gem5/src/sim/drain.cc

/*
 * Copyright (c) 2012, 2015 ARM Limited
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 *
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 * 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
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 *
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 * 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
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 *
 * Authors: Andreas Sandberg
 */

#include "sim/drain.hh"

#include "base/misc.hh"
#include "base/trace.hh"
#include "debug/Drain.hh"
#include "sim/sim_exit.hh"

DrainManager DrainManager::_instance;

DrainManager::DrainManager()
    : _count(0),
      _state(DrainState::Running)
{
}

DrainManager::~DrainManager()
{
}

bool
DrainManager::tryDrain()
{
    panic_if(_state == DrainState::Drained,
             "Trying to drain a drained system\n");

    panic_if(_count != 0,
             "Drain counter must be zero at the start of a drain cycle\n");

    DPRINTF(Drain, "Trying to drain %u objects.\n", drainableCount());
    _state = DrainState::Draining;
    for (auto *obj : _allDrainable)
        _count += obj->dmDrain() == DrainState::Drained ? 0 : 1;

    if (_count == 0) {
        DPRINTF(Drain, "Drain done.\n");
        _state = DrainState::Drained;
        return true;
    } else {
        DPRINTF(Drain, "Need another drain cycle. %u/%u objects not ready.\n",
                _count, drainableCount());
        return false;
    }
}

void
DrainManager::resume()
{
    panic_if(_state == DrainState::Running,
             "Trying to resume a system that is already running\n");

    warn_if(_state == DrainState::Draining,
            "Resuming a system that isn't fully drained, this is untested and "
            "likely to break\n");

    panic_if(_count != 0,
             "Resume called in the middle of a drain cycle. %u objects "
             "left to drain.\n", _count);

    DPRINTF(Drain, "Resuming %u objects.\n", drainableCount());
    _state = DrainState::Running;
    for (auto *obj : _allDrainable)
        obj->dmDrainResume();
}

void
DrainManager::preCheckpointRestore()
{
    panic_if(_state != DrainState::Running,
             "preCheckpointRestore() called on a system that isn't in the "
             "Running state.\n");

    DPRINTF(Drain, "Applying pre-restore fixes to %u objects.\n",
            drainableCount());
    _state = DrainState::Drained;
    for (auto *obj : _allDrainable)
        obj->_drainState = DrainState::Drained;
}

void
DrainManager::signalDrainDone()
{
    if (--_count == 0) {
        DPRINTF(Drain, "All %u objects drained..\n", drainableCount());
        exitSimLoop("Finished drain", 0);
    }
}


void
DrainManager::registerDrainable(Drainable *obj)
{
    std::lock_guard<std::mutex> lock(globalLock);
    _allDrainable.insert(obj);
}

void
DrainManager::unregisterDrainable(Drainable *obj)
{
    std::lock_guard<std::mutex> lock(globalLock);
    _allDrainable.erase(obj);
}

size_t
DrainManager::drainableCount() const
{
    std::lock_guard<std::mutex> lock(globalLock);
    return _allDrainable.size();
}



Drainable::Drainable()
    : _drainManager(DrainManager::instance()),
      _drainState(_drainManager.state())
{
    _drainManager.registerDrainable(this);
}

Drainable::~Drainable()
{
    _drainManager.unregisterDrainable(this);
}

DrainState
Drainable::dmDrain()
{
    _drainState = DrainState::Draining;
    _drainState = drain();
    assert(_drainState == DrainState::Draining ||
           _drainState == DrainState::Drained);

    return _drainState;
}

void
Drainable::dmDrainResume()
{
    panic_if(_drainState != DrainState::Drained,
             "Trying to resume an object that hasn't been drained\n");

    _drainState = DrainState::Running;
    drainResume();
}