Re: [modeller_usage] Differences using Xeon vs Opteron systems
To: Robert Healey <>
Subject: Re: [modeller_usage] Differences using Xeon vs Opteron systems
From: Modeller Caretaker <>
Date: Tue, 15 Feb 2011 09:12:34 -0800
Cc:
On 2/14/11 5:20 PM, Robert Healey wrote:
Having the researchers run some more comparisons, I've found that the
modeller9v3-absoft gives consistent results across both CPU platforms
Yes, because it does not use any of the SSE functionality or any other
optimization that differs between platforms. We provide that binary for
systems that don't support SSE, such as FreeBSD's Linux layer.
As I said, it really makes no sense to rely on exact results, since the
accuracy of the force field is far less than machine precision. The
absoft binary is also noticeably slower.
They also tried them x86_64 RPM 9v8 and the results matched the 9v3
x86_64 RPM results on both platforms. We're switching to -absoft on all
systems now for consistency, but it would be nice if that was available
as a 64 bit build also.
You are of course welcome to do this if you want, but it is not a
supported use case. And we certainly have no plans to build additional
64-bit binaries, where lack of SSE functionality is not an issue (since
it is built into the x86_64 instruction set).