On Tue, Oct 31, 2006 at 02:55:50PM -0500, William Cohen wrote:
> Stephane Eranian wrote:
> >Gentlemen,
> >
> >On Tue, Oct 31, 2006 at 01:59:52PM -0500, William Cohen wrote:
> >
> >>This is being run on a 2.6.18 kernel with the perfmon patchs. The libpfm 
> >>is the snapshot from 060926. I don't know if this might be a version 
> >>issue, but it can't hurt to include those details. I reconfigured with 
> >>the additional option. I also turned on /sys/kernel/perfmon/debug (the 
> >>messages.txt file).
> >>
> >>
> >>PAPI_DEBUG=SUBSTRATE ./utils/papi_command_line PAPI_TOT_CYC >& 
> >>/tmp/output.txt
> >>
> >>It looks like the actual write to the pmc is the problem. I should add 
> >>that when I try to run pfmon after this that the machine locks up. I 
> >>assumpte that the is an oops. However, I have a GUI console so I can't 
> >>see the specific panic that is occurring on my laptop.
> >>
> >
> >Which machine is this run on, your AMD64 laptop?
> 
> Yes, this is an AMD64 laptop.
> 
> >>Oct 31 13:42:08 yugo kernel: perfmon: __pfm_write_pmcs.356: CPU0 [4670]: 
> >>pmc0 is not implemented/unaccessible
> >
> >
> >Your are trying to write pmc0. If on AMd64 or P6, pmc0 normally exist 
> >UNLESS you have the NMI watchdog turned
> >on. Take a look in /sys/kernel/perfmon/pmu_desc, if you do not have a pmc0 
> >subdir, then that is probably the
> >issue.
> >
> >I do not know how PAPI uses libpfm, but if you take a look at the 
> >examples, you will see that they pass a bitmask pfp_unavail_pmcs to 
> >pfm_dispatch_events(). This is the list of PMC that are not
> >available. Using this information libpfm, work around the PMC limitations. 
> >You need to populate
> >the bitmask, in the example subdir, take a look a detect_pmcs.c. I suspect 
> >PAPI is nott doing this, thus
> >libpfm returns an invalid assignment. Tools cannot assume they own the 
> >entire PMU, they need to query
> >what's available.
> >
> >Hope this helps.
> 
> Yes, the problem is definitely that pmc0 is not available and the PAPI code 
> is trying to blindly use it.
> 
> What is the magic operation to turn off the nmi watchdog?
> 
On the kernel cmdline append: nmi_watchdog=0

-- 
-Stephane
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