drain.hh revision 11859
19342SAndreas.Sandberg@arm.com/* 210910Sandreas.sandberg@arm.com * Copyright (c) 2012, 2015 ARM Limited 39342SAndreas.Sandberg@arm.com * All rights reserved 49342SAndreas.Sandberg@arm.com * 59342SAndreas.Sandberg@arm.com * The license below extends only to copyright in the software and shall 69342SAndreas.Sandberg@arm.com * not be construed as granting a license to any other intellectual 79342SAndreas.Sandberg@arm.com * property including but not limited to intellectual property relating 89342SAndreas.Sandberg@arm.com * to a hardware implementation of the functionality of the software 99342SAndreas.Sandberg@arm.com * licensed hereunder. You may use the software subject to the license 109342SAndreas.Sandberg@arm.com * terms below provided that you ensure that this notice is replicated 119342SAndreas.Sandberg@arm.com * unmodified and in its entirety in all distributions of the software, 129342SAndreas.Sandberg@arm.com * modified or unmodified, in source code or in binary form. 139342SAndreas.Sandberg@arm.com * 149342SAndreas.Sandberg@arm.com * Redistribution and use in source and binary forms, with or without 159342SAndreas.Sandberg@arm.com * modification, are permitted provided that the following conditions are 169342SAndreas.Sandberg@arm.com * met: redistributions of source code must retain the above copyright 179342SAndreas.Sandberg@arm.com * notice, this list of conditions and the following disclaimer; 189342SAndreas.Sandberg@arm.com * redistributions in binary form must reproduce the above copyright 199342SAndreas.Sandberg@arm.com * notice, this list of conditions and the following disclaimer in the 209342SAndreas.Sandberg@arm.com * documentation and/or other materials provided with the distribution; 219342SAndreas.Sandberg@arm.com * neither the name of the copyright holders nor the names of its 229342SAndreas.Sandberg@arm.com * contributors may be used to endorse or promote products derived from 239342SAndreas.Sandberg@arm.com * this software without specific prior written permission. 249342SAndreas.Sandberg@arm.com * 259342SAndreas.Sandberg@arm.com * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 269342SAndreas.Sandberg@arm.com * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 279342SAndreas.Sandberg@arm.com * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 289342SAndreas.Sandberg@arm.com * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 299342SAndreas.Sandberg@arm.com * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 309342SAndreas.Sandberg@arm.com * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 319342SAndreas.Sandberg@arm.com * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 329342SAndreas.Sandberg@arm.com * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 339342SAndreas.Sandberg@arm.com * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 349342SAndreas.Sandberg@arm.com * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 359342SAndreas.Sandberg@arm.com * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 369342SAndreas.Sandberg@arm.com * 379342SAndreas.Sandberg@arm.com * Authors: Andreas Sandberg 389342SAndreas.Sandberg@arm.com */ 399342SAndreas.Sandberg@arm.com 409342SAndreas.Sandberg@arm.com#ifndef __SIM_DRAIN_HH__ 419342SAndreas.Sandberg@arm.com#define __SIM_DRAIN_HH__ 429342SAndreas.Sandberg@arm.com 4310912Sandreas.sandberg@arm.com#include <atomic> 4410912Sandreas.sandberg@arm.com#include <mutex> 4511859Sandreas.hansson@arm.com#include <vector> 469342SAndreas.Sandberg@arm.com 4710910Sandreas.sandberg@arm.comclass Drainable; 4810910Sandreas.sandberg@arm.com 4910910Sandreas.sandberg@arm.com#ifndef SWIG // SWIG doesn't support strongly typed enums 5010910Sandreas.sandberg@arm.com/** 5110910Sandreas.sandberg@arm.com * Object drain/handover states 5210910Sandreas.sandberg@arm.com * 5310910Sandreas.sandberg@arm.com * An object starts out in the Running state. When the simulator 5410910Sandreas.sandberg@arm.com * prepares to take a snapshot or prepares a CPU for handover, it 5510910Sandreas.sandberg@arm.com * calls the drain() method to transfer the object into the Draining 5610910Sandreas.sandberg@arm.com * or Drained state. If any object enters the Draining state 5710910Sandreas.sandberg@arm.com * (Drainable::drain() returning >0), simulation continues until it 5810910Sandreas.sandberg@arm.com * all objects have entered the Drained state. 