[PATCH 19/34] perf, x86: Support for printing PMU state on spurious PMIs v2

Andi Kleen
2012-10-18T23:27:56Z

I had some problems with spurious PMIs, so print the PMU state
on a spurious one. This will not interact well with other NMI users.
Disabled by default, has to be explicitely enabled through sysfs.

Optional, but useful for debugging.

v2: Move to /sys/devices/cpu
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/kernel/cpu/perf_event.c | 3 +++
arch/x86/kernel/cpu/perf_event.h | 2 ++
arch/x86/kernel/cpu/perf_event_intel.c | 4 ++++
3 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 87c2ab0..b0f4edd 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -38,6 +38,7 @@
#include "perf_event.h"

struct x86_pmu x86_pmu __read_mostly;
+int print_spurious_pmi __read_mostly;

DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
.enabled = 1,
@@ -1630,9 +1631,11 @@ static ssize_t set_attr_rdpmc(struct device *cdev,
}

static DEVICE_ATTR(rdpmc, S_IRUSR | S_IWUSR, get_attr_rdpmc, set_attr_rdpmc);
+static DEVICE_INT_ATTR(print_spurious_pmi, 0644, print_spurious_pmi);

static struct attribute *x86_pmu_attrs[] = {
&dev_attr_rdpmc.attr,
+ &dev_attr_print_spurious_pmi.attr.attr,
NULL,
};

diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h
index 89394e1..7b43503 100644
--- a/arch/x86/kernel/cpu/perf_event.h
+++ b/arch/x86/kernel/cpu/perf_event.h
@@ -659,3 +659,5 @@ static inline struct intel_shared_regs *allocate_shared_regs(int cpu)
}

#endif /* CONFIG_CPU_SUP_INTEL */
+
+extern int print_spurious_pmi;
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 957c5ea..274ed2c 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1205,6 +1205,10 @@ again:
goto again;

done:
+ if (!handled && print_spurious_pmi) {
+ pr_debug("Spurious PMI\n");
+ perf_event_print_debug();
+ }
intel_pmu_enable_all(0);
return handled;
}
--
1.7.7.6