From 58e9eaf06f5476cb2192ec1d012674ce5e79dd21 Mon Sep 17 00:00:00 2001 From: Vince Weaver Date: Fri, 19 Oct 2012 17:33:38 -0400 Subject: [PATCH] perf/x86: Remove P6 cpuc->enabled check Between 2.6.33 and 2.6.34 the PMU code was made modular. The x86_pmu_enable() call was extended to disable cpuc->enabled and iterate the counters, enabling one at a time, before calling enable_all() at the end, followed by re-enabling cpuc->enabled. Since cpuc->enabled was set to 0, that change effectively caused the "val |= ARCH_PERFMON_EVENTSEL_ENABLE;" code in p6_pmu_enable_event() and p6_pmu_disable_event() to be dead code that was never called. This change removes this code (which was confusing) and adds some extra commentary to make it more clear what is going on. Signed-off-by: Vince Weaver Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1210191732000.14552@vincent-weaver-1.um.maine.edu Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event_p6.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_p6.c b/arch/x86/kernel/cpu/perf_event_p6.c index 9582fcbcd8ec..7d0270bd793e 100644 --- a/arch/x86/kernel/cpu/perf_event_p6.c +++ b/arch/x86/kernel/cpu/perf_event_p6.c @@ -157,25 +157,25 @@ static void p6_pmu_enable_all(int added) static inline void p6_pmu_disable_event(struct perf_event *event) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); struct hw_perf_event *hwc = &event->hw; u64 val = P6_NOP_EVENT; - if (cpuc->enabled) - val |= ARCH_PERFMON_EVENTSEL_ENABLE; - (void)wrmsrl_safe(hwc->config_base, val); } static void p6_pmu_enable_event(struct perf_event *event) { - struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); struct hw_perf_event *hwc = &event->hw; u64 val; val = hwc->config; - if (cpuc->enabled) - val |= ARCH_PERFMON_EVENTSEL_ENABLE; + + /* + * p6 only has a global event enable, set on PerfEvtSel0 + * We "disable" events by programming P6_NOP_EVENT + * and we rely on p6_pmu_enable_all() being called + * to actually enable the events. + */ (void)wrmsrl_safe(hwc->config_base, val); } -- 2.20.1