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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2011-04-26 13:24:33 +0200
committerIngo Molnar <mingo@elte.hu>2011-04-26 13:34:34 +0200
commit18a073a3acd3a47fbb5e23333df7fad28d576345 (patch)
tree7b961ab5fd0f98a2348e4eaa419838040d7f8034 /arch/x86
parentcd2e49e90f1cae7726c9a2c54488d881d7f1cd1c (diff)
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 <a.p.zijlstra@chello.nl> Reported-by: Ingo Molnar <mingo@elte.hu> Cc: "Metzger, Markus T" <markus.t.metzger@intel.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/n/tip-rd2y4ct71hjawzz6fpvsy9hg@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/cpu/perf_event.c4
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel.c3
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 632e5dc9c9c..fac0654021b 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 43fa20b1381..9194b0698d6 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);