pwr: 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.

Change-Id: Id086090a2ed720c9fcb37812a3c98f0f724907c6

4 files changed, 263 insertions, 3 deletions

diff --git a/src/sim/ClockedObject.py b/src/sim/ClockedObject.py
index 2562f1f01..2b742ec1e 100644
--- a/src/sim/ClockedObject.py
+++ b/src/sim/ClockedObject.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2012 ARM Limited
+# Copyright (c) 2012, 2015-2016 ARM Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -39,6 +39,24 @@ from m5.SimObject import SimObject
 from m5.params import *
 from m5.proxy import *
 
+# Enumerate set of allowed power states that can be used by a clocked object.
+# The list is kept generic to express a base minimal set.
+# State definition :-
+#   Undefined: Invalid state, no power state derived information is available.
+#   On: The logic block is actively running and consuming dynamic and leakage
+#       energy depending on the amount of processing required.
+#   Clk_gated: The clock circuity within the block is gated to save dynamic
+#              energy, the power supply to the block is still on and leakage
+#              energy is being consumed by the block.
+#   Sram_retention: The SRAMs within the logic blocks are pulled into retention
+#                   state to reduce leakage energy further.
+#   Off: The logic block is power gated and is not consuming any energy.
+class PwrState(Enum): vals = ['UNDEFINED',
+                             'ON',
+                             'CLK_GATED',
+                             'SRAM_RETENTION',
+                             'OFF']
+
 class ClockedObject(SimObject):
     type = 'ClockedObject'
     abstract = True
@@ -47,3 +65,12 @@ class ClockedObject(SimObject):
     # The clock domain this clocked object belongs to, inheriting the
     # parent's clock domain by default
     clk_domain = Param.ClockDomain(Parent.clk_domain, "Clock domain")
+
+    # Provide initial power state, should ideally get redefined in startup
+    # routine
+    default_p_state = Param.PwrState("UNDEFINED", "Default Power State")
+
+    p_state_clk_gate_min = Param.Latency('1ns',"Min value of the distribution")
+    p_state_clk_gate_max = Param.Latency('1s',"Max value of the distribution")
+    p_state_clk_gate_bins = Param.Unsigned('20',
+        "# bins in clk gated distribution")
diff --git a/src/sim/SConscript b/src/sim/SConscript
index 3238301ed..e40c43f0c 100644
--- a/src/sim/SConscript
+++ b/src/sim/SConscript
@@ -69,6 +69,7 @@ Source('voltage_domain.cc')
 Source('linear_solver.cc')
 Source('system.cc')
 Source('dvfs_handler.cc')
+Source('clocked_object.cc')
 
 if env['TARGET_ISA'] != 'null':
     SimObject('InstTracer.py')
diff --git a/src/sim/clocked_object.cc b/src/sim/clocked_object.cc
new file mode 100644
index 000000000..19495b916
--- /dev/null
+++ b/src/sim/clocked_object.cc
@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2015-2016 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));
+}
diff --git a/src/sim/clocked_object.hh b/src/sim/clocked_object.hh
index b9a2481ec..30bc08cf4 100644
--- a/src/sim/clocked_object.hh
+++ b/src/sim/clocked_object.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2013 ARM Limited
+ * Copyright (c) 2012-2013, 2015-2016 ARM Limited
  * Copyright (c) 2013 Cornell University
  * All rights reserved
  *
@@ -37,6 +37,8 @@
  *
  * Authors: Andreas Hansson
  *          Christopher Torng
+ *          Akash Bagdia
+ *          David Guillen Fandos
  */
 
 /**
@@ -47,8 +49,10 @@
 #ifndef __SIM_CLOCKED_OBJECT_HH__
 #define __SIM_CLOCKED_OBJECT_HH__
 
+#include "base/callback.hh"
 #include "base/intmath.hh"
 #include "base/misc.hh"
+#include "enums/PwrState.hh"
 #include "params/ClockedObject.hh"
 #include "sim/core.hh"
 #include "sim/clock_domain.hh"
@@ -233,7 +237,58 @@ class ClockedObject
 {
   public:
     ClockedObject(const ClockedObjectParams *p)
-        : SimObject(p), Clocked(*p->clk_domain) { }
+        : SimObject(p), Clocked(*p->clk_domain),
+        _currPwrState(p->default_p_state),
+        prvEvalTick(0)
+    { }
+
+    /** Parameters of ClockedObject */
+    typedef ClockedObjectParams Params;
+    const Params* params() const
+    { return reinterpret_cast<const Params*>(_params); }
+
+    void serialize(CheckpointOut &cp) const override;
+    void unserialize(CheckpointIn &cp) override;
+
+    inline Enums::PwrState pwrState() const
+    { return _currPwrState; }
+
+    inline std::string pwrStateName() const
+    { return Enums::PwrStateStrings[_currPwrState]; }
+
+    /** Returns the percentage residency for each power state */
+    std::vector<double> pwrStateWeights() const;
+
+    /**
+     * Record stats values like state residency by computing the time
+     * difference from previous update. Also, updates the previous evaluation
+     * tick once all stats are recorded.
+     * Usually called on power state change and stats dump callback.
+     */
+    void computeStats();
+
+    void pwrState(Enums::PwrState);
+    void regStats();
+
+  protected:
+
+    /** To keep track of the current power state */
+    Enums::PwrState _currPwrState;
+
+    Tick prvEvalTick;
+
+    Stats::Scalar numPwrStateTransitions;
+    Stats::Distribution pwrStateClkGateDist;
+    Stats::Vector pwrStateResidencyTicks;
+
+};
+
+class ClockedObjectDumpCallback : public Callback
+{
+    ClockedObject *co;
+  public:
+    ClockedObjectDumpCallback(ClockedObject *co_t) : co(co_t) {}
+    virtual void process() { co->computeStats(); };
 };
 
 #endif //__SIM_CLOCKED_OBJECT_HH__