+/*
+ * Copyright (c) 2006 The Regents of The University of Michigan
+ * 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.
+ *
+ * Authors: Kevin Lim
+ */
#ifndef __CPU_ACTIVITY_HH__
#define __CPU_ACTIVITY_HH__
-#include "base/timebuf.hh"
#include "base/trace.hh"
-
-class ActivityRecorder {
+#include "cpu/timebuf.hh"
+
+/**
+ * ActivityRecorder helper class that informs the CPU if it can switch
+ * over to being idle or not. It works by having a time buffer as
+ * long as any time buffer in the CPU, and the CPU and all of its
+ * stages inform the ActivityRecorder when they write to any time
+ * buffer. The ActivityRecorder marks a 1 in the "0" slot of the time
+ * buffer any time a stage writes to a time buffer, and it advances
+ * its time buffer at the same time as all other stages. The
+ * ActivityRecorder also records if a stage has activity to do next
+ * cycle. The recorder keeps a count of these two. Thus any time the
+ * count is non-zero, there is either communication still in flight,
+ * or activity that still must be done, meaning that the CPU can not
+ * idle. If count is zero, then the CPU can safely idle as it has no
+ * more outstanding work to do.
+ */
+class ActivityRecorder
+{
public:
- ActivityRecorder(int num_stages, int longest_latency, int count);
+ ActivityRecorder(const std::string &name, int num_stages,
+ int longest_latency, int count);
+ ~ActivityRecorder();
/** Records that there is activity this cycle. */
void activity();
- /** Advances the activity buffer, decrementing the activityCount if active
- * communication just left the time buffer, and descheduling the CPU if
- * there is no activity.
+
+ /** Advances the activity buffer, decrementing the activityCount
+ * if active communication just left the time buffer, and
+ * determining if there is no activity.
*/
void advance();
+
/** Marks a stage as active. */
void activateStage(const int idx);
+
/** Deactivates a stage. */
void deactivateStage(const int idx);
- int getActivityCount() { return activityCount; }
+ /** Returns the activity status of a stage. */
+ bool getStageActive(const int idx) const { return stageActive[idx]; }
+
+ /** Returns the number of stages. */
+ int getNumStages() const { return numStages; }
+ /** Returns how many things are active within the recorder. */
+ int getActivityCount() const { return activityCount; }
+
+ /** Sets the count to a starting value. Can be used to disable
+ * the idling option.
+ */
void setActivityCount(int count)
{ activityCount = count; }
+ /** Returns if the CPU should be active. */
bool active() { return activityCount; }
+ /** Clears the time buffer and the activity count. */
void reset();
+ /** Debug function to dump the contents of the time buffer. */
void dump();
+ /** Debug function to ensure that the activity count matches the
+ * contents of the time buffer.
+ */
void validate();
+ const std::string &name() const { return _name; }
+
private:
+ // provide name() for DPRINTF.
+ std::string _name;
+
/** Time buffer that tracks if any cycles has active communication
* in them. It should be as long as the longest communication
* latency in the system. Each time any time buffer is written,
*/
TimeBuffer<bool> activityBuffer;
+ /** Longest latency time buffer in the CPU. */
int longestLatency;
/** Tracks how many stages and cycles of time buffer have
*/
int activityCount;
+ /** Number of stages that can be marked as active or inactive. */
int numStages;
/** Records which stages are active/inactive. */
projects / gem5.git / blobdiff