perf/x86/intel/lbr: Optimize v4 LBR unfreezing
In Arch perfmon v4 the GLOBAL_STATUS reset automatically unfreezes LBRs. So no need to do it manually in the LBR code. Add a check to skip it. v2: Move test up to beginning of function. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: eranian@google.com Link: http://lkml.kernel.org/r/1431285767-27027-9-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -140,6 +140,13 @@ static void __intel_pmu_lbr_enable(bool pmi)
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struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
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u64 debugctl, lbr_select = 0, orig_debugctl;
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/*
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* No need to unfreeze manually, as v4 can do that as part
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* of the GLOBAL_STATUS ack.
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*/
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if (pmi && x86_pmu.version >= 4)
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return;
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/*
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* No need to reprogram LBR_SELECT in a PMI, as it
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* did not change.
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