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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>
This commit is contained in:
markus.t.metzger@intel.com 2009-09-02 16:04:46 +02:00 committed by Ingo Molnar
parent dc86cabe4b
commit 747b50aaf7
1 changed files with 11 additions and 14 deletions
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25
arch/x86/kernel/cpu/perf_counter.c
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@ -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;