Benchmark: Add a silly throughput measurement tool

This tests the firmware with a busy USB stack, and measures how busy we're keeping it. By virtue of this being a stupid blocking USB client it won't actually be that busy, but this is a baseline at least.

tools/benchmark.py

@@ -13,29 +13,75 @@ import time, struct, sys
 dev = usb.core.find(idVendor=0x1d50, idProduct=0x607a)
 if not dev:
     raise IOError("No Fadecandy interfaces found")
-
 dev.set_configuration()
 
 print "Serial number: %s" % usb.util.get_string(dev, 255, dev.iSerialNumber)
 
-def readFrameCounter():
-    return struct.unpack('<I', dev.ctrl_transfer(0xC0, 0x01, 0, 0, 4, 1000))[0]
+def readCounter(index):
+    return struct.unpack('<I', dev.ctrl_transfer(0xC0, 0x01, 0, index, 4, 1000))[0]
+
+def counterDiff(c1, c2):
+    return (c2 - c1) & 0xFFFFFFFF
+
+def initLUT():
+    # Set up a default color LUT
+    lut = [0] * (64 * 25)
+    for index in range(25):
+        lut[index*64] = index | 0x40
+    lut[24*64] |= 0x20
+    for channel in range(3):
+        for row in range(257):
+            value = min(0xFFFF, int((row / 256.0) * 0x10000))
+            i = channel * 257 + row
+            packetNum = i / 31
+            packetIndex = i % 31
+            lut[packetNum*64 + 2 + packetIndex*2] = value & 0xFF
+            lut[packetNum*64 + 3 + packetIndex*2] = value >> 8
+    lutPackets = ''.join(map(chr, lut))
+    dev.write(1, lutPackets)
+    print "LUT programmed"
+
+def measureFrameRate():
+    sys.stderr.write("Calculating frame rate average...\n")
+    duration = 8.0
+    t1 = t2 = time.time()
+    c1 = readCounter(0)     # Rendered frames
+    k1 = readCounter(1)     # Received keyframes
+
+    # Dummy frames
+    data = ((chr(0 << 5) + chr(0x00) * 63) +
+            (chr(0 << 5) + chr(0x00) * 63) +
+            (chr(0 << 5) + chr(0x00) * 63) +
+            (chr(1 << 5) + chr(0x00) * 63) +
+            (chr(0 << 5) + chr(0x00) * 63) +
+            (chr(0 << 5) + chr(0x00) * 63) +
+            (chr(0 << 5) + chr(0x00) * 63) +
+            (chr(1 << 5) + chr(0x40) * 63)) * 100
+
+    # Use number of keyframes handled per second to estimate USB bandwidth
+    megabitsPerFrame = 64 * 4 * (8.0 / 1e6)
+
+    # Average the frame rate for up to 'duration' seconds.
+    try:
+        while (t2 - t1) < duration:
+            # Keep the EP1 OUT pipe full-ish, so we measure it while the USB driver is busy
+            dev.write(1, data)
+
+            t2 = time.time()
+            c2 = readCounter(0)
+            k2 = readCounter(1)
+
+            fps = counterDiff(c1, c2) / (t2 - t1)
+            mbps = counterDiff(k1, k2) * megabitsPerFrame / (t2 - t1)
 
-sys.stderr.write("Calculating frame rate average...\n")
-duration = 5.0
-t1 = t2 = time.time()
-c1 = readFrameCounter()
+            # Not sure how accurate this USB throughput is, the blocking write() is likely a problem.
+            sys.stderr.write("\r   %.2f FPS, %.2f Mbps  " % (fps, mbps))
 
-# Average the frame rate for up to 'duration' seconds.
-try:
-    while (t2 - t1) < duration:
-        time.sleep(0.1)
-        t2 = time.time()
-        c2 = readFrameCounter()
-        fps = ((c2 - c1) & 0xFFFFFFFF) / (t2 - t1)
-        sys.stderr.write("\r   %.2f FPS   " % fps)
-except KeyboardInterrupt:
-    pass
+    except KeyboardInterrupt:
+        pass
 
-sys.stderr.write("\n")
+    sys.stderr.write("\n")
+    return fps
 
+initLUT()
+measureFrameRate()