examples: add pulse performance test

examples/pulse_performance.py

@@ -0,0 +1,34 @@
+from artiq import *
+from artiq.devices import corecom_serial, core, rtio_core
+from artiq.devices.runtime_exceptions import RTIOUnderflow
+
+
+def print_min_period(p):
+    print("Minimum square wave output period: {} ns".format(p))
+
+
+class PulsePerformance(AutoContext):
+    parameters = "o"
+
+    @kernel
+    def run(self):
+        T = time_to_cycles(100*ns)
+        while True:
+            try:
+                for i in range(1000):
+                    self.o.pulse(cycles_to_time(T))
+                    delay(cycles_to_time(T))
+            except RTIOUnderflow:
+                T += 1
+                delay(1*ms)
+            else:
+                print_min_period(int(cycles_to_time(2*T)/(1*ns)))
+                break
+
+
+if __name__ == "__main__":
+    with corecom_serial.CoreCom() as com:
+        coredev = core.Core(com)
+        exp = PulsePerformance(core=coredev,
+                               o=rtio_core.RTIOOut(core=coredev, channel=1))
+        exp.run()