[ALPS-users] execution time of example/parapack/exchange

[Dominik Schildknecht]

Dear Synge,

thanks for your fast reply. I tried your suggestions, however without
success. I wrote a small script (which I appended, if you want to also
test it), which analyses time of execution in several attempts and does
some statistics on it.

It calls the command with 

mpirun -np N ./exchange --mpi --threads-per-clone N exchange.ip.in.xml

for N in 1 to 4. It seems that execution time is slightly increasing
with number of MPI cores, such that I assume that this comes from the
additional MPI overhead. However I see no speed-up in terms of parallel
execution of different replicas.

Did I miss something else?
Best,
Dominik

On 16.05.2017 17:02, Synge Todo wrote:
> Dear Dominik,
>
> The parapack scheduler supports parallel workers.
> You can run the exchange worker in parallel by using multiple threads or processes provided that
>
> 1. the parameters are given by XML files instead of the standard input, and
>     (running with standard input is for debugging or testing)
> 2. multiple threads are assigned to each worker by using -p (--threads-per-clone) option
>     (default is -p 1).
>
> Please try, e.g.,
>
> $ parameter2xml exchange.ip
> $ mpirun -np 4 ./exchange --mpi --threads-per-clone 4 exchange.ip.in.xml
>
> Best,
> Synge
>
>
>> From: Dominik Schildknecht <dominik.schildknecht at psi.ch>
>> Subject: [ALPS-users] execution time of example/parapack/exchange
>> Date: 16 May 2017 at 01:48:28 GMT-7
>> To: <comp-phys-alps-users at lists.phys.ethz.ch>
>> Reply-To: comp-phys-alps-users at lists.phys.ethz.ch
>>
>> Dear all,
>>
>> I was testing your example in example/parapack/exchange with the
>> exchange.ip modified to only test the ising case, however with more
>> sweeps, to test the time spent.
>>
>> I know that the parallel_exchange_worker gets called (visible via the
>> line "EXMC: number of replicas on each process = 2 2", which will only
>> be outputted by the parallel_exchange_worker). I would by this output
>> assume that different replicas get distributed over the cores,.
>>
>> The time spent in the simulation however stays the same irrespective of
>> the number of processes I provide to MPI or not even call the MPI
>> library at all.
>>
>> I call the function in the following way:
>>
>>    mpirun -np 2 ./exchange --mpi < exchange.ip
>>
>> resp.
>>
>>    ./exchange < exchange.ip
>>
>> Do I miss an important argument in the input file / command line
>> argument, that prevents the parallel execution of replicas?
>>
>> Best,
>> Dominik
>>
>> -- 
>> Paul Scherrer Institut
>> Dominik Schildknecht
>> PhD Student
>> WHGA/129
>> CH-5232 Villigen-PSI
>> Phone: +41 56 310 55 68
>>
>>
>>
>>
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>
>
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-- 
Paul Scherrer Institut
Dominik Schildknecht
PhD Student
WHGA/129
CH-5232 Villigen-PSI
Phone: +41 56 310 55 68

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