[mpich-discuss] How to check core load

[Gus Correa]

Hi Basak

If you are in Linux, use the 'top' command to see the processes.
Top has options to show the cpu/core number also, see the top man page.

Note that you are oversubscribing the cores.
You have 12 physical cores, but you're launching 30 processes.
For cpi, which is very short, it may be OK, but for heavier programs
it is not really good to oversubscribe.

My two cents,
Gus Correa

Chandra Bhanu Basak wrote:
> Hi,
> 
> Thanks to Chan and Correa for their earlier replies that made me more 
> insightful.
> 
> I have compiled cpi.c (comes with MPICH2 example codes) using mpicc -o 
> cpi.c cpi
> 
> Ran it using two following commands -
> 
> mpiexec ./cpi
> 
> mpiexec -n 30 ./cpi
> 
> In first case it says "Process 0 on localhost.localdomain" and also 
> gives the value of PI and wall clock time (~ 10^-4 s).
> 
> In second case it says "Process 0 from localhost.localdomain"
> "Process 1 on localhost.localdomain"
> ...
> ...
> "Process 5 on localhost.localdomain"
> 
> etc. etc.
> 
> (since, localhost.localdomain is the machine's default name)
> 
> Since, my machine is a single box containing two processors (each having 
> 6 cores); how do I know that it uses all the cores? Also the associated 
> calculation time is so small it is difficult to catch the processes 
> using system monitor.
> 
> Is there any benchmarking program which will show how many cores were 
> used for the calculation.
> 
> Thanks in advance.
> 
> Basak
> 
> 
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