[petsc-dev] PETSc GPU example

[Fande Kong]

On Mon, Dec 6, 2021 at 5:59 PM Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Dec 6, 2021 at 7:54 PM Fande Kong <fdkong.jd at gmail.com> wrote:
>
>> Thanks, Matt,
>>
>> Sorry, I still have more questions on this example. How to refine mesh to
>> make the problem larger?
>>
>> I tried the following options, and none of them worked. I might do
>> something wrong.
>>
>> -ex56_dm_refine 9
>>
>> and
>>
>> -dm_refine 4
>>
>
> The mesh handling in this example does not conform to the others, but it
> appears that
>
>   -ex56_dm_refine <k>
>
> should take effect at
>
>
> https://gitlab.com/petsc/petsc/-/blob/main/src/snes/tutorials/ex56.c#L381
>
>
I was puzzled about this because DMSetFromOptions does not seem to trigger
-ex56_dm_refine.

I did a search, and could not find where we call " -ex56_dm_refine" in
PETSc.

I got the same result by running the following two combinations:

1) ./ex56  -log_view  -snes_view  -max_conv_its 3 -ex56_dm_refine 10

2) ./ex56  -log_view  -snes_view  -max_conv_its 3 -ex56_dm_refine 0

Thanks,

Fande


unless you are setting max_conv_its to 0 somehow.
>
>   Thanks,
>
>      Matt
>
>
>> Thanks,
>>
>> Fande
>>
>> On Mon, Dec 6, 2021 at 5:04 PM Matthew Knepley <knepley at gmail.com> wrote:
>>
>>> On Mon, Dec 6, 2021 at 7:02 PM Fande Kong <fdkong.jd at gmail.com> wrote:
>>>
>>>> Thanks, Matt
>>>>
>>>> On Mon, Dec 6, 2021 at 4:47 PM Matthew Knepley <knepley at gmail.com>
>>>> wrote:
>>>>
>>>>> On Mon, Dec 6, 2021 at 6:40 PM Fande Kong <fdkong.jd at gmail.com> wrote:
>>>>>
>>>>>> Dear PETSc team,
>>>>>>
>>>>>> I am interested in a careful evaluation of PETSc GPU performance in
>>>>>> our INL cluster.
>>>>>>
>>>>>> Any example in PETSc that can show GPU speedup with solving a
>>>>>> nonlinear equation?
>>>>>>
>>>>>> I talked to Junchao; he suggested that I try SNES/tutorial/ex56. I
>>>>>> tried that, but I could not find any speedup using the GPU. I could attach
>>>>>> some results of "log_view" later if we would like to see that.
>>>>>>
>>>>>
>>>>> We should note that you will only see speedup in the solver, so that
>>>>> problem has to be pretty large. I believe Mark has good results with it.
>>>>> The assembly is still all on the CPU. I am working on this over break,
>>>>> and hope to have a CEED version of it by the new year.
>>>>>
>>>>
>>>> Are both function and matrix assmelies on CPU? Or just the matrix
>>>> assembly?
>>>>
>>>
>>> There is no GPU assembly right now.
>>>
>>>   Matt
>>>
>>>
>>>> OK, I will try to check the solver part
>>>>
>>>> Thanks, again
>>>>
>>>> Fande
>>>>
>>>>
>>>>
>>>>>
>>>>>   Thanks,
>>>>>
>>>>>      Matt
>>>>>
>>>>>
>>>>>> Appreciate any instructions/comments about running a simple PETSc GPU
>>>>>> example to get a speedup.
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Fande
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> What most experimenters take for granted before they begin their
>>>>> experiments is infinitely more interesting than any results to which their
>>>>> experiments lead.
>>>>> -- Norbert Wiener
>>>>>
>>>>> https://www.cse.buffalo.edu/~knepley/
>>>>> <http://www.cse.buffalo.edu/~knepley/>
>>>>>
>>>>
>>>
>>> --
>>> What most experimenters take for granted before they begin their
>>> experiments is infinitely more interesting than any results to which their
>>> experiments lead.
>>> -- Norbert Wiener
>>>
>>> https://www.cse.buffalo.edu/~knepley/
>>> <http://www.cse.buffalo.edu/~knepley/>
>>>
>>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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