On Mon, 12 May 2008, luyi wrote:

> Now I write a DG programme on libmesh, when I use the FIRST or higher
> order basis, the first step is too slow,
> besides this everything is ok, I use XYZ basis and I check the code by
> perf_log, the time ratio is up to snuff.

The first time step (especially in a non-adaptive run) has some
overhead that later timesteps don't, but it's also possible you've
found a bug.  If we're not preallocating the sparse matrix with the
correct sparsity pattern, for example, PETSc might take quite a long
time on the first assembly.

Could you run your code for only one time step and check the perf_log
on that, to see what part of the code is taking too long?
---
Roy

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