cpu: Add a Python-enabled traffic generator

The current traffic generator relies on a configuration file that
describes a small machine to generate stimuli. This configuration file
is usually generated by the gem5 Python configuration. This creates an
unnecessary and fragile step.

This changeset introduces a Python-based trace module. When
instantiated, the module exposes a start method that takes an iterable
object as a parameter (e.g., a generator). The iterable object is
expected to represent a list of generators that will be run one after
the other. For example:

    system.tgen = PyTrafficGen()
    m5.instantiate()

    def trace():
        yield system.tgen.createIdle(1000)
        yield system.tgen.createExit(0)

    system.tgen.start(trace())

Change-Id: I58e60ca517e86c197859f4daaa67750066abdc1c
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11518
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>

1 files changed, 99 insertions, 0 deletions

diff --git a/src/cpu/testers/traffic_gen/pygen.cc b/src/cpu/testers/traffic_gen/pygen.cc
new file mode 100644
index 000000000..ce1d59130
--- /dev/null
+++ b/src/cpu/testers/traffic_gen/pygen.cc
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2018 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Andreas Sandberg
+ */
+#include "cpu/testers/traffic_gen/pygen.hh"
+
+#include "config/have_protobuf.hh"
+#include "debug/TrafficGen.hh"
+#include "params/PyTrafficGen.hh"
+#include "sim/init.hh"
+
+namespace py = pybind11;
+
+PyTrafficGen::PyTrafficGen(const PyTrafficGenParams *p)
+    : BaseTrafficGen(p)
+{
+}
+
+void
+PyTrafficGen::start(pybind11::object meta_generator)
+{
+    metaGenerator = meta_generator.begin();
+    BaseTrafficGen::start();
+}
+
+std::shared_ptr<BaseGen>
+PyTrafficGen::nextGenerator()
+{
+    if (!metaGenerator)
+        return std::shared_ptr<BaseGen>();
+
+    if (metaGenerator == py::iterator::sentinel()) {
+        DPRINTF(TrafficGen, "No more generators available.\n");
+        return std::shared_ptr<BaseGen>();
+    }
+
+    try {
+        DPRINTF(TrafficGen, "Casting to C++ base class.\n");
+        std::shared_ptr<BaseGen> gen =
+            metaGenerator->cast<std::shared_ptr<BaseGen>>();
+        metaGenerator++;
+        return gen;
+    } catch (py::cast_error) {
+        fatal("Meta generator didn't return a valid trace generator\n");
+    }
+}
+
+void
+pybind_init_tracers(py::module &m_native)
+{
+    using namespace pybind11::literals;
+
+    py::module m = m_native.def_submodule("trace");
+
+    py::class_<BaseGen, std::shared_ptr<BaseGen>> c_base(m, "BaseGen");
+}
+
+static EmbeddedPyBind _py_tracers("trace", pybind_init_tracers);
+
+PyTrafficGen*
+PyTrafficGenParams::create()
+{
+    return new PyTrafficGen(this);
+}
+