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/*
* Copyright (c) 2012,2015,2018 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.
*
* Copyright (c) 2006 The Regents of The University of Michigan
* 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: Ali Saidi
* Andreas Hansson
*/
#include "mem/packet_queue.hh"
#include "base/trace.hh"
#include "debug/Drain.hh"
#include "debug/PacketQueue.hh"
PacketQueue::PacketQueue(EventManager& _em, const std::string& _label,
const std::string& _sendEventName,
bool force_order,
bool disable_sanity_check)
: em(_em), sendEvent([this]{ processSendEvent(); }, _sendEventName),
_disableSanityCheck(disable_sanity_check),
forceOrder(force_order),
label(_label), waitingOnRetry(false)
{
}
PacketQueue::~PacketQueue()
{
}
void
PacketQueue::retry()
{
DPRINTF(PacketQueue, "Queue %s received retry\n", name());
assert(waitingOnRetry);
waitingOnRetry = false;
sendDeferredPacket();
}
bool
PacketQueue::hasAddr(Addr addr) const
{
// caller is responsible for ensuring that all packets have the
// same alignment
for (const auto& p : transmitList) {
if (p.pkt->getAddr() == addr)
return true;
}
return false;
}
bool
PacketQueue::trySatisfyFunctional(PacketPtr pkt)
{
pkt->pushLabel(label);
auto i = transmitList.begin();
bool found = false;
while (!found && i != transmitList.end()) {
// If the buffered packet contains data, and it overlaps the
// current packet, then update data
found = pkt->trySatisfyFunctional(i->pkt);
++i;
}
pkt->popLabel();
return found;
}
void
PacketQueue::schedSendTiming(PacketPtr pkt, Tick when)
{
DPRINTF(PacketQueue, "%s for %s address %x size %d when %lu ord: %i\n",
__func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(), when,
forceOrder);
// we can still send a packet before the end of this tick
assert(when >= curTick());
// express snoops should never be queued
assert(!pkt->isExpressSnoop());
// add a very basic sanity check on the port to ensure the
// invisible buffer is not growing beyond reasonable limits
if (!_disableSanityCheck && transmitList.size() > 100) {
panic("Packet queue %s has grown beyond 100 packets\n",
name());
}
// we should either have an outstanding retry, or a send event
// scheduled, but there is an unfortunate corner case where the
// x86 page-table walker and timing CPU send out a new request as
// part of the receiving of a response (called by
// PacketQueue::sendDeferredPacket), in which we end up calling
// ourselves again before we had a chance to update waitingOnRetry
// assert(waitingOnRetry || sendEvent.scheduled());
// this belongs in the middle somewhere, so search from the end to
// order by tick; however, if forceOrder is set, also make sure
// not to re-order in front of some existing packet with the same
// address
auto it = transmitList.end();
while (it != transmitList.begin()) {
--it;
if ((forceOrder && it->pkt->getAddr() == pkt->getAddr()) ||
it->tick <= when) {
// emplace inserts the element before the position pointed to by
// the iterator, so advance it one step
transmitList.emplace(++it, when, pkt);
return;
}
}
// either the packet list is empty or this has to be inserted
// before every other packet
transmitList.emplace_front(when, pkt);
schedSendEvent(when);
}
void
PacketQueue::schedSendEvent(Tick when)
{
// if we are waiting on a retry just hold off
if (waitingOnRetry) {
DPRINTF(PacketQueue, "Not scheduling send as waiting for retry\n");
assert(!sendEvent.scheduled());
return;
}
if (when != MaxTick) {
// we cannot go back in time, and to be consistent we stick to
// one tick in the future
when = std::max(when, curTick() + 1);
// @todo Revisit the +1
if (!sendEvent.scheduled()) {
em.schedule(&sendEvent, when);
} else if (when < sendEvent.when()) {
// if the new time is earlier than when the event
// currently is scheduled, move it forward
em.reschedule(&sendEvent, when);
}
} else {
// we get a MaxTick when there is no more to send, so if we're
// draining, we may be done at this point
if (drainState() == DrainState::Draining &&
transmitList.empty() && !sendEvent.scheduled()) {
DPRINTF(Drain, "PacketQueue done draining,"
"processing drain event\n");
signalDrainDone();
}
}
}
void
PacketQueue::sendDeferredPacket()
{
// sanity checks
assert(!waitingOnRetry);
assert(deferredPacketReady());
DeferredPacket dp = transmitList.front();
// take the packet of the list before sending it, as sending of
// the packet in some cases causes a new packet to be enqueued
// (most notaly when responding to the timing CPU, leading to a
// new request hitting in the L1 icache, leading to a new
// response)
transmitList.pop_front();
// use the appropriate implementation of sendTiming based on the
// type of queue
waitingOnRetry = !sendTiming(dp.pkt);
// if we succeeded and are not waiting for a retry, schedule the
// next send
if (!waitingOnRetry) {
schedSendEvent(deferredPacketReadyTime());
} else {
// put the packet back at the front of the list
transmitList.emplace_front(dp);
}
}
void
PacketQueue::processSendEvent()
{
assert(!waitingOnRetry);
sendDeferredPacket();
}
DrainState
PacketQueue::drain()
{
if (transmitList.empty()) {
return DrainState::Drained;
} else {
DPRINTF(Drain, "PacketQueue not drained\n");
return DrainState::Draining;
}
}
ReqPacketQueue::ReqPacketQueue(EventManager& _em, MasterPort& _masterPort,
const std::string _label)
: PacketQueue(_em, _label, name(_masterPort, _label)),
masterPort(_masterPort)
{
}
bool
ReqPacketQueue::sendTiming(PacketPtr pkt)
{
return masterPort.sendTimingReq(pkt);
}
SnoopRespPacketQueue::SnoopRespPacketQueue(EventManager& _em,
MasterPort& _masterPort,
bool force_order,
const std::string _label)
: PacketQueue(_em, _label, name(_masterPort, _label), force_order),
masterPort(_masterPort)
{
}
bool
SnoopRespPacketQueue::sendTiming(PacketPtr pkt)
{
return masterPort.sendTimingSnoopResp(pkt);
}
RespPacketQueue::RespPacketQueue(EventManager& _em, SlavePort& _slavePort,
bool force_order,
const std::string _label)
: PacketQueue(_em, _label, name(_slavePort, _label), force_order),
slavePort(_slavePort)
{
}
bool
RespPacketQueue::sendTiming(PacketPtr pkt)
{
return slavePort.sendTimingResp(pkt);
}