[petsc-users] Memory usage scaling with number of processors

[Matthew Knepley]

Also, you could run with

  -mat_view ::ascii_info_detail

and send the output for both cases. The storage of matrix values is not
redundant, so something else is
going on. First, what communicator do you use for the matrix, and what
partitioning?

  Thanks,

     Matt

On Mon, Jul 22, 2024 at 10:27 PM Barry Smith <bsmith at petsc.dev> wrote:

> Send the code. On Jul 22, 2024, at 9: 18 PM, Matthew Thomas via
> petsc-users <petsc-users@ mcs. anl. gov> wrote: ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍
> ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍
> ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍
> ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍
> ZjQcmQRYFpfptBannerStart
> This Message Is From an External Sender
> This message came from outside your organization.
>
> ZjQcmQRYFpfptBannerEnd
>
>   Send the code.
>
> On Jul 22, 2024, at 9:18 PM, Matthew Thomas via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
> This Message Is From an External Sender
> This message came from outside your organization.
>
> Hello,
>
> I am using petsc and slepc to solve an eigenvalue problem for sparse matrices. When I run my code with double the number of processors, the memory usage also doubles.
>
> I am able to reproduce this behaviour with ex1 of slepc’s hands on exercises.
>
> The issue is occurring with petsc not with slepc as this still occurs when I remove the solve step and just create and assemble the petsc matrix.
>
> With n=100000, this uses ~1Gb with 8 processors, but ~5Gb with 40 processors.
>
> This was done with petsc 3.21.3, on linux compiled with Intel using Intel-MPI
>
> Is this the expected behaviour? If not, how can I bug fix this?
>
>
> Thanks,
> Matt
>
>
>

-- 
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

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