diff options
Diffstat (limited to 'src/mem/packet_queue.cc')
-rw-r--r-- | src/mem/packet_queue.cc | 151 |
1 files changed, 84 insertions, 67 deletions
diff --git a/src/mem/packet_queue.cc b/src/mem/packet_queue.cc index e9fe72ead..29f6d2903 100644 --- a/src/mem/packet_queue.cc +++ b/src/mem/packet_queue.cc @@ -1,5 +1,5 @@ /* - * Copyright (c) 2012 ARM Limited + * Copyright (c) 2012,2015 ARM Limited * All rights reserved. * * The license below extends only to copyright in the software and shall @@ -63,10 +63,23 @@ 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::checkFunctional(PacketPtr pkt) { pkt->pushLabel(label); @@ -87,27 +100,11 @@ PacketQueue::checkFunctional(PacketPtr pkt) } void -PacketQueue::schedSendEvent(Tick when) -{ - // if we are waiting on a retry, do not schedule a send event, and - // instead rely on retry being called - if (waitingOnRetry) { - assert(!sendEvent.scheduled()); - return; - } - - if (!sendEvent.scheduled()) { - em.schedule(&sendEvent, when); - } else if (sendEvent.when() > when) { - em.reschedule(&sendEvent, when); - } -} - -void -PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop) +PacketQueue::schedSendTiming(PacketPtr pkt, Tick when) { DPRINTF(PacketQueue, "%s for %s address %x size %d\n", __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize()); + // we can still send a packet before the end of this tick assert(when >= curTick()); @@ -127,14 +124,22 @@ PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop) // note that currently we ignore a potentially outstanding retry // and could in theory put a new packet at the head of the // transmit list before retrying the existing packet - transmitList.push_front(DeferredPacket(when, pkt, send_as_snoop)); + transmitList.push_front(DeferredPacket(when, pkt)); schedSendEvent(when); return; } + // 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()); + // list is non-empty and this belongs at the end if (when >= transmitList.back().tick) { - transmitList.push_back(DeferredPacket(when, pkt, send_as_snoop)); + transmitList.push_back(DeferredPacket(when, pkt)); return; } @@ -143,46 +148,35 @@ PacketQueue::schedSendTiming(PacketPtr pkt, Tick when, bool send_as_snoop) ++i; // already checked for insertion at front while (i != transmitList.end() && when >= i->tick) ++i; - transmitList.insert(i, DeferredPacket(when, pkt, send_as_snoop)); + transmitList.insert(i, DeferredPacket(when, pkt)); } -void PacketQueue::trySendTiming() +void +PacketQueue::schedSendEvent(Tick when) { - assert(deferredPacketReady()); - - DeferredPacket dp = transmitList.front(); - - // use the appropriate implementation of sendTiming based on the - // type of port associated with the queue, and whether the packet - // is to be sent as a snoop or not - waitingOnRetry = !sendTiming(dp.pkt, dp.sendAsSnoop); - - if (!waitingOnRetry) { - // take the packet off the list - transmitList.pop_front(); + // 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; } -} -void -PacketQueue::scheduleSend(Tick time) -{ - // the next ready time is either determined by the next deferred packet, - // or in the cache through the MSHR ready time - Tick nextReady = std::max(std::min(deferredPacketReadyTime(), time), - curTick() + 1); + 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 (nextReady != MaxTick) { - // if the sendTiming caused someone else to call our - // recvTiming we could already have an event scheduled, check if (!sendEvent.scheduled()) { - em.schedule(&sendEvent, nextReady); - } else if (nextReady < sendEvent.when()) { + 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, nextReady); + em.reschedule(&sendEvent, when); } } else { - // no more to send, so if we're draining, we may be done + // we get a MaxTick when there is no more to send, so if we're + // draining, we may be done at this point if (drainManager && transmitList.empty() && !sendEvent.scheduled()) { DPRINTF(Drain, "PacketQueue done draining," "processing drain event\n"); @@ -195,14 +189,30 @@ PacketQueue::scheduleSend(Tick time) void PacketQueue::sendDeferredPacket() { - // try to send what is on the list, this will set waitingOnRetry - // accordingly - trySendTiming(); + // 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) { - scheduleSend(); + schedSendEvent(deferredPacketReadyTime()); + } else { + // put the packet back at the front of the list + transmitList.push_front(dp); } } @@ -223,32 +233,39 @@ PacketQueue::drain(DrainManager *dm) return 1; } -MasterPacketQueue::MasterPacketQueue(EventManager& _em, MasterPort& _masterPort, - const std::string _label) +ReqPacketQueue::ReqPacketQueue(EventManager& _em, MasterPort& _masterPort, + const std::string _label) + : PacketQueue(_em, _label), masterPort(_masterPort) +{ +} + +bool +ReqPacketQueue::sendTiming(PacketPtr pkt) +{ + return masterPort.sendTimingReq(pkt); +} + +SnoopRespPacketQueue::SnoopRespPacketQueue(EventManager& _em, + MasterPort& _masterPort, + const std::string _label) : PacketQueue(_em, _label), masterPort(_masterPort) { } bool -MasterPacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop) +SnoopRespPacketQueue::sendTiming(PacketPtr pkt) { - // attempt to send the packet and return according to the outcome - if (!send_as_snoop) - return masterPort.sendTimingReq(pkt); - else - return masterPort.sendTimingSnoopResp(pkt); + return masterPort.sendTimingSnoopResp(pkt); } -SlavePacketQueue::SlavePacketQueue(EventManager& _em, SlavePort& _slavePort, - const std::string _label) +RespPacketQueue::RespPacketQueue(EventManager& _em, SlavePort& _slavePort, + const std::string _label) : PacketQueue(_em, _label), slavePort(_slavePort) { } bool -SlavePacketQueue::sendTiming(PacketPtr pkt, bool send_as_snoop) +RespPacketQueue::sendTiming(PacketPtr pkt) { - // we should never have queued snoop requests - assert(!send_as_snoop); return slavePort.sendTimingResp(pkt); } |