5910910Sandreas.sandberg@arm.com * 6010910Sandreas.sandberg@arm.com * Before resuming simulation, the simulator calls resume() to 6110910Sandreas.sandberg@arm.com * transfer the object to the Running state. 6210910Sandreas.sandberg@arm.com * 6310910Sandreas.sandberg@arm.com * \note Even though the state of an object (visible to the rest of 6410910Sandreas.sandberg@arm.com * the world through Drainable::getState()) could be used to determine 6510910Sandreas.sandberg@arm.com * if all objects have entered the Drained state, the protocol is 6610910Sandreas.sandberg@arm.com * actually a bit more elaborate. See Drainable::drain() for details. 6710910Sandreas.sandberg@arm.com */ 6810910Sandreas.sandberg@arm.comenum class DrainState { 6910910Sandreas.sandberg@arm.com Running, /** Running normally */ 7010910Sandreas.sandberg@arm.com Draining, /** Draining buffers pending serialization/handover */ 7110910Sandreas.sandberg@arm.com Drained /** Buffers drained, ready for serialization/handover */ 7210910Sandreas.sandberg@arm.com}; 7310910Sandreas.sandberg@arm.com#endif 749342SAndreas.Sandberg@arm.com 759342SAndreas.Sandberg@arm.com/** 769342SAndreas.Sandberg@arm.com * This class coordinates draining of a System. 779342SAndreas.Sandberg@arm.com * 7810912Sandreas.sandberg@arm.com * When draining the simulator, we need to make sure that all 7910912Sandreas.sandberg@arm.com * Drainable objects within the system have ended up in the drained 8010912Sandreas.sandberg@arm.com * state before declaring the operation to be successful. This class 8110912Sandreas.sandberg@arm.com * keeps track of how many objects are still in the process of 8210912Sandreas.sandberg@arm.com * draining. Once it determines that all objects have drained their 8310912Sandreas.sandberg@arm.com * state, it exits the simulation loop. 849342SAndreas.Sandberg@arm.com * 859342SAndreas.Sandberg@arm.com * @note A System might not be completely drained even though the 869342SAndreas.Sandberg@arm.com * DrainManager has caused the simulation loop to exit. Draining needs 879342SAndreas.Sandberg@arm.com * to be restarted until all Drainable objects declare that they don't 889342SAndreas.Sandberg@arm.com * need further simulation to be completely drained. See Drainable for 899342SAndreas.Sandberg@arm.com * more information. 909342SAndreas.Sandberg@arm.com */ 919342SAndreas.Sandberg@arm.comclass DrainManager 929342SAndreas.Sandberg@arm.com{ 9310912Sandreas.sandberg@arm.com private: 9410912Sandreas.sandberg@arm.com DrainManager(); 9510912Sandreas.sandberg@arm.com#ifndef SWIG 9610912Sandreas.sandberg@arm.com DrainManager(DrainManager &) = delete; 9710912Sandreas.sandberg@arm.com#endif 9810912Sandreas.sandberg@arm.com ~DrainManager(); 9910912Sandreas.sandberg@arm.com 1009342SAndreas.Sandberg@arm.com public: 10110912Sandreas.sandberg@arm.com /** Get the singleton DrainManager instance */ 10210912Sandreas.sandberg@arm.com static DrainManager &instance() { return _instance; } 1039342SAndreas.Sandberg@arm.com 1049342SAndreas.Sandberg@arm.com /** 10510912Sandreas.sandberg@arm.com * Try to drain the system. 1069342SAndreas.Sandberg@arm.com * 10710912Sandreas.sandberg@arm.com * Try to drain the system and return true if all objects are in a 10810912Sandreas.sandberg@arm.com * the Drained state at which point the whole simulator is in a 10910912Sandreas.sandberg@arm.com * consistent state and ready for checkpointing or CPU 11010912Sandreas.sandberg@arm.com * handover. The simulation script must continue simulating until 11110912Sandreas.sandberg@arm.com * the simulation loop returns "Finished drain", at which point 11210912Sandreas.sandberg@arm.com * this method should be called again. This cycle should continue 11310912Sandreas.sandberg@arm.com * until this method returns true. 11410912Sandreas.sandberg@arm.com * 11510912Sandreas.sandberg@arm.com * @return true if all objects were drained successfully, false if 11610912Sandreas.sandberg@arm.com * more simulation is needed. 