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It was noticed that P4 machines were generating double NMIs for each perf event. These extra NMIs lead to 'Dazed and confused' messages on the screen. I tracked this down to a P4 quirk that said the overflow bit had to be cleared before re-enabling the apic LVT mask. My first attempt was to move the un-masking inside the perf nmi handler from before the chipset NMI handler to after. This broke Nehalem boxes that seem to like the unmasking before the counters themselves are re-enabled. In order to keep this change simple for 2.6.39, I decided to just simply move the apic LVT un-masking to the beginning of all the chipset NMI handlers, with the exception of Pentium4's to fix the double NMI issue. Later on we can move the un-masking to later in the handlers to save a number of 'extra' NMIs on those particular chipsets. I tested this change on a P4 machine, an AMD machine, a Nehalem box, and a core2quad box. 'perf top' worked correctly along with various other small 'perf record' runs. Anything high stress breaks all the machines but that is a different problem. Thanks to various people for testing different versions of this patch. Reported-and-tested-by: Shaun Ruffell <sruffell@digium.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Link: http://lkml.kernel.org/r/1303900353-10242-1-git-send-email-dzickus@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu> CC: Cyrill Gorcunov <gorcunov@gmail.com> |
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| cpufreq | ||
| mcheck | ||
| mtrr | ||
| .gitignore | ||
| amd.c | ||
| bugs_64.c | ||
| bugs.c | ||
| centaur.c | ||
| common.c | ||
| cpu.h | ||
| cyrix.c | ||
| hypervisor.c | ||
| intel_cacheinfo.c | ||
| intel.c | ||
| Makefile | ||
| mkcapflags.pl | ||
| mshyperv.c | ||
| perf_event_amd.c | ||
| perf_event_intel_ds.c | ||
| perf_event_intel_lbr.c | ||
| perf_event_intel.c | ||
| perf_event_p4.c | ||
| perf_event_p6.c | ||
| perf_event.c | ||
| perfctr-watchdog.c | ||
| powerflags.c | ||
| proc.c | ||
| scattered.c | ||
| sched.c | ||
| topology.c | ||
| transmeta.c | ||
| umc.c | ||
| vmware.c | ||