Add script to verify the speedup from using multiple gpus.

theano/misc/check_multi_gpu.py

+#! /usr/bin/env python
+"""
+This file compare the runtime of two independent dot products on one
+and two GPU to measure the speedup.
+
+This should be 2x if the GPUs are equivalent.
+"""
+import time
+
+import numpy
+
+import pygpu
+import theano
+from theano.sandbox.gpuarray import init_dev
+from theano.sandbox.gpuarray.type import gpuarray_shared_constructor as shared
+from theano.sandbox.gpuarray.blas import gpu_dot22
+
+def main(dev1, dev2):
+    init_dev(dev1, 'ctx1')
+    init_dev(dev2, 'ctx2')
+
+    val1a = shared(numpy.random.randn(1024, 1024).astype('float32'),
+                   context_name='ctx1')
+    val1b = shared(numpy.random.randn(1024, 1024).astype('float32'),
+                   context_name='ctx1')
+    val1c = shared(numpy.random.randn(1024, 1024).astype('float32'),
+                   context_name='ctx1')
+    val1d = shared(numpy.random.randn(1024, 1024).astype('float32'),
+                   context_name='ctx1')
+
+    val2a = shared(numpy.random.randn(1024, 1024).astype('float32'),
+                   context_name='ctx2')
+    val2b = shared(numpy.random.randn(1024, 1024).astype('float32'),
+                   context_name='ctx2')
+
+    f1 = theano.function([], [gpu_dot22(val1a, val1b),
+                              gpu_dot22(val1c, val1d)])
+    f2 = theano.function([], [gpu_dot22(val1a, val1b),
+                              gpu_dot22(val2a, val2b)])
+
+    r = f1()
+    r[0].sync(), r[1].sync()
+    r = None
+    t = time.time()
+    r = f1()
+    r[0].sync(), r[1].sync()
+    t2 = time.time()
+    r = None
+
+    print "one ctx", t2 - t
+
+    r = f2()
+    r[0].sync(), r[1].sync()
+    r = None
+    t = time.time()
+    r = f2()
+    r[0].sync(), r[1].sync()
+    t2 = time.time()
+    r = None
+
+    print "two ctx", t2 - t
+
+if __name__ == '__main__':
+    import sys
+    if len(sys.argv) != 3:
+        raise ValueError("This script require two device names.")
+    main(sys.argv[1], sys.argv[2])