[petsc-users] strong-scaling vs weak-scaling

[Jed Brown]

Mark Adams <mfadams at lbl.gov> writes:

>>
>>
>> Anyway, what I really wanted to say is, it's good to know that these
>> "dynamic range/performance spectrum/static scaling" plots are designed to
>> go past the sweet spots. I also agree that it would be interesting to see a
>> time vs dofs*iterations/time plot. Would it then also be useful to look at
>> the step to setting up the preconditioner?
>>
>>
> Yes, I generally split up timing between "mesh setup" (symbolic
> factorization of LU), "matrix setup" (eg, factorizations), and solve time.
> The degree of amortization that you get for the two setup phases depends on
> your problem and so it is useful to separate them.

Right, there is nothing wrong with splitting up the phases, but if you
never show a spectrum for the total, then I will be suspicious.  And if
you only show "per iteration" instead of for a complete solve, then I
will assume that you're only doing that because convergence is unusably
slow.
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