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/*
* Copyright (c) 2011-2013 Advanced Micro Devices, Inc.
* Copyright (c) 2013 Mark D. Hill and David A. Wood
* 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: Steve Reinhardt
*/
#include "sim/global_event.hh"
std::mutex BaseGlobalEvent::globalQMutex;
BaseGlobalEvent::BaseGlobalEvent(Priority p, Flags f)
{
barrierEvent.resize(numMainEventQueues);
barrier = new Barrier(numMainEventQueues);
}
BaseGlobalEvent::~BaseGlobalEvent()
{
// see GlobalEvent::BarrierEvent::~BarrierEvent() comments
if (barrierEvent[0] != NULL) {
for (int i = 0; i < numMainEventQueues; ++i)
delete barrierEvent[i];
}
}
void BaseGlobalEvent::schedule(Tick when)
{
// This function is scheduling a global event, which actually is a
// set of local events, one event on each eventq. Global events need
// to have a total order. A thread cannot start executing events that
// follow a global event till all other threads have executed that global
// event as well. If global events were not in a total order, a deadlock
// would occur for there will be two threads who would be waiting for
// each other to execute the global events they themselves have executed.
//
// To ensure this total order, we do two things.
// First, before scheduling any global event, a thread needs to acquire
// the lock globalQMutex. This ensures that only one thread can schedule
// global events at any given time.
// Second, the local events corresponding to a global event are always
// first inserted in to the asyncq, irrespective of whether or not the
// thread scheduling the event owns the eventq on which the event is
// being scheduled. Thus global events have the same order in the asyncq
// of each thread. When they are inserted in the actual eventq, the
// comparators in the Event class ensure that the total order is
// maintained.
globalQMutex.lock();
for (int i = 0; i < numMainEventQueues; ++i) {
mainEventQueue[i]->schedule(barrierEvent[i], when, true);
}
globalQMutex.unlock();
}
void BaseGlobalEvent::deschedule()
{
EventQueue *q = curEventQueue();
for (uint32_t i = 0; i < numMainEventQueues; ++i) {
if (barrierEvent[i]->scheduled()) {
curEventQueue(mainEventQueue[i]);
mainEventQueue[i]->deschedule(barrierEvent[i]);
}
}
curEventQueue(q);
}
void BaseGlobalEvent::reschedule(Tick when)
{
// Read the comment in the schedule() function above.
globalQMutex.lock();
for (uint32_t i = 0; i < numMainEventQueues; ++i) {
if (barrierEvent[i]->scheduled())
mainEventQueue[i]->reschedule(barrierEvent[i], when);
else
mainEventQueue[i]->schedule(barrierEvent[i], when, true);
}
globalQMutex.unlock();
}
BaseGlobalEvent::BarrierEvent::~BarrierEvent()
{
// if AutoDelete is set, local events will get deleted in event
// loop, but we need to delete GlobalEvent object too... so let
// the local event in slot 0 do it
if (isFlagSet(AutoDelete) && _globalEvent->barrierEvent[0] == this) {
// set backpointer to NULL so that global event knows not to
// turn around and recursively delete local events
_globalEvent->barrierEvent[0] = NULL;
delete _globalEvent;
}
}
void
GlobalEvent::BarrierEvent::process()
{
// wait for all queues to arrive at barrier, then process event
if (globalBarrier()) {
_globalEvent->process();
}
// second barrier to force all queues to wait for event processing
// to finish before continuing
globalBarrier();
}
void
GlobalSyncEvent::BarrierEvent::process()
{
// wait for all queues to arrive at barrier, then process event
if (globalBarrier()) {
_globalEvent->process();
}
// second barrier to force all queues to wait for event processing
// to finish before continuing
globalBarrier();
curEventQueue()->handleAsyncInsertions();
}
void
GlobalSyncEvent::process()
{
if (repeat) {
schedule(curTick() + repeat);
}
}
const char *
GlobalSyncEvent::description() const
{
return "GlobalSyncEvent";
}
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