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/*
* Copyright (c) 2002-2005 The Regents of The University of Michigan
* Copyright (c) 2011 Advanced Micro Devices, Inc.
* 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: Nathan Binkert
* Steve Reinhardt
* Gabe Black
*/
#include "base/misc.hh"
#include "debug/TimeSync.hh"
#include "sim/root.hh"
Root *Root::_root = NULL;
/*
* This function is called periodically by an event in M5 and ensures that
* at least as much real time has passed between invocations as simulated time.
* If not, the function either sleeps, or if the difference is small enough
* spin waits.
*/
void
Root::timeSync()
{
Time cur_time, diff, period = timeSyncPeriod();
do {
cur_time.setTimer();
diff = cur_time - lastTime;
Time remainder = period - diff;
if (diff < period && remainder > _spinThreshold) {
DPRINTF(TimeSync, "Sleeping to sync with real time.\n");
// Sleep until the end of the period, or until a signal.
sleep(remainder);
// Refresh the current time.
cur_time.setTimer();
}
} while (diff < period);
lastTime = cur_time;
schedule(&syncEvent, curTick() + _periodTick);
}
void
Root::timeSyncEnable(bool en)
{
if (en == _enabled)
return;
_enabled = en;
if (_enabled) {
// Get event going.
Tick periods = ((curTick() + _periodTick - 1) / _periodTick);
Tick nextPeriod = periods * _periodTick;
schedule(&syncEvent, nextPeriod);
} else {
// Stop event.
deschedule(&syncEvent);
}
}
/// Configure the period for time sync events.
void
Root::timeSyncPeriod(Time newPeriod)
{
bool en = timeSyncEnabled();
_period = newPeriod;
_periodTick = _period.getTick();
timeSyncEnable(en);
}
/// Set the threshold for time remaining to spin wait.
void
Root::timeSyncSpinThreshold(Time newThreshold)
{
bool en = timeSyncEnabled();
_spinThreshold = newThreshold;
timeSyncEnable(en);
}
Root::Root(RootParams *p) : SimObject(p), _enabled(false),
_periodTick(p->time_sync_period), syncEvent(this)
{
_period.setTick(p->time_sync_period);
_spinThreshold.setTick(p->time_sync_spin_threshold);
assert(_root == NULL);
_root = this;
lastTime.setTimer();
}
void
Root::initState()
{
timeSyncEnable(params()->time_sync_enable);
}
void
Root::loadState(Checkpoint *cp)
{
timeSyncEnable(params()->time_sync_enable);
}
Root *
RootParams::create()
{
static bool created = false;
if (created)
panic("only one root object allowed!");
created = true;
return new Root(this);
}
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