From 18a073a3acd3a47fbb5e23333df7fad28d576345 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 26 Apr 2011 13:24:33 +0200 Subject: [PATCH] perf, x86: Fix BTS condition Currently the x86 backend incorrectly assumes that any BRANCH_INSN with sample_period==1 is a BTS request. This is not true when we do frequency driven profiling such as 'perf record -e branches'. Solves this error: $ perf record -e branches ./array Error: sys_perf_event_open() syscall returned with 95 (Operation not supported). Signed-off-by: Peter Zijlstra Reported-by: Ingo Molnar Cc: "Metzger, Markus T" Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Link: http://lkml.kernel.org/n/tip-rd2y4ct71hjawzz6fpvsy9hg@git.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 4 ++-- arch/x86/kernel/cpu/perf_event_intel.c | 3 +++ 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 632e5dc..fac0654 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -613,8 +613,8 @@ static int x86_setup_perfctr(struct perf_event *event) /* * Branch tracing: */ - if ((attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS) && - (hwc->sample_period == 1)) { + if (attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS && + !attr->freq && hwc->sample_period == 1) { /* BTS is not supported by this architecture. */ if (!x86_pmu.bts_active) return -EOPNOTSUPP; diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index 43fa20b..9194b06 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -998,6 +998,9 @@ intel_bts_constraints(struct perf_event *event) struct hw_perf_event *hwc = &event->hw; unsigned int hw_event, bts_event; + if (event->attr.freq) + return NULL; + hw_event = hwc->config & INTEL_ARCH_EVENT_MASK; bts_event = x86_pmu.event_map(PERF_COUNT_HW_BRANCH_INSTRUCTIONS); -- 2.7.4