Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 2 Sep 2010 11:47:43 -0400 | From | Don Zickus <> | Subject | Re: [PATCH 4/4] [x86] perf: fix accidentally ack'ing a second event on intel perf counter |
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On Thu, Sep 02, 2010 at 04:39:02PM +0200, Stephane Eranian wrote: > Don, > > On Thu, Sep 2, 2010 at 4:19 PM, Don Zickus <dzickus@redhat.com> wrote: > > On Thu, Sep 02, 2010 at 10:13:19AM +0200, Stephane Eranian wrote: > >> Robert, > >> > >> Do you have the test program you used to test this? > >> I believe the NHM hack does not solve the problem, it > >> just makes it harder to appear. > > > > Could be. > > > >> > >> I suspect the real issue is that the GLOBAL_STATUS > >> bitmask cannot be trusted. I'd like to verify this. > >> > >> Has the problem appear only on Nehalem or also on > >> Westmere? > > > > I was able to duplicate on > > > > Intel(R) Core(TM) i5 CPU 650 @ 3.20GHz > > Intel(R) Xeon(R) CPU X5560 @ 2.80GHz > > > I managed to reproduce on core i7 860 (without patch4). > Looking at the code again, I am dubious you ever execute > the retry goto. If the PMU is disabled and you've just > cleared the OVF_STAT, then I don't see where the new > overflows would come from. But that's a separate problem.
I agree with you, but a printk before the goto proved otherwise! :-)
And a printk of the status bit that triggered the goto happened to be the same one that we initially cleared. Like I said when I initially posted the patch, I am not sure why it works but it does do something to stem the NMI.
There is probably a deeper problem here, I was just trying to get the external/unknown nmis working again.
Cheers, Don -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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