perf pmu-events: Make the metric_constraint an enum

Rename metric_constraint to event_grouping to better explain what the
variable is used for. Switch to use an enum for encoding instead of a
string. Rather than just no constraint/grouping information or
"NO_NMI_WATCHDOG", have 4 enum values. The values encode whether to
group or not, and two cases where the behavior is dependent on either
the NMI watchdog being enabled or SMT being enabled.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
Link: https://lore.kernel.org/r/20230219092848.639226-9-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/pmu-events/jevents.py

@@ -51,8 +51,8 @@ _json_event_attributes = [
 
 # Attributes that are in pmu_metric rather than pmu_event.
 _json_metric_attributes = [
-    'metric_name', 'metric_group', 'metric_constraint', 'metric_expr', 'desc',
-    'long_desc', 'unit', 'compat', 'aggr_mode'
+    'metric_name', 'metric_group', 'metric_expr', 'desc',
+    'long_desc', 'unit', 'compat', 'aggr_mode', 'event_grouping'
 ]
 
 def removesuffix(s: str, suffix: str) -> str:
@@ -204,6 +204,18 @@ class JsonEvent:
       }
       return aggr_mode_to_enum[aggr_mode]
 
+    def convert_metric_constraint(metric_constraint: str) -> Optional[str]:
+      """Returns the metric_event_groups enum value associated with the JSON string."""
+      if not metric_constraint:
+        return None
+      metric_constraint_to_enum = {
+          'NO_GROUP_EVENTS': '1',
+          'NO_GROUP_EVENTS_NMI': '2',
+          'NO_NMI_WATCHDOG': '2',
+          'NO_GROUP_EVENTS_SMT': '3',
+      }
+      return metric_constraint_to_enum[metric_constraint]
+
     def lookup_msr(num: str) -> Optional[str]:
       """Converts the msr number, or first in a list to the appropriate event field."""
       if not num:
@@ -288,7 +300,7 @@ class JsonEvent:
     self.deprecated = jd.get('Deprecated')
     self.metric_name = jd.get('MetricName')
     self.metric_group = jd.get('MetricGroup')
-    self.metric_constraint = jd.get('MetricConstraint')
+    self.event_grouping = convert_metric_constraint(jd.get('MetricConstraint'))
     self.metric_expr = None
     if 'MetricExpr' in jd:
       self.metric_expr = metric.ParsePerfJson(jd['MetricExpr']).Simplify()
@@ -678,7 +690,7 @@ static void decompress_event(int offset, struct pmu_event *pe)
 {
 \tconst char *p = &big_c_string[offset];
 """)
-  enum_attributes = ['aggr_mode', 'deprecated', 'perpkg']
+  enum_attributes = ['aggr_mode', 'deprecated', 'event_grouping', 'perpkg']
   for attr in _json_event_attributes:
     _args.output_file.write(f'\n\tpe->{attr} = ')
     if attr in enum_attributes:

tools/perf/pmu-events/pmu-events.h

@@ -11,6 +11,29 @@ enum aggr_mode_class {
 	PerCore
 };
 
+/**
+ * enum metric_event_groups - How events within a pmu_metric should be grouped.
+ */
+enum metric_event_groups {
+	/**
+	 * @MetricGroupEvents: Default, group events within the metric.
+	 */
+	MetricGroupEvents = 0,
+	/**
+	 * @MetricNoGroupEvents: Don't group events for the metric.
+	 */
+	MetricNoGroupEvents = 1,
+	/**
+	 * @MetricNoGroupEventsNmi: Don't group events for the metric if the NMI
+	 *                          watchdog is enabled.
+	 */
+	MetricNoGroupEventsNmi = 2,
+	/**
+	 * @MetricNoGroupEventsSmt: Don't group events for the metric if SMT is
+	 *                          enabled.
+	 */
+	MetricNoGroupEventsSmt = 3,
+};
 /*
  * Describe each PMU event. Each CPU has a table of PMU events.
  */
@@ -33,10 +56,10 @@ struct pmu_metric {
 	const char *metric_expr;
 	const char *unit;
 	const char *compat;
-	const char *metric_constraint;
 	const char *desc;
 	const char *long_desc;
 	enum aggr_mode_class aggr_mode;
+	enum metric_event_groups event_grouping;
 };
 
 struct pmu_events_table;

tools/perf/util/metricgroup.c

@@ -13,6 +13,7 @@
 #include "pmu.h"
 #include "pmu-hybrid.h"
 #include "print-events.h"
+#include "smt.h"
 #include "expr.h"
 #include "rblist.h"
 #include <string.h>
@@ -168,16 +169,20 @@ static void metric__watchdog_constraint_hint(const char *name, bool foot)
 
 static bool metric__group_events(const struct pmu_metric *pm)
 {
-	if (!pm->metric_constraint)
-		return true;
-
-	if (!strcmp(pm->metric_constraint, "NO_NMI_WATCHDOG") &&
-	    sysctl__nmi_watchdog_enabled()) {
+	switch (pm->event_grouping) {
+	case MetricNoGroupEvents:
+		return false;
+	case MetricNoGroupEventsNmi:
+		if (!sysctl__nmi_watchdog_enabled())
+			return true;
 		metric__watchdog_constraint_hint(pm->metric_name, /*foot=*/false);
 		return false;
+	case MetricNoGroupEventsSmt:
+		return !smt_on();
+	case MetricGroupEvents:
+	default:
+		return true;
 	}
-
-	return true;
 }
 
 static void metric__free(struct metric *m)