[petsc-users] Investigate parallel code to improve parallelism

[TAY wee-beng]

On 26/2/2016 11:32 PM, Barry Smith wrote:
>> On Feb 26, 2016, at 9:28 AM, TAY wee-beng <zonexo at gmail.com> wrote:
>>
>> Hi,
>>
>> I have got a 3D code. When I ran with 48 procs and 11 million cells, it runs for 83 min. When I ran with 96 procs and 22 million cells, it ran for 99 min.
>     This is actually pretty good!
But if I'm not wrong, if I increase the no. of cells, the parallelism 
will keep on decreasing. I hope it scales up to maybe 300 - 400 procs.
>> So it's not that parallel. I want to find out which part of the code I need to improve. Also if PETsc and hypre is working well in parallel. What's the best way to do it?
>    Run both with -log_summary and send the output for each case. This will show where the time is being spent and which parts are scaling less well.
>
>     Barry
That's only for the PETSc part, right? So for other parts of the code, 
including hypre part, I will not be able to find out. If so, what can I 
use to check these parts?
>> I thought of doing profiling but if the code is optimized, I wonder if it still works well.
>>
>> -- 
>> Thank you.
>>
>> Yours sincerely,
>>
>> TAY wee-beng
>>