If an arch supports counting of SMIs (like newer intel chips do), then it
can implement arch_smi_count() to return the number of SMIs that were
triggered. The hwlat detector will call this function to get the current
number of SMIs, and then after a period, it will read that function again,
and if there's a difference, it will record that into the sample.
For example:
[99] inner:13 outer:16 ts:1470352534.886878855
[100] inner:14 outer:18747 ts:1470352538.917966818 smi-count:2
[101] inner:0 outer:19162 ts:1470352539.920988709 smi-count:6
[102] inner:19376 outer:19276 ts:1470352540.923010578 smi-count:6
[103] inner:19650 outer:20665 ts:1470352541.926032469 smi-count:6
[104] inner:20526 outer:20680 ts:1470352542.973055312 smi-count:6
[105] inner:17 outer:17 ts:1470352543.990077507
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
arch/x86/events/msr.c | 12 ++++++++++++
kernel/trace/trace_entries.h | 1 +
kernel/trace/trace_hwlat.c | 11 +++++++++++
kernel/trace/trace_output.c | 4 ++++
4 files changed, 28 insertions(+)
diff --git a/arch/x86/events/msr.c b/arch/x86/events/msr.c
index 85ef3c2e80e0..ff0c6e6351b0 100644
--- a/arch/x86/events/msr.c
+++ b/arch/x86/events/msr.c
@@ -27,6 +27,18 @@ static bool test_irperf(int idx)
return boot_cpu_has(X86_FEATURE_IRPERF);
}
+int arch_smi_count(void)
+{
+ unsigned long long count;
+ int err;
+
+ err = rdmsrl_safe(MSR_SMI_COUNT, &count);
+ if (err)
+ return 0;
+
+ return count;
+}
+
static bool test_intel(int idx)
{
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index d1cc37e78f99..207faa837d3d 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -335,6 +335,7 @@ FTRACE_ENTRY(hwlat, hwlat_entry,
__field_desc( long, timestamp, tv_sec )
__field_desc( long, timestamp, tv_nsec )
__field( unsigned int, nmi_count )
+ __field( unsigned int, smi_count )
__field( unsigned int, seqnum )
),
diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index 2a668e55dcc6..1d60ef5c404f 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -69,6 +69,7 @@ static u64 nmi_ts_start;
static u64 nmi_total_ts;
static int nmi_count;
static int nmi_cpu;
+static int smi_count;
/* Tells NMIs to call back to the hwlat tracer to record timestamps */
bool trace_hwlat_callback_enabled;
@@ -84,6 +85,7 @@ struct hwlat_sample {
u64 nmi_total_ts; /* Total time spent in NMIs */
struct timespec timestamp; /* wall time */
int nmi_count; /* # NMIs during this sample */
+ int smi_count; /* # SMIs during sampling (if arch supported) */
};
/* keep the global state somewhere. */
@@ -125,6 +127,7 @@ static void trace_hwlat_sample(struct hwlat_sample *sample)
entry->timestamp = sample->timestamp;
entry->nmi_total_ts = sample->nmi_total_ts;
entry->nmi_count = sample->nmi_count;
+ entry->smi_count = sample->smi_count;
if (!call_filter_check_discard(call, entry, buffer, event))
__buffer_unlock_commit(buffer, event);
@@ -138,6 +141,11 @@ static void trace_hwlat_sample(struct hwlat_sample *sample)
#define init_time(a, b) (a = b)
#define time_u64(a) a
+__weak unsigned long long arch_smi_count(void)
+{
+ return 0;
+}
+
void trace_hwlat_callback(bool enter)
{
if (smp_processor_id() != nmi_cpu)
@@ -180,6 +188,7 @@ static int get_sample(void)
nmi_cpu = smp_processor_id();
nmi_total_ts = 0;
nmi_count = 0;
+ smi_count = arch_smi_count();
/* Make sure NMIs see this first */
barrier();
@@ -231,6 +240,7 @@ static int get_sample(void)
barrier(); /* finish the above in the view for NMIs */
trace_hwlat_callback_enabled = false;
+ smi_count = arch_smi_count() - smi_count;
barrier(); /* Make sure nmi_total_ts is no longer updated */
ret = 0;
@@ -252,6 +262,7 @@ static int get_sample(void)
s.timestamp = CURRENT_TIME;
s.nmi_total_ts = nmi_total_ts;
s.nmi_count = nmi_count;
+ s.smi_count = smi_count;
trace_hwlat_sample(&s);
/* Keep a running maximum ever recorded hardware latency */
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 5478a97e8db3..498eb7363e05 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1128,6 +1128,10 @@ trace_hwlat_print(struct trace_iterator *iter, int flags,
field->nmi_count);
}
+ if (field->smi_count)
+ trace_seq_printf(s, " smi-count:%u",
+ field->smi_count);
+
trace_seq_putc(s, '\n');
return trace_handle_return(s);
--
1.9.3
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