Dear PETSc users,
we use PETSc in our code.
Therefore, we have multiple PETSc compilations lying around, each
compiled differently,
e.g debug build using an Intel-compiler, optimized build for Intel-CPUs
using an Intel-compiler, optimized build for AMD-Rome-CPUs using an
Intel-compiler, several builds using GNU-compilers ...
Prior to compiling our code, we essentially set $PETSC_DIR and
$PETSC_ARCH to point to a suitable PETSc build.
When I compile such an optimized PETSc build aimed at Intel-CPUs and
using an Intel-compiler I do so with
COPTFLAGS="-axCOMMON-AVX512,CORE-AVX2,AVX ..."
to address all Intel processors available on our cluster.
However, I recently noticed that the PETSc compilation provided by our
HPC-administrators was compiled with -march=native.
Does that make sense? If so this implies that my optimization flags are
unnecessary, does it not?
I imagine that when using a PETSc previously compiled with march=native
and I compile that into my code on a CPU different from the one that has
been used when compiling PETSc, I end up without optimizations of PETSc.
Is that correct?
Best,
Bastian
