[GAP Forum] A question about ParGAP

[Alexander Konovalov]

Dear Sara,

> On 5 Jan 2016, at 10:50, Sara Yaftian <sara.yaftian at gmail.com> wrote:
> 
> Dear Forum
> 
> I have a question about ParGAP.
> I installed parGAP by the following command
> 
> cd pargap
> ./configure
> make
> 
> and then I need mpi and I installed mpi.
> Finally I paralleled a GAP program on Linux (Ubuntu 14.04 LTS) by the
> following command:
> 
> mpiexe -np 5 ./pargap.sh

Thank you for your question, and Happy New Year to you too! The above
steps seem to be correct. The rest depends on what "myprogram.txt" is
doing - it is quite common that when one tries to parallelise the code
then the first version of the parallel code runs slower than the 
sequential one.

Also, the phrase "I paralleled a GAP program" sounds a bit ambiguous, so
just in case: what 

mpiexe -np 5 ./pargap.sh

command is doing is that it starts several copies of GAP. One of them is
called 'master', and it provides the GAP command line interface and 
communicates with all the others, called 'slaves'. If you will call 

Read("myprogram.txt");

but the code there does not use any master-slave communication, it will
just perform the calculation on the master.

Best wishes
Alexander








> 
> when GAP run then I typed Read("myprogram.txt");
> 
> I am not sure my commands are correct or not because my laptop use 5 of CPU
> but the speed of my program has not changed. Would you please help me?
> 
> I wish you have a very happy New Year 2016.
> 
> Best regards
> Sara