From: Stephane Eranian <eranian@google.com>
To: linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, mingo@elte.hu, acme@redhat.com,
robert.richter@amd.com, ming.m.lin@intel.com,
andi@firstfloor.org, asharma@fb.com, ravitillo@lbl.gov,
vweaver1@eecs.utk.edu, khandual@linux.vnet.ibm.com,
dsahern@gmail.com
Subject: [PATCH v4 06/18] perf: disable LBR support for older Intel Atom processors
Date: Fri, 27 Jan 2012 21:56:06 +0100 [thread overview]
Message-ID: <1327697778-18515-7-git-send-email-eranian@google.com> (raw)
In-Reply-To: <1327697778-18515-1-git-send-email-eranian@google.com>
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@google.com>
---
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 8a1eb6c..e2b7094 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -313,6 +313,16 @@ 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;
--
1.7.1
next prev parent reply other threads:[~2012-01-27 21:01 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 20:56 [PATCH v4 00/18] perf: add support for sampling taken branches Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 01/18] perf: add generic taken branch sampling support Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 02/18] perf: add Intel LBR MSR definitions Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 03/18] perf: add Intel X86 LBR sharing logic Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 04/18] perf: sync branch stack sampling with X86 precise_sampling Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 05/18] perf: add LBR mappings for PERF_SAMPLE_BRANCH filters Stephane Eranian
2012-01-27 20:56 ` Stephane Eranian [this message]
2012-01-27 20:56 ` [PATCH v4 07/18] perf: implement PERF_SAMPLE_BRANCH for Intel X86 Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 08/18] perf: add LBR software filter support " Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 09/18] perf: disable PERF_SAMPLE_BRANCH_* when not supported Stephane Eranian
2012-01-30 3:57 ` Anshuman Khandual
2012-01-27 20:56 ` [PATCH v4 10/18] perf: add hook to flush branch_stack on context switch Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 11/18] perf: add code to support PERF_SAMPLE_BRANCH_STACK Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 12/18] perf: add support for sampling taken branch to perf record Stephane Eranian
2012-01-31 9:47 ` Anshuman Khandual
2012-01-31 10:31 ` Stephane Eranian
2012-01-31 15:44 ` Anshuman Khandual
2012-01-31 15:48 ` Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 13/18] perf: add support for taken branch sampling to perf report Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 14/18] perf: fix endianness detection in perf.data Stephane Eranian
2012-01-30 5:55 ` Anshuman Khandual
2012-01-27 20:56 ` [PATCH v4 15/18] perf: add ABI reference sizes Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 16/18] perf: enable reading of perf.data files from different ABI rev Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 17/18] perf: fix bug print_event_desc() Stephane Eranian
2012-01-27 20:56 ` [PATCH v4 18/18] perf: make perf able to read file from older ABIs Stephane Eranian
2012-01-31 8:54 ` Anshuman Khandual
2012-01-30 4:16 ` [PATCH v4 00/18] perf: add support for sampling taken branches Anshuman Khandual
2012-01-30 10:15 ` Stephane Eranian
2012-02-01 8:41 ` Anshuman Khandual
2012-02-02 13:23 ` Stephane Eranian
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