diff options
Diffstat (limited to 'src/mem/bus.cc')
| -rw-r--r-- | src/mem/bus.cc | 502 |
1 files changed, 319 insertions, 183 deletions
diff --git a/src/mem/bus.cc b/src/mem/bus.cc index c89455f02..eb26e268b 100644 --- a/src/mem/bus.cc +++ b/src/mem/bus.cc @@ -57,7 +57,6 @@ Bus::Bus(const BusParams *p) : MemObject(p), clock(p->clock), headerCycles(p->header_cycles), width(p->width), tickNextIdle(0), drainEvent(NULL), busIdleEvent(this), inRetry(false), - nbrMasterPorts(p->port_master_connection_count), defaultPortId(INVALID_PORT_ID), useDefaultRange(p->use_default_range), defaultBlockSize(p->block_size), cachedBlockSize(0), cachedBlockSizeValid(false) @@ -71,40 +70,28 @@ Bus::Bus(const BusParams *p) fatal("Number of header cycles must be positive\n"); // create the ports based on the size of the master and slave - // vector ports, and the presence of the default master - - // id used to index into master and slave ports, that currently - // has holes to be able to use the id to index into either - int id = 0; + // vector ports, and the presence of the default port, the ports + // are enumerated starting from zero for (int i = 0; i < p->port_master_connection_count; ++i) { - std::string portName = csprintf("%s-p%d", name(), id); - BusMasterPort* bp = new BusMasterPort(portName, this, id); + std::string portName = csprintf("%s-p%d", name(), i); + BusMasterPort* bp = new BusMasterPort(portName, this, i); masterPorts.push_back(bp); - slavePorts.push_back(NULL); - ++id; } - // see if we have a default master connected and if so add the - // port + // see if we have a default slave device connected and if so add + // our corresponding master port if (p->port_default_connection_count) { - defaultPortId = id; + defaultPortId = masterPorts.size(); std::string portName = csprintf("%s-default", name()); - BusMasterPort* bp = new BusMasterPort(portName, this, id); + BusMasterPort* bp = new BusMasterPort(portName, this, defaultPortId); masterPorts.push_back(bp); - slavePorts.push_back(NULL); - ++id; - // this is an additional master port - ++nbrMasterPorts; } - // note that the first slave port is now stored on index - // nbrMasterPorts in the vector + // create the slave ports, once again starting at zero for (int i = 0; i < p->port_slave_connection_count; ++i) { - std::string portName = csprintf("%s-p%d", name(), id); - BusSlavePort* bp = new BusSlavePort(portName, this, id); - masterPorts.push_back(NULL); + std::string portName = csprintf("%s-p%d", name(), i); + BusSlavePort* bp = new BusSlavePort(portName, this, i); slavePorts.push_back(bp); - ++id; } clearPortCache(); @@ -113,9 +100,8 @@ Bus::Bus(const BusParams *p) MasterPort & Bus::getMasterPort(const std::string &if_name, int idx) { - if (if_name == "master") { - // the master index translates directly to the interfaces - // vector as they are stored first + if (if_name == "master" && idx < masterPorts.size()) { + // the master port index translates directly to the vector position return *masterPorts[idx]; } else if (if_name == "default") { return *masterPorts[defaultPortId]; @@ -127,8 +113,9 @@ Bus::getMasterPort(const std::string &if_name, int idx) SlavePort & Bus::getSlavePort(const std::string &if_name, int idx) { - if (if_name == "slave") { - return *slavePorts[nbrMasterPorts + idx]; + if (if_name == "slave" && idx < slavePorts.size()) { + // the slave port index translates directly to the vector position + return *slavePorts[idx]; } else { return MemObject::getSlavePort(if_name, idx); } @@ -137,19 +124,15 @@ Bus::getSlavePort(const std::string &if_name, int idx) void Bus::init() { - std::vector<BusSlavePort*>::iterator intIter; - - // iterate over our interfaces and determine which of our neighbours - // are snooping and add them as snoopers - for (intIter = slavePorts.begin(); intIter != slavePorts.end(); - intIter++) { - // since there are holes in the vector, check for NULL - if (*intIter != NULL) { - if ((*intIter)->getMasterPort().isSnooping()) { - DPRINTF(BusAddrRanges, "Adding snooping neighbour %s\n", - (*intIter)->getMasterPort().name()); - snoopPorts.push_back(*intIter); - } + std::vector<BusSlavePort*>::iterator p; + + // iterate over our slave ports and determine which of our + // neighbouring master ports are snooping and add them as snoopers + for (p = slavePorts.begin(); p != slavePorts.end(); ++p) { + if ((*p)->getMasterPort().isSnooping()) { + DPRINTF(BusAddrRanges, "Adding snooping neighbour %s\n", + (*p)->getMasterPort().name()); + snoopPorts.push_back(*p); } } } @@ -200,27 +183,36 @@ void Bus::occupyBus(Tick until) curTick(), tickNextIdle); } -/** Function called by the port when the bus is receiving a Timing - * transaction.