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Subject: Re: [OMPI users] opal_timer_linux_open() setting inexact floating point exception
From: Ralph Castain (rhc_at_[hidden])
Date: 2012-06-14 13:32:33


Huh - weird. I've never seen that warning appear. What system was this on?

The code you flagged gets called exactly once, so overhead isn't an issue. Just puzzling why it would now suddenly appear after it has been there for years.

On Jun 14, 2012, at 11:21 AM, Orion Poplawski wrote:

> While trying to debug some other stuff, I discovered that opal_timer_linux_open() ends up setting the inexact floating point exception here:
>
> /* numer is in MHz - convert to Hz and make an integer */
> opal_timer_linux_freq = (opal_timer_t) cpu_f * 1000000;
>
> I'm not sure if this is anything we should care about or not, but when linked to the pgf runtime you end up with the following warning output:
>
> Warning: ieee_inexact is signaling
>
> I tried to see if I could do the conversion without triggering this to no avail. One could avoid changing the state with:
>
> #include <fenv.h>
>
> fecxept_t feflags
> fegetexceptflag(&feflags, FE_INEXACT);
> /* numer is in MHz - convert to Hz and make an integer */
> opal_timer_linux_freq = (opal_timer_t) cpu_f * 1000000;
> fesetexceptflag(&feflags, FE_INEXACT);
>
> But I'm not sure this is worth the overhead. Not sure how often this code is called.
>
> - Orion
>
> --
> Orion Poplawski
> Technical Manager 303-415-9701 x222
> NWRA, Boulder Office FAX: 303-415-9702
> 3380 Mitchell Lane orion_at_[hidden]
> Boulder, CO 80301 http://www.nwra.com
>
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