Messages in this thread | | | Date | Thu, 18 Nov 2010 23:39:48 +0300 | From | Cyrill Gorcunov <> | Subject | Re: [V2 PATCH 0/6] x86, NMI: give NMI handler a face-lift |
| |
On Thu, Nov 18, 2010 at 11:28:50PM +0300, Cyrill Gorcunov wrote: > On Thu, Nov 18, 2010 at 03:08:07PM -0500, Don Zickus wrote: > > On Thu, Nov 18, 2010 at 01:51:44PM -0600, Jason Wessel wrote: > > > > So the problem is when the nmi watchdog is enabled, the perf event is > > > > 'active' and thus tries to read the counter value. Because it is always > > > > zero, perf just assumes the counter overflowed and the NMI is his. > > > > > > > > Not sure how to fix it yet, other than include the logic that detects we > > > > are on a guest and disable perf?? > > > > > > > > > > > > > > I highly doubt we want to disable perf. I would rather use the source > > > and fix the nmi emulation in KVM/Qemu after we hear back the results > > > > Well I think Peter does not have a positive opinion about emulating perf > > inside a guest. Nor are the KVM folks having much success in doing so. > > > > Just to clarify, perf counter emulation is _not_ implemented in kvm. > > Therefore disabling perf in the guest makes sense until someone gets > > around to actually writing the emulation code for perf in a guest. :-) > > > > Cheers, > > Don > > Don, Robert, > > I still have suspicious on ours 'pending' nmi handler. Look what I mean -- > (keep in mind that p4 has a a way more counters than others). >
To be precise -- it seems this scenario may force the back-to-back nmi handler to eat unknown nmi.
Cyrill
| |