time than before).
>>>I don't understand why.
>>>I disinstalled and then reinstalled LAM and gromacs (LAM 7.1.2 (I
>>>compiled it on my own) + gromacs 3.3.1).
>>>Nothing has changed.
>>>I disinstalled linux and then reinstalled (debian kernel 2.6), and again
>>>LAM and gromacs: I've the same problem, like if one of the two cores
>>>doesn't work.
>>>I tried also to install gromacs NON mpi-enabled, and I've the same
>>>simulation time (respect to the enabled-mpi gromacs).
>>>In all these cases LAM seems to work (when I type lamboot LAM starts
>>>without problem).
>>>
>>>What's happened?
>>>How can I understand if it's a software problem or an hardware one?
>>>thank you very much for the reply!
>>>
>>
>>The first question I always ask is - what changed? You say it was
>>working properly up to some point, something must have happened at or
>>before that point.
>>
>>It's hard to tell based on the information you've given, but the first
>>thing I would do is make sure linux has both CPU's enabled, and that any
>>power management stuff isn't affecting your performance.
>>
>>Can you test any other applications, to see if this problem is specific
>>to LAM/gromacs?
>>
>>You might consider other support channels as well - I can't recommend a
>>good place for you off the top of my head, but LAM is not likely the
>>problem here.
>>
>>Andrew
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>
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