[petsc-dev] Kokkos/Crusher perforance

[Junchao Zhang]

On Mon, Jan 24, 2022 at 12:55 PM Mark Adams <mfadams at lbl.gov> wrote:

>
>
> On Mon, Jan 24, 2022 at 1:38 PM Junchao Zhang <junchao.zhang at gmail.com>
> wrote:
>
>> Mark, I think you can benchmark individual vector operations, and once we
>> get reasonable profiling results, we can move to solvers etc.
>>
>
> Can you suggest a code to run or are you suggesting making a vector
> benchmark code?
>
Make a vector benchmark code, testing vector operations that would be used
in your solver.
Also, we can run MatMult() to see if the profiling result is reasonable.
Only once we get some solid results on basic operations, it is useful to
run big codes.


>
>
>>
>> --Junchao Zhang
>>
>>
>> On Mon, Jan 24, 2022 at 12:09 PM Mark Adams <mfadams at lbl.gov> wrote:
>>
>>>
>>>
>>> On Mon, Jan 24, 2022 at 12:44 PM Barry Smith <bsmith at petsc.dev> wrote:
>>>
>>>>
>>>>   Here except for VecNorm the GPU is used effectively in that most of
>>>> the time is time is spent doing real work on the GPU
>>>>
>>>> VecNorm              402 1.0 4.4100e-01 6.1 1.69e+09 1.0 0.0e+00
>>>> 0.0e+00 4.0e+02  0  1  0  0 20   9  1  0  0 33 30230   225393      0
>>>> 0.00e+00    0 0.00e+00 100
>>>>
>>>> Even the dots are very effective, only the VecNorm flop rate over the
>>>> full time is much much lower than the vecdot. Which is somehow due to the
>>>> use of the GPU or CPU MPI in the allreduce?
>>>>
>>>
>>> The VecNorm GPU rate is relatively high on Crusher and the CPU rate is
>>> about the same as the other vec ops. I don't know what to make of that.
>>>
>>> But Crusher is clearly not crushing it.
>>>
>>> Junchao: Perhaps we should ask Kokkos if they have any experience with
>>> Crusher that they can share. They could very well find some low level magic.
>>>
>>>
>>>
>>>>
>>>>
>>>> On Jan 24, 2022, at 12:14 PM, Mark Adams <mfadams at lbl.gov> wrote:
>>>>
>>>>
>>>>
>>>>> Mark, can we compare with Spock?
>>>>>
>>>>
>>>>  Looks much better. This puts two processes/GPU because there are only
>>>> 4.
>>>> <jac_out_001_kokkos_Spock_6_1_notpl.txt>
>>>>
>>>>
>>>>
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