1179342SAndreas.Sandberg@arm.com */ 11810912Sandreas.sandberg@arm.com bool tryDrain(); 1199342SAndreas.Sandberg@arm.com 12010912Sandreas.sandberg@arm.com /** 12110912Sandreas.sandberg@arm.com * Resume normal simulation in a Drained system. 12210912Sandreas.sandberg@arm.com */ 12310912Sandreas.sandberg@arm.com void resume(); 12410912Sandreas.sandberg@arm.com 12510912Sandreas.sandberg@arm.com /** 12610912Sandreas.sandberg@arm.com * Run state fixups before a checkpoint restore operation 12710912Sandreas.sandberg@arm.com * 12810912Sandreas.sandberg@arm.com * The drain state of an object isn't stored in a checkpoint since 12910912Sandreas.sandberg@arm.com * the whole system is always going to be in the Drained state 13010912Sandreas.sandberg@arm.com * when the checkpoint is created. When the checkpoint is restored 13110912Sandreas.sandberg@arm.com * at a later stage, recreated objects will be in the Running 13210912Sandreas.sandberg@arm.com * state since the state isn't stored in checkpoints. This method 13310912Sandreas.sandberg@arm.com * performs state fixups on all Drainable objects and the 13410912Sandreas.sandberg@arm.com * DrainManager itself. 13510912Sandreas.sandberg@arm.com */ 13610912Sandreas.sandberg@arm.com void preCheckpointRestore(); 13710912Sandreas.sandberg@arm.com 13810912Sandreas.sandberg@arm.com /** Check if the system is drained */ 13911002Sandreas.sandberg@arm.com bool isDrained() const { return _state == DrainState::Drained; } 14010912Sandreas.sandberg@arm.com 14110912Sandreas.sandberg@arm.com /** Get the simulators global drain state */ 14211002Sandreas.sandberg@arm.com DrainState state() const { return _state; } 1439342SAndreas.Sandberg@arm.com 1449342SAndreas.Sandberg@arm.com /** 1459342SAndreas.Sandberg@arm.com * Notify the DrainManager that a Drainable object has finished 1469342SAndreas.Sandberg@arm.com * draining. 1479342SAndreas.Sandberg@arm.com */ 14810912Sandreas.sandberg@arm.com void signalDrainDone(); 1499342SAndreas.Sandberg@arm.com 15010912Sandreas.sandberg@arm.com public: 15110912Sandreas.sandberg@arm.com void registerDrainable(Drainable *obj); 15210912Sandreas.sandberg@arm.com void unregisterDrainable(Drainable *obj); 15310912Sandreas.sandberg@arm.com 15410912Sandreas.sandberg@arm.com private: 1559342SAndreas.Sandberg@arm.com /** 15610912Sandreas.sandberg@arm.com * Thread-safe helper function to get the number of Drainable 15710912Sandreas.sandberg@arm.com * objects in a system. 1589342SAndreas.Sandberg@arm.com */ 15910912Sandreas.sandberg@arm.com size_t drainableCount() const; 1609342SAndreas.Sandberg@arm.com 16110912Sandreas.sandberg@arm.com /** Lock protecting the set of drainable objects */ 16210912Sandreas.sandberg@arm.com mutable std::mutex globalLock; 16310912Sandreas.sandberg@arm.com 16410912Sandreas.sandberg@arm.com /** Set of all drainable objects */ 16511859Sandreas.hansson@arm.com std::vector<Drainable *> _allDrainable; 16610912Sandreas.sandberg@arm.com 16710912Sandreas.sandberg@arm.com /** 16810912Sandreas.sandberg@arm.com * Number of objects still draining. This is flagged atomic since 16910912Sandreas.sandberg@arm.com * it can be manipulated by SimObjects living in different 17010912Sandreas.sandberg@arm.com * threads. 17110912Sandreas.sandberg@arm.com */ 17210912Sandreas.sandberg@arm.com std::atomic_uint _count; 17310912Sandreas.sandberg@arm.com 17410912Sandreas.sandberg@arm.com /** Global simulator drain state */ 17510912Sandreas.sandberg@arm.com DrainState _state; 17610912Sandreas.sandberg@arm.com 17710912Sandreas.sandberg@arm.com /** Singleton instance of the drain manager */ 17810912Sandreas.sandberg@arm.com static DrainManager _instance; 1799342SAndreas.Sandberg@arm.com}; 1809342SAndreas.Sandberg@arm.com 1819342SAndreas.Sandberg@arm.com/** 1829342SAndreas.Sandberg@arm.com * Interface for objects that might require draining before 1839342SAndreas.Sandberg@arm.com * checkpointing. 