Re: [PATCH 1/2] Always probe the NMI watchdog

[Mikael Pettersson]

On Tue, 26 Jun 2007 02:57:55 -0700, Mikael Pettersson wrote:
> > Keeping parts of the PMU HW permanently reserved whether or not
> > the watchdog is enabled would be a BUG.
> > 
> True. But the upside is that you guarantee the activation of the NMI
> watchdog will always succeed which may be a valuable property given the
> goal of the NMI watchdog. Otherwise, if Oprofile or perfmon are active,
> the NMI will fail to grab a single counter.

That relates more to policy than mechanism. I for one don't
consider the watchdog "sacred".

I think it's entirely reasonable that if the watchdog is disabled
(echo 0 > /proc/sys/kernel/nmi_watchdog) in order to give the
_full_ PMU HW to something else, then that something else needs
to be disabled (or otherwise instructed to give up the HW) before
the watchdog can be reenabled. If you don't want to risk not
being able to restart the watchdog, don't disable it.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/