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Subject: [OMPI users] opal_timer_linux_open() setting inexact floating point exception
From: Orion Poplawski (orion_at_[hidden])
Date: 2012-06-14 13:21:44


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