1849342SAndreas.Sandberg@arm.com * 1859342SAndreas.Sandberg@arm.com * An object's internal state needs to be drained when creating a 1869342SAndreas.Sandberg@arm.com * checkpoint, switching between CPU models, or switching between 1879342SAndreas.Sandberg@arm.com * timing models. Once the internal state has been drained from 18810912Sandreas.sandberg@arm.com * <i>all</i> objects in the simulator, the objects are serialized to 1899342SAndreas.Sandberg@arm.com * disc or the configuration change takes place. The process works as 1909342SAndreas.Sandberg@arm.com * follows (see simulate.py for details): 1919342SAndreas.Sandberg@arm.com * 1929342SAndreas.Sandberg@arm.com * <ol> 19310913Sandreas.sandberg@arm.com * <li>DrainManager::tryDrain() calls Drainable::drain() for every 19410913Sandreas.sandberg@arm.com * object in the system. Draining has completed if all of them 19510913Sandreas.sandberg@arm.com * return true. Otherwise, the drain manager keeps track of the 19610913Sandreas.sandberg@arm.com * objects that requested draining and waits for them to signal 19710913Sandreas.sandberg@arm.com * that they are done draining using the signalDrainDone() method. 1989342SAndreas.Sandberg@arm.com * 1999342SAndreas.Sandberg@arm.com * <li>Continue simulation. When an object has finished draining its 20010912Sandreas.sandberg@arm.com * internal state, it calls DrainManager::signalDrainDone() on the 20110913Sandreas.sandberg@arm.com * manager. The drain manager keeps track of the objects that 20210913Sandreas.sandberg@arm.com * haven't drained yet, simulation stops when the set of 20310913Sandreas.sandberg@arm.com * non-drained objects becomes empty. 2049342SAndreas.Sandberg@arm.com * 20510913Sandreas.sandberg@arm.com * <li>Check if any object still needs draining 20610913Sandreas.sandberg@arm.com * (DrainManager::tryDrain()), if so repeat the process above. 2079342SAndreas.Sandberg@arm.com * 2089342SAndreas.Sandberg@arm.com * <li>Serialize objects, switch CPU model, or change timing model. 2099342SAndreas.Sandberg@arm.com * 21011002Sandreas.sandberg@arm.com * <li>Call DrainManager::resume(), which in turn calls 21111002Sandreas.sandberg@arm.com * Drainable::drainResume() for all objects, and then continue the 21210913Sandreas.sandberg@arm.com * simulation. 2139342SAndreas.Sandberg@arm.com * </ol> 2149342SAndreas.Sandberg@arm.com * 2159342SAndreas.Sandberg@arm.com */ 2169342SAndreas.Sandberg@arm.comclass Drainable 2179342SAndreas.Sandberg@arm.com{ 21810912Sandreas.sandberg@arm.com friend class DrainManager; 21910912Sandreas.sandberg@arm.com 22010913Sandreas.sandberg@arm.com protected: 2219342SAndreas.Sandberg@arm.com Drainable(); 2229342SAndreas.Sandberg@arm.com virtual ~Drainable(); 2239342SAndreas.Sandberg@arm.com 2249342SAndreas.Sandberg@arm.com /** 22511002Sandreas.sandberg@arm.com * Notify an object that it needs to drain its state. 2269342SAndreas.Sandberg@arm.com * 22710913Sandreas.sandberg@arm.com * If the object does not need further simulation to drain 22811002Sandreas.sandberg@arm.com * internal buffers, it returns DrainState::Drained and 22911002Sandreas.sandberg@arm.com * automatically switches to the Drained state. If the object 23011002Sandreas.sandberg@arm.com * needs more simulation, it returns DrainState::Draining and 23111002Sandreas.sandberg@arm.com * automatically enters the Draining state. Other return values 23211002Sandreas.sandberg@arm.com * are invalid. 2339342SAndreas.Sandberg@arm.com * 2349342SAndreas.Sandberg@arm.com * @note An object that has entered the Drained state can be 23511002Sandreas.sandberg@arm.com * disturbed by other objects in the system and consequently stop 23611002Sandreas.sandberg@arm.com * being drained. These perturbations are not visible in the drain 23711002Sandreas.sandberg@arm.com * state. The simulator therefore repeats the draining process 23811002Sandreas.sandberg@arm.com * until all objects return DrainState::Drained on the first call 23911002Sandreas.sandberg@arm.com * to drain(). 