Re: [AMBER] Intel Compilers, SSE_TYPES, and auto CPU dispatch

From: Jason Swails <>
Date: Tue, 13 Jan 2015 12:38:38 -0500

On Tue, Jan 13, 2015 at 12:20 PM, Novosielski, Ryan <
> wrote:

> Wouldn't there be performance tradeoffs there? I'd think that at least
> supporting 4.1, in my case, would result in faster execution.

‚ÄčI thought I remembered somebody (Brent?) working on this very problem --
i.e., that SSE_TYPES is basically ignored by configure. I'm not sure what
came of it, but I was under the impression that he had gotten pretty far
with it. If he sees this and easily recalls what he's done, perhaps
(hopefully? :) he might chime in here.

I think the main problem here is that Amber uses the "-xHost" flag, which I
think activates all optimizations for the instruction set on the host
processor. This obviously causes problems on machines where the head node
supports more advanced vector instructions than the compute nodes, which
seems to be what's happening here.

Since I am under the impression that setting the SSE_TYPES variable does
*not* currently work for configure, I think your best bet might be to
backup configure2 inside $AMBERHOME/AmberTools/src and change "-xHost" to
the Intel compiler flags corresponding to the SSE instructions you
specifically want to enable (I'm not sure what those happen to be off the
top of my head).

Hopefully that helps you get somewhere...

Good luck!

Jason M. Swails
Rutgers University
Postdoctoral Researcher
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Received on Tue Jan 13 2015 - 10:00:02 PST
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