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Date: Fri, 9 Mar 2012 05:23:35 -0800 From: tip-bot for Stephane Eranian <eranian@...gle.com> To: linux-tip-commits@...r.kernel.org Cc: linux-kernel@...r.kernel.org, eranian@...gle.com, hpa@...or.com, mingo@...hat.com, a.p.zijlstra@...llo.nl, tglx@...utronix.de, mingo@...e.hu Subject: [tip:perf/hw-branch-sampling] perf/x86: Disable LBR support for older Intel Atom processors Commit-ID: 88c9a65e13f393fd60d8b9e9c659a34f9e39967d Gitweb: http://git.kernel.org/tip/88c9a65e13f393fd60d8b9e9c659a34f9e39967d Author: Stephane Eranian <eranian@...gle.com> AuthorDate: Thu, 9 Feb 2012 23:20:56 +0100 Committer: Ingo Molnar <mingo@...e.hu> CommitDate: Mon, 5 Mar 2012 14:55:41 +0100 perf/x86: Disable LBR support for older Intel Atom processors The patch adds a restriction for Intel Atom LBR support. Only steppings 10 (PineView) and more recent are supported. Older models do not have a functional LBR. Their LBR does not freeze on PMU interrupt which makes LBR unusable in the context of perf_events. Signed-off-by: Stephane Eranian <eranian@...gle.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> Link: http://lkml.kernel.org/r/1328826068-11713-7-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar <mingo@...e.hu> --- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index e54a063..07f0ff8 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -315,6 +315,16 @@ void intel_pmu_lbr_init_snb(void) /* atom */ void intel_pmu_lbr_init_atom(void) { + /* + * only models starting at stepping 10 seems + * to have an operational LBR which can freeze + * on PMU interrupt + */ + if (boot_cpu_data.x86_mask < 10) { + pr_cont("LBR disabled due to erratum"); + return; + } + x86_pmu.lbr_nr = 8; x86_pmu.lbr_tos = MSR_LBR_TOS; x86_pmu.lbr_from = MSR_LBR_CORE_FROM; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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