Simple CPU-time burner application

repos/os/src/app/cpu_burner/README

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+This directory contains a simple CPU burner. The percentage of CPU time to burn
+can be configured via its '<config>' attribute 'percent'.

repos/os/src/app/cpu_burner/main.cc

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+/*
+ * \brief  CPU burner
+ * \author Norman Feske
+ * \date   2015-06-30
+ */
+
+/*
+ * Copyright (C) 2015 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/* Genode includes */
+#include <os/config.h>
+#include <timer_session/connection.h>
+
+struct Cpu_burner
+{
+	Timer::Connection _timer;
+
+	unsigned long _percent = 100;
+
+	void _handle_config(unsigned)
+	{
+		Genode::config()->reload();
+
+		_percent = 100;
+		try {
+			Genode::config()->xml_node().attribute("percent").value(&_percent);
+		} catch (...) { }
+	}
+
+	Genode::Signal_dispatcher<Cpu_burner> _config_dispatcher;
+
+	unsigned _burn_per_iteration = 10;
+
+	void _handle_period(unsigned)
+	{
+		unsigned long const start_ms = _timer.elapsed_ms();
+
+		unsigned iterations = 0;
+		for (;; iterations++) {
+
+			unsigned long const curr_ms = _timer.elapsed_ms();
+			unsigned long passed_ms     = curr_ms - start_ms;
+
+			if (passed_ms >= 10*_percent)
+				break;
+
+			/* burn some time */
+			for (unsigned volatile i = 0; i < _burn_per_iteration; i++)
+				for (unsigned volatile j = 0; j < 1000*1000; j++)
+					(void) (i*j);
+		}
+
+		/* adjust busy loop duration */
+		if (iterations > 10)
+			_burn_per_iteration *= 2;
+
+		if (iterations < 5)
+			_burn_per_iteration /= 2;
+	}
+
+	Genode::Signal_dispatcher<Cpu_burner> _period_dispatcher;
+
+	Cpu_burner(Genode::Signal_receiver &sig_rec)
+	:
+		_config_dispatcher(sig_rec, *this, &Cpu_burner::_handle_config),
+		_period_dispatcher(sig_rec, *this, &Cpu_burner::_handle_period)
+	{
+		Genode::config()->sigh(_config_dispatcher);
+		_handle_config(0);
+
+		_timer.sigh(_period_dispatcher);
+		_timer.trigger_periodic(1000*1000);
+	}
+};
+
+
+int main(int argc, char **argv)
+{
+
+	static Genode::Signal_receiver sig_rec;
+
+	static Cpu_burner cpu_burner(sig_rec);
+
+	while (1) {
+
+		Genode::Signal signal = sig_rec.wait_for_signal();
+
+		Genode::Signal_dispatcher_base *dispatcher =
+			static_cast<Genode::Signal_dispatcher_base *>(signal.context());
+
+		dispatcher->dispatch(signal.num());
+	}
+}

repos/os/src/app/cpu_burner/target.mk

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+TARGET = cpu_burner
+SRC_CC = main.cc
+LIBS   = base config