When I enter 'opcontrol --start' or 'opcontrol --start-daemon', I got a error message like this :

Error: counter 0 not available nmi_watchdog using this resource ? Try:
opcontrol --deinit
echo 0 > /proc/sys/kernel/nmi_watchdog

I did what it says but it doesn't work.
I've installed Oprofile by 'yum install oprofile'
and I've tried it in Xen-based kernel to profile in virtual machine environment.
Please help me.

Thank you.