[petsc-users] question about PetscLogEvents

[Jed Brown]

Mohammad Mirzadeh <mirzadeh at gmail.com> writes:

> I'm gathering statistics for scaling analysis of my code and I'm making use
> of PetscLogEvent objects. Some of events I'm trying to log have run-times
> of few (1-5) seconds. Should I worry about any additional overheads?
>
> In general how long should an event be to not worry about overheads?

When you run with -log_summary, you'll see a line like this:

  Average time to get PetscTime(): 9.53674e-08

This value of around 100 nanoseconds is typical, and is about the same
as a full cache miss.  You generally want your events to take
significantly longer than this, say at least a microsecond.
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