[petsc-users] Questions about memory usage in Petsc

[neil liu]

Dear users and developers,

I am recently running a large system from Nedelec element, 14 million dofs
(complex number).
A little confused about the memory there. Then I tried a small system
(34,000 dofs) to see the memory usage. It was solved with MUMPS with 1
rank.
Then I used  PetscMemoryGetCurrentUsage() to show the memory used there.
The pseudocode is
PetscMemoryGetCurrentUsage (*Memory 1:* 64.237M)
KSPset
KSPsolve  (INFOG(18) (size of all MUMPS internal data allocated during
factorization: value on the most memory consuming processor): *Memory 2:*  408
MB)
PetscMemoryGetCurrentUsage (*Memory 3: *54.307M)

[0] Maximum memory PetscMalloc()ed 49.45MB maximum size of entire process
424MB (*Memory 4:* 54.307M)
The following is my understanding, please correct me if I am wrong,
It seems the difference between Memory 1 and 3 is approximately the size of
30 Krylov vectors (complex).
It seems Memory 4 is not the summation of Memory 2 and 3; but on the same
order of magnitude. It is a little confusing here.

Thanks,
Xiaodong
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