*/ bool -Bus::recvTiming(PacketPtr pkt) +Bus::isOccupied(PacketPtr pkt, Port* port) { - // called for both requests and responses + // first we see if the next idle tick is in the future, next the + // bus is considered occupied if there are ports on the retry list + // and we are not in a retry with the current port + if (tickNextIdle > curTick() || + (!retryList.empty() && !(inRetry && port == retryList.front()))) { + addToRetryList(port); + return true; + } + return false; +} - // get the source id and port +bool +Bus::recvTiming(PacketPtr pkt) +{ + // get the source id Packet::NodeID src_id = pkt->getSrc(); - // determine the source port based on the id - Port *src_port = slavePorts[src_id] ? - (Port*) slavePorts[src_id] : (Port*) masterPorts[src_id]; - - // If the bus is busy, or other devices are in line ahead of the current - // one, put this device on the retry list. - if (!pkt->isExpressSnoop() && - (tickNextIdle > curTick() || - (!retryList.empty() && (!inRetry || src_port != retryList.front())))) - { - addToRetryList(src_port); + // determine the source port based on the id and direction + Port *src_port = NULL; + if (pkt->isRequest()) + src_port = slavePorts[src_id]; + else + src_port = masterPorts[src_id]; + + // test if the bus should be considered occupied for the current + // packet, and exclude express snoops from the check + if (!pkt->isExpressSnoop() && isOccupied(pkt, src_port)) { DPRINTF(Bus, "recvTiming: src %d dst %d %s 0x%x BUSY\n", src_id, pkt->getDest(), pkt->cmdString(), pkt->getAddr()); return false; @@ -232,89 +224,196 @@ Bus::recvTiming(PacketPtr pkt) Tick headerFinishTime = pkt->isExpressSnoop() ? 0 : calcPacketTiming(pkt); Tick packetFinishTime = pkt->isExpressSnoop() ? 0 : pkt->finishTime; - Packet::NodeID dest = pkt->getDest(); - int dest_id; - Port *dest_port; - + // decide what to do based on the direction if (pkt->isRequest()) { // the packet is a memory-mapped request and should be broadcasted to // our snoopers - assert(dest == Packet::Broadcast); - - SnoopIter s_end = snoopPorts.end(); - for (SnoopIter s_iter = snoopPorts.begin(); s_iter != s_end; s_iter++) { - BusSlavePort *p = *s_iter; - // we got this request from a snooping master - // (corresponding to our own slave port that is also in - // snoopPorts) and should not send it back to where it - // came from - if (p->getId() != src_id) { - // cache is not allowed to refuse snoop - bool success M5_VAR_USED = p->sendTiming(pkt); - assert(success); - } + assert(pkt->getDest() == Packet::Broadcast); + + // forward to all snoopers but the source + forwardTiming(pkt, src_id); + + // remember if we add an outstanding req so we can undo it if + // necessary, if the packet needs a response, we should add it + // as outstanding and express snoops never fail so there is + // not need to worry about them + bool add_outstanding = !pkt->isExpressSnoop() && pkt->needsResponse(); + + // keep track that we have an outstanding request packet + // matching this request, this is used by the coherency + // mechanism in determining what to do with snoop responses + // (in recvTimingSnoop) + if (add_outstanding) { + // we should never have an exsiting request outstanding + assert(outstandingReq.find(pkt->req) == outstandingReq.end()); + outstandingReq.insert(pkt->req); } - // since it is a request, similar to functional and atomic, - // determine the destination based on the address and forward - // through the corresponding master port - dest_id = findPort(pkt->getAddr()); - dest_port = masterPorts[dest_id]; - } else { - // the packet is a response, and it should always go back to - // the port determined by the destination field - dest_id = dest; - assert(dest_id != src_id); // catch infinite loops - dest_port = slavePorts[dest_id] ? - (Port*) slavePorts[dest_id] : (Port*) masterPorts[dest_id]; - - // a normal response from the memory system (i.e. from a - // connected slave) should always go back to the master - // that issued it through one of our slave ports, however - // if this is a snoop response it could go either way, for - // example, it could be coming from a slave port - // connecting an L1 with a coherent master and another L1 - // coherent master (one of our slave ports), or coming - // from the L1 and going to the L2 slave port (through one - // of our master ports) - } - - assert(dest_port != NULL); - - // if this is a snoop from a slave (corresponding to our own - // master), i.e. the memory side of the bus, then do not send it - // back to where it came from - if (dest_id != src_id) { - // send to actual target - if (!dest_port->sendTiming(pkt)) { - // Packet not successfully sent. Leave or put it on the retry list. - // illegal to block responses... can lead to deadlock - assert(!pkt->isResponse()); - // It's also illegal to force a transaction to retry after - // someone else has committed to respond. + // since it is a normal request, determine the destination + // based on the address and attempt to send the packet + bool success = masterPorts[findPort(pkt->getAddr())]->sendTiming(pkt); + + if (!success) { + // inhibited packets should never be forced to retry assert(!pkt->memInhibitAsserted()); - DPRINTF(Bus, "recvTiming: src %d dst %d %s 0x%x TGT RETRY\n", + + // if it was added as outstanding and the send failed, then + // erase it again + if (add_outstanding) + outstandingReq.erase(pkt->req); + + DPRINTF(Bus, "recvTiming: src %d dst %d %s 0x%x RETRY\n", src_id, pkt->getDest(), pkt->cmdString(), pkt->getAddr()); + addToRetryList(src_port); occupyBus(headerFinishTime); + return false; } - // send OK, fall through... pkt may have been deleted by - // target at this point, so it should *not* be referenced - // again. We'll set it to NULL here just to be safe. - pkt = NULL; + } else { + // the packet is a normal response to a request that we should + // have seen passing through the bus + assert(outstandingReq.find(pkt->req) != outstandingReq.end()); + + // remove it as outstanding + outstandingReq.erase(pkt->req); + + // send the packet to the destination through one of our slave + // ports, as determined by the destination field + bool success M5_VAR_USED = slavePorts[pkt->getDest()]->sendTiming(pkt); + + // currently it is illegal to block responses... can lead to + // deadlock + assert(success); } - occupyBus(packetFinishTime); + succeededTiming(packetFinishTime); + + return true; +} + +bool +Bus::recvTimingSnoop(PacketPtr pkt) +{ + // get the source id + Packet::NodeID src_id = pkt->getSrc(); + + if (pkt->isRequest()) { + DPRINTF(Bus, "recvTimingSnoop: src %d dst %d %s 0x%x\n", + src_id, pkt->getDest(), pkt->cmdString(), pkt->getAddr()); + + // the packet is an express snoop request and should be + // broadcasted to our snoopers + assert(pkt->getDest() == Packet::Broadcast); + assert(pkt->isExpressSnoop()); + + // forward to all snoopers + forwardTiming(pkt, INVALID_PORT_ID); + + // a snoop request came from a connected slave device (one of + // our master ports), and if it is not coming from the slave + // device responsible for the address range something is + // wrong, hence there is nothing further to do as the packet + // would be going back to where it came from + assert(src_id == findPort(pkt->getAddr())); + + // this is an express snoop and is never forced to retry + assert(!inRetry); + + return true; + } else { + // determine the source port based on the id + SlavePort* src_port = slavePorts[src_id]; - // Packet was successfully sent. - // Also take care of retries + if (isOccupied(pkt, src_port)) { + DPRINTF(Bus, "recvTimingSnoop: src %d dst %d %s 0x%x BUSY\n", + src_id, pkt->getDest(), pkt->cmdString(), pkt->getAddr()); + return false; + } + + DPRINTF(Bus, "recvTimingSnoop: src %d dst %d %s 0x%x\n", + src_id, pkt->getDest(), pkt->cmdString(), pkt->getAddr()); + + // get the destination from the packet + Packet::NodeID dest = pkt->getDest(); + + // responses