[petsc-users] Bad memory scaling with PETSc 3.10

[Mark Adams]

This looks like it might be noisy data. I'd make sure you run each size on
the same set of nodes and you might run each job twice (A,B,A,B) in a job
script.

On Wed, Apr 10, 2019 at 8:12 AM Myriam Peyrounette via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Here is the time weak scaling from the same study. The 3.10.2 version
> seems to be much more stable with regard to the execution time. But not
> necessarily faster for "large scale" simulations (problem size = 1e8).
>
> I didn't use -mat_freeintermediatedatastructures. I tested it this morning
> and the solver diverges when using this option (KSPReason -3).
>
> Myriam
>
> Le 04/09/19 à 17:23, Zhang, Hong a écrit :
>
> Myriam,
> Do you have 'execution time scalability' plot? Did you use
> '-mat_freeintermediatedatastructures' for PETSc 3.10.2?
> We made several computing optimizations on MatPtAP(), which might trade
> memory for speed. It would be helpful to see a complete comparison.
> Hong
>
> On Tue, Apr 9, 2019 at 7:43 AM Myriam Peyrounette via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Hi,
>>
>> in my first mail, I provided a memory scaling concerning the PETSc
>> example #42. You'll find attached the main files used (one for PETSc
>> 3.6.4, one for PETSc 3.10.2), and the corresponding memory scaling.
>>
>> In the main files, I modified the solver/preconditioner, so that it
>> corresponds to my problem. You'll find the modifications by searching
>> the keyword "TopBridge". In particular, I use GAMG.
>>
>> Note that the example is about solving Stokes equation, so using GAMG
>> may not be adapted. However, the memory gap appears and that's the
>> point. No matter if the results are correct.
>>
>> Are these scripts useful for you? Let me know.
>>
>> Thanks,
>>
>> Myriam
>>
>>
>> Le 04/04/19 à 00:09, Jed Brown a écrit :
>> > Myriam Peyrounette via petsc-users <petsc-users at mcs.anl.gov> writes:
>> >
>> >> Hi all,
>> >>
>> >> for your information, you'll find attached the comparison of the weak
>> >> memory scalings when using :
>> >>
>> >> - PETSc 3.6.4 (reference)
>> >> - PETSc 3.10.4 without specific options
>> >> - PETSc 3.10.4 with the three scalability options you mentionned
>> >>
>> >> Using the scalability options does improve the memory scaling. However,
>> >> the 3.6 version still has a better one...
>> > Yes, this still looks significant.  Is this an effect we can still
>> > reproduce with a PETSc example and/or using a memory profiler (such as
>> > massif or gperftools)?  I think it's important for us to narrow down
>> > what causes this difference (looks like almost 2x on your 1e8 problem
>> > size) so we can fix.
>>
>> --
>> Myriam Peyrounette
>> CNRS/IDRIS - HLST
>> --
>>
>>
> --
> Myriam Peyrounette
> CNRS/IDRIS - HLST
> --
>
>
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