[PATCH V2 4/5] perf metricgroup: Support metric constraint

kan.liang
2020-02-24T22:00:47Z

From: Kan Liang <kan.liang@linux.intel.com>

Some metric groups have metric constraints. A metric group can be
scheduled as a group only when some constraints are applied.
For example, Page_Walks_Utilization has a metric constraint,
"NO_NMI_WATCHDOG".
When NMI watchdog is disabled, the metric group can be scheduled as a
group. Otherwise, splitting the metric group into standalone metrics.

Add a new function, metricgroup__has_constraint(), to check whether all
constraints are applied. If not, splitting the metric group into
standalone metrics.

Currently, only one constraint, "NO_NMI_WATCHDOG", is checked. Print a
warning for the metric group with the constraint, when NMI WATCHDOG is
enabled.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
tools/perf/util/metricgroup.c | 54 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index 1cd042c..c3a8c70 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -22,6 +22,8 @@
#include <linux/string.h>
#include <linux/zalloc.h>
#include <subcmd/parse-options.h>
+#include <api/fs/fs.h>
+#include "util.h"

struct metric_event *metricgroup__lookup(struct rblist *metric_events,
struct evsel *evsel,
@@ -429,6 +431,49 @@ static void metricgroup__add_metric_weak_group(struct strbuf *events,
strbuf_addf(events, "}:W");
}

+static void metricgroup__add_metric_non_group(struct strbuf *events,
+ const char **ids,
+ int idnum)
+{
+ int i;
+
+ for (i = 0; i < idnum; i++)
+ strbuf_addf(events, ",%s", ids[i]);
+}
+
+static void metricgroup___watchdog_constraint_hint(const char *name, bool foot)
+{
+ static bool violate_nmi_constraint;
+
+ if (!foot) {
+ pr_warning("Splitting metric group %s into standalone metrics.\n", name);
+ violate_nmi_constraint = true;
+ return;
+ }
+
+ if (!violate_nmi_constraint)
+ return;
+
+ pr_warning("Try disabling the NMI watchdog to comply NO_NMI_WATCHDOG metric constraint:\n"
+ " echo 0 > /proc/sys/kernel/nmi_watchdog\n"
+ " perf stat ...\n"
+ " echo 1 > /proc/sys/kernel/nmi_watchdog\n");
+}
+
+static bool metricgroup__has_constraint(struct pmu_event *pe)
+{
+ if (!pe->metric_constraint)
+ return false;
+
+ if (!strcmp(pe->metric_constraint, "NO_NMI_WATCHDOG") &&
+ sysctl__nmi_watchdog_enabled()) {
+ metricgroup___watchdog_constraint_hint(pe->metric_name, false);
+ return true;
+ }
+
+ return false;
+}
+
static int metricgroup__add_metric(const char *metric, struct strbuf *events,
struct list_head *group_list)
{
@@ -460,7 +505,10 @@ static int metricgroup__add_metric(const char *metric, struct strbuf *events,
if (events->len > 0)
strbuf_addf(events, ",");

- metricgroup__add_metric_weak_group(events, ids, idnum);
+ if (metricgroup__has_constraint(pe))
+ metricgroup__add_metric_non_group(events, ids, idnum);
+ else
+ metricgroup__add_metric_weak_group(events, ids, idnum);

eg = malloc(sizeof(struct egroup));
if (!eg) {
@@ -502,6 +550,10 @@ static int metricgroup__add_metric_list(const char *list, struct strbuf *events,
}
}
free(nlist);
+
+ if (!ret)
+ metricgroup___watchdog_constraint_hint(NULL, true);
+
return ret;
}

--
2.7.4