are never express snoops + assert(!pkt->isExpressSnoop()); + + calcPacketTiming(pkt); + Tick packetFinishTime = pkt->finishTime; + + // determine if the response is from a snoop request we + // created as the result of a normal request (in which case it + // should be in the outstandingReq), or if we merely forwarded + // someone else's snoop request + if (outstandingReq.find(pkt->req) == outstandingReq.end()) { + // this is a snoop response to a snoop request we + // forwarded, e.g. coming from the L1 and going to the L2 + // this should be forwarded as a snoop response + bool success M5_VAR_USED = masterPorts[dest]->sendTimingSnoop(pkt); + assert(success); + } else { + // we got a snoop response on one of our slave ports, + // i.e. from a coherent master connected to the bus, and + // since we created the snoop request as part of + // recvTiming, this should now be a normal response again + outstandingReq.erase(pkt->req); + + // this is a snoop response from a coherent master, with a + // destination field set on its way through the bus as + // request, hence it should never go back to where the + // snoop response came from, but instead to where the + // original request came from + assert(src_id != dest); + + // as a normal response, it should go back to a master + // through one of our slave ports + bool success M5_VAR_USED = slavePorts[dest]->sendTiming(pkt); + + // currently it is illegal to block responses... can lead + // to deadlock + assert(success); + } + + succeededTiming(packetFinishTime); + + return true; + } +} + +void +Bus::succeededTiming(Tick busy_time) +{ + // occupy the bus accordingly + occupyBus(busy_time); + + // if a retrying port succeeded, also take it off the retry list if (inRetry) { - DPRINTF(Bus, "Remove retry from list %d\n", src_id); + DPRINTF(Bus, "Remove retry from list %s\n", + retryList.front()->name()); retryList.pop_front(); inRetry = false; } - return true; +} + +void +Bus::forwardTiming(PacketPtr pkt, int exclude_slave_port_id) +{ + SnoopIter s_end = snoopPorts.end(); + for (SnoopIter s_iter = snoopPorts.begin(); s_iter != s_end; s_iter++) { + BusSlavePort *p = *s_iter; + // we could have gotten this request from a snooping master + // (corresponding to our own slave port that is also in + // snoopPorts) and should not send it back to where it came + // from + if (exclude_slave_port_id == INVALID_PORT_ID || + p->getId() != exclude_slave_port_id) { + // cache is not allowed to refuse snoop + bool success M5_VAR_USED = p->sendTimingSnoop(pkt); + assert(success); + } + } } void @@ -430,9 +529,6 @@ Bus::findPort(Addr addr) name()); } - -/** Function called by the port when the bus is receiving a Atomic - * transaction.*/ Tick Bus::recvAtomic(PacketPtr pkt) { @@ -443,12 +539,59 @@ Bus::recvAtomic(PacketPtr pkt) assert(pkt->getDest() == Packet::Broadcast); assert(pkt->isRequest()); - // the packet may be changed by another bus on snoops, record the - // source id here - Packet::NodeID src_id = pkt->getSrc(); + // forward to all snoopers but the source + std::pair<MemCmd, Tick> snoop_result = forwardAtomic(pkt, pkt->getSrc()); + MemCmd snoop_response_cmd = snoop_result.first; + Tick snoop_response_latency = snoop_result.second; - // record the original command to enable us to restore it between - // snoops so that additional snoops can take place properly + // even if we had a snoop response, we must continue and also + // perform the actual request at the destination + int dest_id = findPort(pkt->getAddr()); + + // forward the request to the appropriate destination + Tick response_latency = masterPorts[dest_id]->sendAtomic(pkt); + + // if we got a response from a snooper, restore it here + if (snoop_response_cmd != MemCmd::InvalidCmd) { + // no one else should have responded + assert(!pkt->isResponse()); + pkt->cmd = snoop_response_cmd; + response_latency = snoop_response_latency; + } + + pkt->finishTime = curTick() + response_latency; + return response_latency; +} + +Tick +Bus::recvAtomicSnoop(PacketPtr pkt) +{ + DPRINTF(Bus, "recvAtomicSnoop: packet src %d dest %d addr 0x%x cmd %s\n", + pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString()); + + // we should always