sched/core: Add trace point for cpu isolation

Add tracepoint to capture the cpu isolation event including KPI for
time it took to isolate.

Change-Id: If2d30000f068afc50db953940f4636ef6a089b24
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>

2 files changed, 47 insertions, 0 deletions

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 1ef5ec3eaf70..3990efdd0cc0 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -1244,6 +1244,41 @@ TRACE_EVENT(sched_get_nr_running_avg,
 		__entry->avg, __entry->big_avg, __entry->iowait_avg)
 );
 
+/**
+ * sched_isolate - called when cores are isolated/unisolated
+ *
+ * @acutal_mask: mask of cores actually isolated/unisolated
+ * @req_mask: mask of cores requested isolated/unisolated
+ * @online_mask: cpu online mask
+ * @time: amount of time in us it took to isolate/unisolate
+ * @isolate: 1 if isolating, 0 if unisolating
+ *
+ */
+TRACE_EVENT(sched_isolate,
+
+	TP_PROTO(unsigned int requested_cpu, unsigned int isolated_cpus,
+		 u64 start_time, unsigned char isolate),
+
+	TP_ARGS(requested_cpu, isolated_cpus, start_time, isolate),
+
+	TP_STRUCT__entry(
+		__field(u32, requested_cpu)
+		__field(u32, isolated_cpus)
+		__field(u32, time)
+		__field(unsigned char, isolate)
+	),
+
+	TP_fast_assign(
+		__entry->requested_cpu = requested_cpu;
+		__entry->isolated_cpus = isolated_cpus;
+		__entry->time = div64_u64(sched_clock() - start_time, 1000);
+		__entry->isolate = isolate;
+	),
+
+	TP_printk("iso cpu=%u cpus=0x%x time=%u us isolated=%d",
+		  __entry->requested_cpu, __entry->isolated_cpus,
+		  __entry->time, __entry->isolate)
+);
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cddb0073c5fb..7b7f1961fd10 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5645,6 +5645,10 @@ int sched_isolate_cpu(int cpu)
 	struct rq *rq = cpu_rq(cpu);
 	cpumask_t avail_cpus;
 	int ret_code = 0;
+	u64 start_time;
+
+	if (trace_sched_isolate_enabled())
+		start_time = sched_clock();
 
 	lock_device_hotplug();
 
@@ -5681,6 +5685,8 @@ int sched_isolate_cpu(int cpu)
 
 out:
 	unlock_device_hotplug();
+	trace_sched_isolate(cpu, cpumask_bits(cpu_isolated_mask)[0],
+			    start_time, 1);
 	return ret_code;
 }
 
@@ -5694,6 +5700,10 @@ int sched_unisolate_cpu_unlocked(int cpu)
 {
 	int ret_code = 0;
 	struct rq *rq = cpu_rq(cpu);
+	u64 start_time;
+
+	if (trace_sched_isolate_enabled())
+		start_time = sched_clock();
 
 	lock_device_hotplug_assert();
 
@@ -5730,6 +5740,8 @@ int sched_unisolate_cpu_unlocked(int cpu)
 	}
 
 out:
+	trace_sched_isolate(cpu, cpumask_bits(cpu_isolated_mask)[0],
+			    start_time, 0);
 	return ret_code;
 }