i am not sure, whether it is related to my problem with 2.6.28, but
running oprofile on kernel 2.6.29-rc4 (today's linus/master to be
exact), i do not get _any_ NMI:

tim@thinkpad:~$ sudo opcontrol -s
Using 2.6+ OProfile kernel interface.
Using log file /var/lib/oprofile/samples/oprofiled.log
Daemon started.
Profiler running.
tim@thinkpad:~$ cat /proc/interrupts |grep NMI
NMI:          0          0   Non-maskable interrupts
tim@thinkpad:~$ sudo opcontrol -d
tim@thinkpad:~$ cat /proc/interrupts |grep NMI
NMI:          0          0   Non-maskable interrupts

dmesg tells me:
oprofile: using NMI interrupt.

best, tim

-- 
tim@klingt.org
http://tim.klingt.org

When you open windows, bugs get in.