see a request routed based on the address + assert(pkt->getDest() == Packet::Broadcast); + assert(pkt->isRequest()); + + // forward to all snoopers + std::pair<MemCmd, Tick> snoop_result = forwardAtomic(pkt, INVALID_PORT_ID); + MemCmd snoop_response_cmd = snoop_result.first; + Tick snoop_response_latency = snoop_result.second; + + if (snoop_response_cmd != MemCmd::InvalidCmd) + pkt->cmd = snoop_response_cmd; + + pkt->finishTime = curTick() + snoop_response_latency; + return snoop_response_latency; +} + +std::pair<MemCmd, Tick> +Bus::forwardAtomic(PacketPtr pkt, int exclude_slave_port_id) +{ + // the packet may be changed on snoops, record the original source + // and command to enable us to restore it between snoops so that + // additional snoops can take place properly + Packet::NodeID orig_src_id = pkt->getSrc(); MemCmd orig_cmd = pkt->cmd; MemCmd snoop_response_cmd = MemCmd::InvalidCmd; Tick snoop_response_latency = 0; @@ -460,8 +603,9 @@ Bus::recvAtomic(PacketPtr pkt) // (corresponding to our own slave port that is also in // snoopPorts) and should not send it back to where it came // from - if (p->getId() != src_id) { - Tick latency = p->sendAtomic(pkt); + if (exclude_slave_port_id == INVALID_PORT_ID || + p->getId() != exclude_slave_port_id) { + Tick latency = p->sendAtomicSnoop(pkt); // in contrast to a functional access, we have to keep on // going as all snoopers must be updated even if we get a // response @@ -476,48 +620,51 @@ Bus::recvAtomic(PacketPtr pkt) snoop_response_latency = latency; // restore original packet state for remaining snoopers pkt->cmd = orig_cmd; - pkt->setSrc(src_id); + pkt->setSrc(orig_src_id); pkt->setDest(Packet::Broadcast); } } } - // even if we had a snoop response, we must continue and also - // perform the actual request at the destination - int dest_id = findPort(pkt->getAddr()); - - Tick response_latency = 0; + // the packet is restored as part of the loop and any potential + // snoop response is part of the returned pair + return std::make_pair(snoop_response_cmd, snoop_response_latency); +} - // if this is a snoop from a slave (corresponding to our own - // master), i.e. the memory side of the bus, then do not send it - // back to where it came from - if (dest_id != src_id) { - response_latency = masterPorts[dest_id]->sendAtomic(pkt); +void +Bus::recvFunctional(PacketPtr pkt) +{ + if (!pkt->isPrint()) { + // don't do DPRINTFs on PrintReq as it clutters up the output + DPRINTF(Bus, + "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n", + pkt->getSrc(), pkt->getDest(), pkt->getAddr(), + pkt->cmdString()); } - // if we got a response from a snooper, restore it here - if (snoop_response_cmd != MemCmd::InvalidCmd) { - // no one else should have responded - assert(!pkt->isResponse()); - assert(pkt->cmd == orig_cmd); - pkt->cmd = snoop_response_cmd; - response_latency = snoop_response_latency; - } + // we should always see a request routed based on the address + assert(pkt->getDest() == Packet::Broadcast); + assert(pkt->isRequest()); - // why do we have this packet field and the return value both??? - pkt->finishTime = curTick() + response_latency; - return response_latency; + // forward to all snoopers but the source + forwardFunctional(pkt, pkt->getSrc()); + + // there is no need to continue if the snooping has found what we + // were looking for and the packet is already a response + if (!pkt->isResponse()) { + int dest_id = findPort(pkt->getAddr()); + + masterPorts[dest_id]->sendFunctional(pkt); + } } -/** Function called by the port when the bus is receiving a Functional - * transaction.*/ void -Bus::recvFunctional(PacketPtr pkt) +Bus::recvFunctionalSnoop(PacketPtr pkt) { if (!pkt->isPrint()) { // don't do DPRINTFs on PrintReq as it clutters up the output DPRINTF(Bus, - "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n", + "recvFunctionalSnoop: packet src %d dest %d addr 0x%x cmd %s\n", pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString()); } @@ -526,10 +673,13 @@ Bus::recvFunctional(PacketPtr pkt) assert(pkt->getDest() == Packet::Broadcast); assert(pkt->isRequest()); - // the packet may be changed by another bus on snoops, record the - // source id here - