Add more API set up for Mock GPU client. Also clean up previous mock GPU client

API.

PiperOrigin-RevId: 570153877

jax/_src/xla_bridge.py

@@ -84,6 +84,18 @@ _ROCM_VISIBLE_DEVICES = jax_config.DEFINE_string(
     'Restricts the set of ROCM devices that JAX will use. Either "all", or a '
     'comma-separate list of integer device IDs.')
 
+_USE_MOCK_GPU_CLIENT = jax_config.DEFINE_bool(
+    name="use_mock_gpu_client",
+    default=False,
+    help="If True, use a mock GPU client instead of a real one.",
+)
+
+_MOCK_NUM_GPUS = jax_config.DEFINE_integer(
+    name="mock_num_gpus",
+    default=1,
+    help="Mock GPU client number of gpus.",
+)
+
 
 # Backends
 
@@ -221,12 +233,28 @@ def make_gpu_client(
   if platform_name == "cuda":
     _check_cuda_versions()
 
+  if xla_extension_version <= 199:
+    return xla_client.make_gpu_client(
+        distributed_client=distributed.global_state.client,
+        node_id=distributed.global_state.process_id,
+        num_nodes=distributed.global_state.num_processes,
+        platform_name=platform_name,
+        allowed_devices=allowed_devices,
+    )
+  use_mock_gpu_client = _USE_MOCK_GPU_CLIENT.value
+  num_nodes = (
+      _MOCK_NUM_GPUS.value
+      if use_mock_gpu_client
+      else distributed.global_state.num_processes
+  )
+
   return xla_client.make_gpu_client(
       distributed_client=distributed.global_state.client,
       node_id=distributed.global_state.process_id,
-      num_nodes=distributed.global_state.num_processes,
+      num_nodes=num_nodes,
       platform_name=platform_name,
       allowed_devices=allowed_devices,
+      mock=use_mock_gpu_client,  # type: ignore[call-arg]
   )
 
 

tests/BUILD

@@ -231,6 +231,21 @@ jax_test(
     ],
 )
 
+jax_test(
+    name = "mock_gpu_test",
+    srcs = ["mock_gpu_test.py"],
+    disable_backends = [
+        "cpu",
+        "tpu",
+    ],
+    tags = [
+        "config-cuda-only",
+    ],
+    deps = [
+        "//jax:experimental",
+    ],
+)
+
 jax_test(
     name = "array_test",
     srcs = ["array_test.py"],

tests/mock_gpu_test.py

@@ -0,0 +1,69 @@
+# Copyright 2023 The JAX Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from functools import partial
+import math
+
+from absl.testing import absltest
+import jax
+from jax import config
+from jax._src import test_util as jtu
+from jax._src.lib import xla_extension_version
+import jax.numpy as jnp
+from jax.sharding import NamedSharding
+from jax.sharding import PartitionSpec as P
+import numpy as np
+
+config.parse_flags_with_absl()
+
+
+class MockGPUTest(jtu.JaxTestCase):
+
+  def setUp(self):
+    super().setUp()
+    jax.config.update('use_mock_gpu_client', True)
+
+  def tearDown(self):
+    jax.config.update('use_mock_gpu_client', False)
+    jax.config.update('mock_num_gpus', 1)
+    super().tearDown()
+
+  def testMockWithSharding(self):
+    if xla_extension_version < 200:
+      return
+    num_shards = 16
+    jax.config.update('mock_num_gpus', num_shards)
+    mesh_shape = (num_shards,)
+    axis_names = ('x',)
+    mesh_devices = np.array(jax.devices()).reshape(mesh_shape)
+    mesh = jax.sharding.Mesh(mesh_devices, axis_names)
+    @partial(
+        jax.jit,
+        in_shardings=NamedSharding(mesh, P('x',)),
+        out_shardings=NamedSharding(mesh, P('x',)),
+    )
+    def f(x, y):
+      z = x @ y
+      return z @ y
+
+    shape = (64, 64)
+    x = jnp.arange(math.prod(shape)).reshape(shape).astype(np.float32)
+    y = x + 1
+    f_lowered = f.lower(x, y)
+    hlo = f_lowered.compiler_ir()
+    self.assertIn('sharding = "{devices=[16,1]<=[16]}"', str(hlo))
+
+
+if __name__ == '__main__':
+  absltest.main(testLoader=jtu.JaxTestLoader())