[petsc-users] Scalability

[Matthew Knepley]

On Thu, Feb 12, 2026 at 6:48 AM SCOTTO Alexandre via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Dear PETSc community,
>
>
>
> I have conducted a quick strong scalability-like test on direct and
> adjoint matrix-vector product with a 25,000 x 25,000 sparse matrix,
> distributed over 2, 4, …, 32 and 64 processes and the results I obtained
> were not so great.
>
> I am not very confident in my setup, so a as a matter of reference, is
> there any available results on weak and strong scalability of PETSc.Mat
> mult() and multTranspose() operations?
>

1. This behavior depends on available bandwidth, not on cores. Do you know
the bandwidth for your configurations?

2. Strong scaling depends heavily on matrix sparsity. If inevitably
declines, but slower with more work to do.

3. We published a paper on performance recently:
https://urldefense.us/v3/__https://www.sciencedirect.com/science/article/abs/pii/S016781912100079X__;!!G_uCfscf7eWS!Zr5jUpk1srGDF2h9mXmw_GIn1OFZ2g3APzC0JHZREcxRzzy-2Oz2yyBWtzSI6F21kV4W_ubmc7A0NIIoVXnb$ 

  Thanks,

      Matt

>
>
> Best regards,
>
> Alexandre.
>


-- 
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

https://urldefense.us/v3/__https://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!Zr5jUpk1srGDF2h9mXmw_GIn1OFZ2g3APzC0JHZREcxRzzy-2Oz2yyBWtzSI6F21kV4W_ubmc7A0NPzkrito$  <https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!Zr5jUpk1srGDF2h9mXmw_GIn1OFZ2g3APzC0JHZREcxRzzy-2Oz2yyBWtzSI6F21kV4W_ubmc7A0NEclfLI_$ >
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