[petsc-dev] PETSc GPU example

[Matthew Knepley]

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

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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