Improving code performance with EXPLICIT_VECTORIZATION

From: Leonard Romano <>
Date: Mon, 5 Jul 2021 11:27:27 +0200

Dear gadget-list members,

I would like to ask about your experiences with EXPLICIT_VECTORIZATION.
I am running cosmological hydrodynamics simulations on Intel
Xeon(E5-2699A v4) nodes. I was wondering if I could speed up my
simulations with EXPLICIT_VECTORIZATION so I set up two identical runs
-- one with and one without EXPLICIT_VECTORIZATION -- in order to see
which one is faster.
The results indicated that both performed equally well, i.e. they took
approximately equally long to perform the computation.
Now I am wondering if my compiler already implicitly vectorizes the
loops (I am using icpc (ICC) 17.0.3 and OpenMPI 2.0.0 with the compiler
flags -O3 -march=core-avx2 -Wall -Wno-format-security).
It would be interesting to see on which machines one can actually expect
an improvement with this option, so please share your experiences in
this thread!

Best regards,

Leonard Romano, B.Sc.(レオナルド・ロマノ)
Physics Department
Technical University of Munich (TUM), Germany
Theoretical Astrophysics Group
Department of Earth and Space Science
Graduate School of Science, Osaka University, Japan
he / him / his
Received on 2021-07-05 11:27:32

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