From b68f1d2e7aa21029d73c7d453a8046e95d351740 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 17 May 2009 19:37:25 +0200 Subject: [PATCH] perf_counter, x86: speed up the scheduling fast-path We have to set up the LVT entry only at counter init time, not at every switch-in time. There's friction between NMI and non-NMI use here - we'll probably remove the per counter configurability of it - but until then, dont slow down things ... [ Impact: micro-optimization ] Cc: Peter Zijlstra Cc: Srivatsa Vaddagiri Cc: Paul Mackerras Cc: Corey Ashford Cc: Arnaldo Carvalho de Melo Cc: Marcelo Tosatti LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_counter.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 5bfd30ab3920..c109819c2cb9 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -285,6 +285,7 @@ static int __hw_perf_counter_init(struct perf_counter *counter) return -EACCES; hwc->nmi = 1; } + perf_counters_lapic_init(hwc->nmi); if (!hwc->irq_period) hwc->irq_period = x86_pmu.max_period; @@ -603,8 +604,6 @@ try_generic: hwc->counter_base = x86_pmu.perfctr; } - perf_counters_lapic_init(hwc->nmi); - x86_pmu.disable(hwc, idx); cpuc->counters[idx] = counter; @@ -1054,7 +1053,7 @@ void __init init_hw_perf_counters(void) pr_info("... counter mask: %016Lx\n", perf_counter_mask); - perf_counters_lapic_init(0); + perf_counters_lapic_init(1); register_die_notifier(&perf_counter_nmi_notifier); } -- 2.34.1