Ruby: Add new object called WireBuffer to mimic a Wire.

This is a substitute for MessageBuffers between controllers where you don't
want messages to actually go through the Network, because requests/responses can
always get reordered wrt to one another (even if you turn off Randomization and turn on Ordered)
because you are, after all, going through a network with contention. For systems where you model
multiple controllers that are very tightly coupled and do not actually go through a network,
it is a pain to have to write a coherence protocol to account for mixed up request/response orderings
despite the fact that it's completely unrealistic.  This is *not* meant as a substitute for real
MessageBuffers when messages do in fact go over a network.

1 files changed, 171 insertions, 0 deletions

diff --git a/src/mem/ruby/system/WireBuffer.cc b/src/mem/ruby/system/WireBuffer.cc
new file mode 100644
index 000000000..bab935c5d
--- /dev/null
+++ b/src/mem/ruby/system/WireBuffer.cc
@@ -0,0 +1,171 @@
+/*
+ * Copyright (c) 2010 Advanced Micro Devices, Inc.
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * Author:  Lisa Hsu
+ *
+ */
+
+#include <algorithm>
+#include <functional>
+
+#include "base/cprintf.hh"
+#include "base/stl_helpers.hh"
+#include "mem/ruby/system/WireBuffer.hh"
+
+using namespace std;
+
+class Consumer;
+
+
+// Output operator definition
+
+ostream&
+operator<<(ostream& out, const WireBuffer& obj)
+{
+    obj.print(out);
+    out << flush;
+    return out;
+}
+
+
+// ****************************************************************
+
+// CONSTRUCTOR
+WireBuffer::WireBuffer(const Params *p)
+    : SimObject(p)
+{
+    m_msg_counter = 0;
+}
+
+void
+WireBuffer::init()
+{
+}
+
+WireBuffer::~WireBuffer()
+{
+}
+
+void
+WireBuffer::enqueue(MsgPtr message, int latency)
+{
+    m_msg_counter++;
+    Time current_time = g_eventQueue_ptr->getTime();
+    Time arrival_time = current_time + latency;
+    assert(arrival_time > current_time);
+    MessageBufferNode thisNode(arrival_time, m_msg_counter, message);
+    m_message_queue.push_back(thisNode);
+    if (m_consumer_ptr != NULL) {
+        g_eventQueue_ptr->scheduleEventAbsolute(m_consumer_ptr, arrival_time);
+    } else {
+        panic("No Consumer for WireBuffer! %s\n", *this);
+    }
+}
+
+void
+WireBuffer::dequeue()
+{
+    assert(isReady());
+    pop_heap(m_message_queue.begin(), m_message_queue.end(),
+        greater<MessageBufferNode>());
+    m_message_queue.pop_back();
+}
+
+const Message*
+WireBuffer::peek()
+{
+    MessageBufferNode node = peekNode();
+    Message* msg_ptr = node.m_msgptr.get();
+    assert(msg_ptr != NULL);
+    return msg_ptr;
+}
+
+MessageBufferNode
+WireBuffer::peekNode()
+{
+    assert(isReady());
+    MessageBufferNode req = m_message_queue.front();
+    return req;
+}
+
+void
+WireBuffer::recycle()
+{
+    // Because you don't want anything reordered, make sure the recycle latency
+    // is just 1 cycle. As a result, you really want to use this only in
+    // Wire-like situations because you don't want to deadlock as a result of
+    // being stuck behind something if you're not actually supposed to.
+    assert(isReady());
+    MessageBufferNode node = m_message_queue.front();
+    pop_heap(m_message_queue.begin(), m_message_queue.end(),
+        greater<MessageBufferNode>());
+    node.m_time = g_eventQueue_ptr->getTime() + 1;
+    m_message_queue.back() = node;
+    push_heap(m_message_queue.begin(), m_message_queue.end(),
+        greater<MessageBufferNode>());
+    g_eventQueue_ptr->scheduleEventAbsolute(m_consumer_ptr,
+        g_eventQueue_ptr->getTime() + 1);
+}
+
+bool
+WireBuffer::isReady()
+{
+    return ((!m_message_queue.empty()) &&
+            (m_message_queue.front().m_time <= g_eventQueue_ptr->getTime()));
+}
+
+void
+WireBuffer::print(ostream& out) const
+{
+}
+
+void
+WireBuffer::printConfig(ostream& out)
+{
+}
+
+void
+WireBuffer::clearStats() const
+{
+}
+
+void
+WireBuffer::printStats(ostream& out) const
+{
+}
+
+void
+WireBuffer::wakeup()
+{
+}
+
+WireBuffer *
+RubyWireBufferParams::create()
+{
+    return new WireBuffer(this);
+}
+