power: Add power states to ClockedObject

Add 4 power states to the ClockedObject, provides necessary access functions
to check and update the power state. Default power state is UNDEFINED, it is
responsibility of the respective simulation model to provide the startup state
and any other logic for state change.

Add number of transition stat.
Add distribution of time spent in clock gated state.
Add power state residency stat.

Add dump call back function to allow stats update of distribution and residency
stats.

1 files changed, 177 insertions, 0 deletions

diff --git a/src/sim/clocked_object.cc b/src/sim/clocked_object.cc
new file mode 100644
index 000000000..9a682a4ce
--- /dev/null
+++ b/src/sim/clocked_object.cc
@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2015 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: Akash Bagdia
+ *          David Guillen Fandos
+ */
+
+#include "sim/clocked_object.hh"
+
+#include "base/misc.hh"
+
+void
+ClockedObject::serialize(CheckpointOut &cp) const
+{
+    unsigned int currPwrState = (unsigned int)_currPwrState;
+
+    SERIALIZE_SCALAR(currPwrState);
+    SERIALIZE_SCALAR(prvEvalTick);
+}
+
+void
+ClockedObject::unserialize(CheckpointIn &cp)
+{
+    unsigned int currPwrState;
+
+    UNSERIALIZE_SCALAR(currPwrState);
+    UNSERIALIZE_SCALAR(prvEvalTick);
+
+    _currPwrState = Enums::PwrState(currPwrState);
+}
+
+void
+ClockedObject::pwrState(Enums::PwrState p)
+{
+    // Function should ideally be called only when there is a state change
+    if (_currPwrState == p) {
+        warn("ClockedObject: Already in the requested power state, request "\
+             "ignored");
+        return;
+    }
+
+    // No need to compute stats if in the same tick, update state
+    // though. This can happen in cases like a) during start of the
+    // simulation multiple state changes happens in init/startup phase,
+    // b) one takes a decision to migrate state but decides to reverts
+    // back to the original state in the same tick if other conditions
+    // are not met elsewhere. Any state change related stats would have
+    // been recorded on previous call to the pwrState() function.
+    if (prvEvalTick == curTick()) {
+        warn("ClockedObject: More than one power state change request "\
+             "encountered within the same simulation tick");
+        _currPwrState = p;
+        return;
+    }
+
+    // Record stats for previous state.
+    computeStats();
+
+    _currPwrState = p;
+
+    numPwrStateTransitions++;
+}
+
+void
+ClockedObject::computeStats()
+{
+    // Calculate time elapsed from last (valid) state change
+    Tick elapsed_time = curTick() - prvEvalTick;
+
+    pwrStateResidencyTicks[_currPwrState] += elapsed_time;
+
+    // Time spent in CLK_GATED state, this might change depending on
+    // transition to other low power states in respective simulation
+    // objects.
+    if (_currPwrState == Enums::PwrState::CLK_GATED) {
+        pwrStateClkGateDist.sample(elapsed_time);
+    }
+
+    prvEvalTick = curTick();
+}
+
+std::vector<double>
+ClockedObject::pwrStateWeights() const
+{
+    // Get residency stats
+    std::vector<double> ret;
+    Stats::VCounter residencies;
+    pwrStateResidencyTicks.value(residencies);
+
+    // Account for current state too!
+    Tick elapsed_time = curTick() - prvEvalTick;
+    residencies[_currPwrState] += elapsed_time;
+
+    ret.resize(Enums::PwrState::Num_PwrState);
+    for (unsigned i = 0; i < Enums::PwrState::Num_PwrState; i++)
+        ret[i] = residencies[i] /
+                     (pwrStateResidencyTicks.total() + elapsed_time);
+
+    return ret;
+}
+
+void
+ClockedObject::regStats()
+{
+    SimObject::regStats();
+
+    using namespace Stats;
+
+    numPwrStateTransitions
+        .name(params()->name + ".numPwrStateTransitions")
+        .desc("Number of power state transitions")
+        ;
+
+    // Each sample is time in ticks
+    unsigned num_bins = std::max(params()->p_state_clk_gate_bins, 10U);
+    pwrStateClkGateDist
+        .init(params()->p_state_clk_gate_min, params()->p_state_clk_gate_max,
+          (params()->p_state_clk_gate_max / num_bins))
+        .name(params()->name + ".pwrStateClkGateDist")
+        .desc("Distribution of time spent in the clock gated state")
+        .flags(pdf)
+        ;
+
+    pwrStateResidencyTicks
+        .init(Enums::PwrState::Num_PwrState)
+        .name(params()->name + ".pwrStateResidencyTicks")
+        .desc("Cumulative time (in ticks) in various power states")
+        ;
+    for (int i = 0; i < Enums::PwrState::Num_PwrState; i++) {
+        pwrStateResidencyTicks.subname(i, Enums::PwrStateStrings[i]);
+    }
+
+    numPwrStateTransitions = 0;
+
+    /**
+     * For every stats dump, the power state residency and other distribution
+     * stats should be computed just before the dump to ensure correct stats
+     * value being reported for current dump window. It avoids things like
+     * having any unreported time spent in a power state to be forwarded to the
+     * next dump window which might have rather unpleasant effects (like
+     * perturbing the distribution stats).
+     */
+    registerDumpCallback(new ClockedObjectDumpCallback(this));
+}