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| author | Ingo Molnar <mingo@elte.hu> | 2011-05-01 19:09:39 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-05-01 19:09:39 +0200 |
| commit | 809435ff4f43a5c0cb0201b3b89176253d5ade18 (patch) | |
| tree | 607d673c02117656a956b54dd2bb80fe94edea61 /arch/x86/kernel/cpu/perf_event_p4.c | |
| parent | 32673822e440eb92eb334631eb0a199d0c532d13 (diff) | |
| parent | 058e297d34a404caaa5ed277de15698d8dc43000 (diff) | |
Merge branch 'tip/perf/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event_p4.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_p4.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c index f4c1da2f9352..ead584fb6a7d 100644 --- a/arch/x86/kernel/cpu/perf_event_p4.c +++ b/arch/x86/kernel/cpu/perf_event_p4.c @@ -946,14 +946,23 @@ static int p4_pmu_handle_irq(struct pt_regs *regs) if (!x86_perf_event_set_period(event)) continue; if (perf_event_overflow(event, 1, &data, regs)) - p4_pmu_disable_event(event); + x86_pmu_stop(event, 0); } - if (handled) { - /* p4 quirk: unmask it again */ - apic_write(APIC_LVTPC, apic_read(APIC_LVTPC) & ~APIC_LVT_MASKED); + if (handled) inc_irq_stat(apic_perf_irqs); - } + + /* + * When dealing with the unmasking of the LVTPC on P4 perf hw, it has + * been observed that the OVF bit flag has to be cleared first _before_ + * the LVTPC can be unmasked. + * + * The reason is the NMI line will continue to be asserted while the OVF + * bit is set. This causes a second NMI to generate if the LVTPC is + * unmasked before the OVF bit is cleared, leading to unknown NMI + * messages. + */ + apic_write(APIC_LVTPC, APIC_DM_NMI); return handled; } |