852a7bcf92
This patch adds a basic check to ensure that the packet queue does not grow absurdly large. The queue should only be used to store packets that were delayed due to blocking from the neighbouring port, and not for actual storage. Thus, a limit of 100 has been chosen for now (which is already quite substantial).
253 lines
8.0 KiB
C++
253 lines
8.0 KiB
C++
/*
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* Copyright (c) 2012 ARM Limited
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* All rights reserved.
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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*
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* Copyright (c) 2006 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Ali Saidi
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* Andreas Hansson
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*/
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#include "base/trace.hh"
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#include "debug/Drain.hh"
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#include "debug/PacketQueue.hh"
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#include "mem/packet_queue.hh"
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using namespace std;
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PacketQueue::PacketQueue(EventManager& _em, const std::string& _label)
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: em(_em), sendEvent(this), drainManager(NULL), label(_label),
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waitingOnRetry(false)
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{
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}
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PacketQueue::~PacketQueue()
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{
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}
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void
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PacketQueue::retry()
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{
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DPRINTF(PacketQueue, "Queue %s received retry\n", name());
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assert(waitingOnRetry);
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sendDeferredPacket();
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}
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bool
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PacketQueue::checkFunctional(PacketPtr pkt)
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{
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pkt->pushLabel(label);
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DeferredPacketIterator i = transmitList.begin();
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DeferredPacketIterator end = transmitList.end();
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bool found = false;
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while (!found && i != end) {
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// If the buffered packet contains data, and it overlaps the
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// current packet, then update data
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found = pkt->checkFunctional(i->pkt);
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++i;
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}
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pkt->popLabel();
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return found;
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}
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void
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PacketQueue::schedSendEvent(Tick when)
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{
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// if we are waiting on a retry, do not schedule a send event, and
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// instead rely on retry being called
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if (waitingOnRetry) {
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assert(!sendEvent.scheduled());
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return;
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}
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if (!sendEvent.scheduled()) {
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em.schedule(&sendEvent, when);
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} else if (sendEvent.when() > when) {
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em.reschedule(&sendEvent, when);
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}
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}
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void
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PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop)
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{
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// we can still send a packet before the end of this tick
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assert(when >= curTick());
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// express snoops should never be queued
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assert(!pkt->isExpressSnoop());
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// add a very basic sanity check on the port to ensure the
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// invisible buffer is not growing beyond reasonable limits
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if (transmitList.size() > 100) {
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panic("Packet queue %s has grown beyond 100 packets\n",
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name());
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}
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// nothing on the list, or earlier than current front element,
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// schedule an event
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if (transmitList.empty() || when < transmitList.front().tick) {
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// note that currently we ignore a potentially outstanding retry
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// and could in theory put a new packet at the head of the
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// transmit list before retrying the existing packet
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transmitList.push_front(DeferredPacket(when, pkt, send_as_snoop));
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schedSendEvent(when);
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return;
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}
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// list is non-empty and this belongs at the end
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if (when >= transmitList.back().tick) {
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transmitList.push_back(DeferredPacket(when, pkt, send_as_snoop));
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return;
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}
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// this belongs in the middle somewhere, insertion sort
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DeferredPacketIterator i = transmitList.begin();
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++i; // already checked for insertion at front
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while (i != transmitList.end() && when >= i->tick)
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++i;
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transmitList.insert(i, DeferredPacket(when, pkt, send_as_snoop));
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}
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void PacketQueue::trySendTiming()
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{
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assert(deferredPacketReady());
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// take the next packet off the list here, as we might return to
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// ourselves through the sendTiming call below
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DeferredPacket dp = transmitList.front();
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transmitList.pop_front();
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// use the appropriate implementation of sendTiming based on the
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// type of port associated with the queue, and whether the packet
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// is to be sent as a snoop or not
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waitingOnRetry = !sendTiming(dp.pkt, dp.sendAsSnoop);
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if (waitingOnRetry) {
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// put the packet back at the front of the list (packet should
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// not have changed since it wasn't accepted)
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assert(!sendEvent.scheduled());
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transmitList.push_front(dp);
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}
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}
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void
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PacketQueue::scheduleSend(Tick time)
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{
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// the next ready time is either determined by the next deferred packet,
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// or in the cache through the MSHR ready time
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Tick nextReady = std::min(deferredPacketReadyTime(), time);
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if (nextReady != MaxTick) {
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// if the sendTiming caused someone else to call our
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// recvTiming we could already have an event scheduled, check
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if (!sendEvent.scheduled())
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em.schedule(&sendEvent, std::max(nextReady, curTick() + 1));
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} else {
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// no more to send, so if we're draining, we may be done
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if (drainManager && transmitList.empty() && !sendEvent.scheduled()) {
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DPRINTF(Drain, "PacketQueue done draining,"
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"processing drain event\n");
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drainManager->signalDrainDone();
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drainManager = NULL;
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}
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}
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}
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void
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PacketQueue::sendDeferredPacket()
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{
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// try to send what is on the list, this will set waitingOnRetry
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// accordingly
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trySendTiming();
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// if we succeeded and are not waiting for a retry, schedule the
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// next send
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if (!waitingOnRetry) {
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scheduleSend();
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}
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}
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void
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PacketQueue::processSendEvent()
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{
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assert(!waitingOnRetry);
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sendDeferredPacket();
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}
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unsigned int
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PacketQueue::drain(DrainManager *dm)
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{
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if (transmitList.empty() && !sendEvent.scheduled())
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return 0;
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DPRINTF(Drain, "PacketQueue not drained\n");
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drainManager = dm;
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return 1;
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}
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MasterPacketQueue::MasterPacketQueue(EventManager& _em, MasterPort& _masterPort,
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const std::string _label)
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: PacketQueue(_em, _label), masterPort(_masterPort)
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{
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}
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bool
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MasterPacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
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{
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// attempt to send the packet and return according to the outcome
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if (!send_as_snoop)
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return masterPort.sendTimingReq(pkt);
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else
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return masterPort.sendTimingSnoopResp(pkt);
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}
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SlavePacketQueue::SlavePacketQueue(EventManager& _em, SlavePort& _slavePort,
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const std::string _label)
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: PacketQueue(_em, _label), slavePort(_slavePort)
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{
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}
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bool
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SlavePacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop)
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{
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// we should never have queued snoop requests
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assert(!send_as_snoop);
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return slavePort.sendTimingResp(pkt);
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}
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