2409342SAndreas.Sandberg@arm.com * 24111002Sandreas.sandberg@arm.com * @return DrainState::Drained if the object is drained at this 24211002Sandreas.sandberg@arm.com * point in time, DrainState::Draining if it needs further 24310913Sandreas.sandberg@arm.com * simulation. 2449342SAndreas.Sandberg@arm.com */ 24510913Sandreas.sandberg@arm.com virtual DrainState drain() = 0; 2469342SAndreas.Sandberg@arm.com 2479342SAndreas.Sandberg@arm.com /** 2489342SAndreas.Sandberg@arm.com * Resume execution after a successful drain. 24910913Sandreas.sandberg@arm.com */ 25010913Sandreas.sandberg@arm.com virtual void drainResume() {}; 25110913Sandreas.sandberg@arm.com 25210913Sandreas.sandberg@arm.com /** 25310913Sandreas.sandberg@arm.com * Signal that an object is drained 2549342SAndreas.Sandberg@arm.com * 25510913Sandreas.sandberg@arm.com * This method is designed to be called whenever an object enters 25610913Sandreas.sandberg@arm.com * into a state where it is ready to be drained. The method is 25710913Sandreas.sandberg@arm.com * safe to call multiple times and there is no need to check that 25810913Sandreas.sandberg@arm.com * draining has been requested before calling this method. 2599342SAndreas.Sandberg@arm.com */ 26010913Sandreas.sandberg@arm.com void signalDrainDone() const { 26110913Sandreas.sandberg@arm.com switch (_drainState) { 26210913Sandreas.sandberg@arm.com case DrainState::Running: 26310913Sandreas.sandberg@arm.com case DrainState::Drained: 26410913Sandreas.sandberg@arm.com return; 26510913Sandreas.sandberg@arm.com case DrainState::Draining: 26610913Sandreas.sandberg@arm.com _drainState = DrainState::Drained; 26710913Sandreas.sandberg@arm.com _drainManager.signalDrainDone(); 26810913Sandreas.sandberg@arm.com return; 26910913Sandreas.sandberg@arm.com } 27010913Sandreas.sandberg@arm.com } 2719342SAndreas.Sandberg@arm.com 27210913Sandreas.sandberg@arm.com public: 27310913Sandreas.sandberg@arm.com /** Return the current drain state of an object. */ 27410913Sandreas.sandberg@arm.com DrainState drainState() const { return _drainState; } 2759342SAndreas.Sandberg@arm.com 27611360Sandreas@sandberg.pp.se /** 27711360Sandreas@sandberg.pp.se * Notify a child process of a fork. 27811360Sandreas@sandberg.pp.se * 27911360Sandreas@sandberg.pp.se * When calling fork in gem5, we need to ensure that resources 28011360Sandreas@sandberg.pp.se * shared between the parent and the child are consistent. This 28111360Sandreas@sandberg.pp.se * method is intended to be overloaded to handle that. For 28211360Sandreas@sandberg.pp.se * example, an object could use this method to re-open input files 28311360Sandreas@sandberg.pp.se * to get a separate file description with a private file offset. 28411360Sandreas@sandberg.pp.se * 28511360Sandreas@sandberg.pp.se * This method is only called in the child of the fork. The call 28611360Sandreas@sandberg.pp.se * takes place in a drained system. 28711360Sandreas@sandberg.pp.se */ 28811360Sandreas@sandberg.pp.se virtual void notifyFork() {}; 28911360Sandreas@sandberg.pp.se 2909342SAndreas.Sandberg@arm.com private: 29110913Sandreas.sandberg@arm.com /** DrainManager interface to request a drain operation */ 29210913Sandreas.sandberg@arm.com DrainState dmDrain(); 29310913Sandreas.sandberg@arm.com /** DrainManager interface to request a resume operation */ 29410913Sandreas.sandberg@arm.com void dmDrainResume(); 29510913Sandreas.sandberg@arm.com 29610913Sandreas.sandberg@arm.com /** Convenience reference to the drain manager */ 29710912Sandreas.sandberg@arm.com DrainManager &_drainManager; 29810913Sandreas.sandberg@arm.com 29910913Sandreas.sandberg@arm.com /** 30010913Sandreas.sandberg@arm.com * Current drain state of the object. Needs to be mutable since 30110913Sandreas.sandberg@arm.com * objects need to be able to signal that they have transitioned 30210913Sandreas.sandberg@arm.com * into a Drained state even if the calling method is const. 30310913Sandreas.sandberg@arm.com */ 30410913Sandreas.sandberg@arm.com mutable DrainState _drainState; 3059342SAndreas.Sandberg@arm.com}; 3069342SAndreas.Sandberg@arm.com 3079342SAndreas.Sandberg@arm.com#endif 308