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authormarkus.t.metzger@intel.com <markus.t.metzger@intel.com>2009-09-02 16:04:46 +0200
committerIngo Molnar <mingo@elte.hu>2009-09-04 09:26:39 +0200
commit747b50aaf728987732e6ff3ba10aba4acc4e0277 (patch)
treedd1b75f7d14b8bf7dff2519058516be69e70c356 /arch/x86/kernel
parentdc86cabe4b242446ea9aa8492c727e1220817898 (diff)
x86, perf_counter, bts: Fail if BTS is not available
Reserve PERF_COUNT_HW_BRANCH_INSTRUCTIONS with sample_period == 1 for BTS tracing and fail, if BTS is not available. Signed-off-by: Markus Metzger <markus.t.metzger@intel.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20090902140612.943801000@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/perf_counter.c25
1 files changed, 11 insertions, 14 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 396e35db705..2f41874ffb8 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -769,7 +769,7 @@ static int reserve_bts_hardware(void)
int cpu, err = 0;
if (!bts_available())
- return -EOPNOTSUPP;
+ return 0;
get_online_cpus();
@@ -914,7 +914,7 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
if (!reserve_pmc_hardware())
err = -EBUSY;
else
- reserve_bts_hardware();
+ err = reserve_bts_hardware();
}
if (!err)
atomic_inc(&active_counters);
@@ -979,6 +979,13 @@ static int __hw_perf_counter_init(struct perf_counter *counter)
if (config == -1LL)
return -EINVAL;
+ /*
+ * Branch tracing:
+ */
+ if ((attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS) &&
+ (hwc->sample_period == 1) && !bts_available())
+ return -EOPNOTSUPP;
+
hwc->config |= config;
return 0;
@@ -1355,19 +1362,9 @@ static int x86_pmu_enable(struct perf_counter *counter)
idx = fixed_mode_idx(counter, hwc);
if (idx == X86_PMC_IDX_FIXED_BTS) {
- /*
- * Try to use BTS for branch tracing. If that is not
- * available, try to get a generic counter.
- */
- if (unlikely(!cpuc->ds))
- goto try_generic;
-
- /*
- * Try to get the fixed counter, if that is already taken
- * then try to get a generic counter:
- */
+ /* BTS is already occupied. */
if (test_and_set_bit(idx, cpuc->used_mask))
- goto try_generic;
+ return -EAGAIN;
hwc->config_base = 0;
hwc->counter_base = 0;