Added process cpu use and per-core global cpu use to linux overlay.

src/util/ProcessorTime/ProcessorTime.cpp

@@ -0,0 +1,29 @@
+#include "util/ProcessorTime/ProcessorTime.h"
+
+uint64_t ProcessorTime::work()
+{
+	return user + kernel;
+}
+
+uint64_t ProcessorTime::total()
+{
+	return idle + user + kernel;
+}
+
+double ProcessorTime::Compare(ProcessorTime &last, ProcessorTime &now)
+{
+	auto dwork = now.work() - last.work();
+	auto dtotal = now.total() - last.total();
+
+	return (double)dwork / dtotal;
+}
+
+void QueryProcTime(ProcessorTime &out)
+{
+	uint64_t now, user, kernel;
+	QueryProcTime(now, user, kernel);
+
+	out.idle = now - (user + kernel);
+	out.kernel = kernel;
+	out.user = user;
+}