On Mon, 25 Jun 2007 23:04:25 +0200, [email protected] wrote:
> > I think the tricky part is that we do want to reserve perfctr1 even
> > though the NMI watchdog is not active. This comes from the fact that
> > the NMI watchdog knows about only one counter and if it can't get that
> > one, it probably fails. By reserving it from the start, we ensure NMI
> > watchdog will work when eventually activated.
>
> Can you enable it later on at all? It failed for me when I tried,
> because it didn't know which hardware to use. Had to pass the kernel
> parameter to make the proc files do anything. Seems like it has to be
> enable at boot to work at all.
>
> And AFAICT we never unconditionally reserved a perfctr for the watchdog.
Yes you can dynamically enable/disable the NMI watchdog,
at least if you booted with it enabled.
> In 2.6.21 the nmi watchdog, if enabled, just reserved its perfctrs and
> everything else had to deal with it. Since the cleanup, the watchdog
> will release its perfctr when disabled, so another subsystem can grab
> it. But that also means that that other subsystem must release it again
> before you can reenable the watchdog.
Which is the obvious and correct way to handle a shared resource.
Keeping parts of the PMU HW permanently reserved whether or not
the watchdog is enabled would be a BUG.
/Mikael
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
