[petsc-users] using intel mkl for optimized blas/lapack on amd nodes

[Junchao Zhang]

Hi, Chris,
  Could you check out this MR
https://urldefense.us/v3/__https://gitlab.com/petsc/petsc/-/merge_requests/9327__;!!G_uCfscf7eWS!ctF3nShH_6dTwbShHGEKUtwTmiwcG7QifVwCzUXYkhfzZUUbY2Qjzn9hPfKSa3jOWkC94o2dELHf38z0XsL4xh-DrwXl$  and test
the attached ex00.c in your environment to see if it makes a difference?

  On my machine, it helps a little, as the MKL version alway optimizes for
Zen.

  Thanks!
--Junchao Zhang


On Fri, Jun 5, 2026 at 2:07 AM Klaij, Christiaan <C.Klaij at marin.nl> wrote:

> If the users are supposed to know this and act on it, perhaps an entry in
> the FAQs to raise awareness? With instruction how to check if the user's
> computing center automatically applies the trick.
>
> Chris
>
> ________________________________________
> ​​​​
> dr. ir.  Christiaan  Klaij  |  senior researcher
> Research & Development  |  CFD Development
> T +31 317 49 33 44 <+31%20317%2049%2033%2044>  |  https://urldefense.us/v3/__http://www.marin.nl__;!!G_uCfscf7eWS!ctF3nShH_6dTwbShHGEKUtwTmiwcG7QifVwCzUXYkhfzZUUbY2Qjzn9hPfKSa3jOWkC94o2dELHf38z0XsL4xgaQGxNe$ 
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>
> From: Pierre Jolivet <pierre at joliv.et>
> Sent: Thursday, June 4, 2026 5:03 PM
> To: Junchao Zhang
> Cc: Richard Tran Mills; PETSc users list; Klaij, Christiaan
> Subject: Re: [petsc-users] using intel mkl for optimized blas/lapack on
> amd nodes
>
> You don't often get email from pierre at joliv.et. Learn why this is
> important<https://urldefense.us/v3/__https://aka.ms/LearnAboutSenderIdentification__;!!G_uCfscf7eWS!ctF3nShH_6dTwbShHGEKUtwTmiwcG7QifVwCzUXYkhfzZUUbY2Qjzn9hPfKSa3jOWkC94o2dELHf38z0XsL4xv4xA4yr$ >
> The libfakeintel.so<https://urldefense.us/v3/__http://libfakeintel.so__;!!G_uCfscf7eWS!ctF3nShH_6dTwbShHGEKUtwTmiwcG7QifVwCzUXYkhfzZUUbY2Qjzn9hPfKSa3jOWkC94o2dELHf38z0XsL4xpIBoj_E$ > trick is as old as I can
> remember and it is available in all computing centers I’m using.
> But it’s the duty of the users to preload it (again, on computing centers
> I have access to, module load’ing the MKL on AMD nodes automatically sets
> LD_PRELOAD).
>
> Thanks,
> Pierre
>
> On 4 Jun 2026, at 4:52 PM, Junchao Zhang <junchao.zhang at gmail.com> wrote:
>
> Richard, do you want to trick Intel?
>
> --Junchao Zhang
>
>
> On Thu, Jun 4, 2026 at 2:29 AM Klaij, Christiaan via petsc-users <
> petsc-users at mcs.anl.gov<mailto:petsc-users at mcs.anl.gov>> wrote:
> I came across this issue:
>
> https://urldefense.us/v3/__https://danieldk.eu/software/misc/intel-mkl-on-amd-zen__;!!G_uCfscf7eWS!ctF3nShH_6dTwbShHGEKUtwTmiwcG7QifVwCzUXYkhfzZUUbY2Qjzn9hPfKSa3jOWkC94o2dELHf38z0XsL4xlBmyDlt$ <
> https://urldefense.us/v3/__https://danieldk.eu/software/misc/intel-mkl-on-amd-zen__;!!G_uCfscf7eWS!fsSSG7b4cHz_fsk3H-3DI4kIopw4fIp1MW93aPTq10vZnZKOx1t7cEg2g4MbGyxZXr15OMM0jg0UU0q2p5ktYkQ$
> >
>
> We do configure petsc with the intel mkl for optimized
> blas/lapack using --with-blas-lapack-dir=${MKL_DIR}.
>
> How much would this issue affect the performance of petsc on amd
> nodes? Do you have the proposed workaround in place?
>
> Chris
> <image455803.png>
> ​​​​
> dr. ir. Christiaan Klaij | senior researcher
> Research & Development | CFD Development
> T +31 317 49 33 44<tel:+31%20317%2049%2033%2044> | https://urldefense.us/v3/__http://www.marin.nl__;!!G_uCfscf7eWS!ctF3nShH_6dTwbShHGEKUtwTmiwcG7QifVwCzUXYkhfzZUUbY2Qjzn9hPfKSa3jOWkC94o2dELHf38z0XsL4xgaQGxNe$ <
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