[petsc-users] [petsc-maint] Out of memory issue related to KSP.

[neil liu]

Thanks, mark.
I am using a sparse matrix from a second-oder vector basis FEM.
Will this sparse matrix still use a memory similar to a dense matrix?

Thanks,

Xiaodong


On Thu, Jul 18, 2024 at 6:00 PM Mark Adams <mfadams at lbl.gov> wrote:

> keep on the list.
>
>
>
>
> On Thu, Jul 18, 2024 at 5:06 PM neil liu <liufield at gmail.com> wrote:
>
>> The matrix size (complex) is 611,432 x 611,432.
>>
>
> A dense matrix of that size uses 3 terabytes to store 8*(611,432)^2 bytes.
>
> That is too big.
>
> Mark
>
>
>>
>> On Thu, Jul 18, 2024 at 4:58 PM Mark Adams <mfadams at lbl.gov> wrote:
>>
>>> How big is your matrix?
>>>
>>> On Thu, Jul 18, 2024 at 4:53 PM neil liu <liufield at gmail.com> wrote:
>>>
>>>> Dear Pestc team, I am trying to solve a complex linear system by Petsc
>>>> KSP. When I committed out this piece code, no errors came out. Will my
>>>> coding part affect ksp? I am using a direct solver, -pc_type LU.
>>>> PetscErrorCode ElementInfo: : solveLinearSystem(
>>>> ZjQcmQRYFpfptBannerStart
>>>> This Message Is From an External Sender
>>>> This message came from outside your organization.
>>>>
>>>> ZjQcmQRYFpfptBannerEnd
>>>> Dear Pestc team,
>>>>
>>>> I am trying to solve a complex linear system by Petsc KSP. When I
>>>> committed out this piece code, no errors came out. Will my coding part
>>>> affect ksp? I am using a direct solver, -pc_type LU.
>>>>
>>>> *PetscErrorCode ElementInfo::solveLinearSystem( ){ *
>>>> *PetscFunctionBegin; *
>>>> *KSP ksp; *
>>>> *KSPCreate(PETSC_COMM_WORLD, &ksp); *
>>>> *KSPSetType(ksp, KSPFGMRES); *
>>>> *KSPSetOperators(ksp, A, A); *
>>>> *KSPSetFromOptions(ksp); KSPSolve(ksp, b, x); *
>>>> *KSPDestroy(&ksp); *
>>>> *PetscFunctionReturn(PETSC_SUCCESS);*
>>>> * }*
>>>>
>>>> The output with -malloc_test and -malloc_view is attached. It shows the
>>>> following errors,
>>>> *Line 5  in the attached file *
>>>> [0]PETSC ERROR: --------------------- Error Message
>>>> --------------------------------------------------------------
>>>> [0]PETSC ERROR: Out of memory. This could be due to allocating
>>>> [0]PETSC ERROR: too large an object or bleeding by not properly
>>>> [0]PETSC ERROR: destroying unneeded objects.
>>>> [0] Maximum memory PetscMalloc()ed 19474398848 maximum size of entire
>>>> process 740352000 (*This only used 20% of my 64Gb memory .*)
>>>>  *Line 111 in the attached file*
>>>> [0]PETSC ERROR: Memory requested *18446744069642786816 * (*This is too
>>>> big.)*
>>>> [0]PETSC ERROR: See https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!frXqnQME2vz-dsM2ohLke9bFaRKeV5R43otxvpWSX4XCA-Ln5mVS2v7CQa2AXWb971drSs1ICwejJ00Vj-zFFw$ 
>>>> <https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ccZ34UzQhUBbNR8XsOs-FZm2yIW4bzLaYbGGphZTOcDpU5XZNTG_3iagHL_C6Z_e84LvVq04MoQToMzMYfU72jU$> for
>>>> trouble shooting.
>>>> [0]PETSC ERROR: Petsc Release Version 3.21.1, unknown
>>>> [0]PETSC ERROR: ./app on a arch-linux-c-debug named kirin.remcominc.com
>>>> <https://urldefense.us/v3/__http://kirin.remcominc.com/__;!!G_uCfscf7eWS!ccZ34UzQhUBbNR8XsOs-FZm2yIW4bzLaYbGGphZTOcDpU5XZNTG_3iagHL_C6Z_e84LvVq04MoQToMzM1VQhXLw$> by
>>>> xiaodong.liu Thu Jul 18 16:11:52 2024
>>>> [0]PETSC ERROR: Configure options --with-cc=gcc --with-fc=gfortran
>>>> --with-cxx=g++ --download-fblaslapack --download-mpich
>>>> --with-scalar-type=complex --download-triangle
>>>> [0]PETSC ERROR: #1 PetscMallocAlign() at /home/xiaod
>>>>
>>>
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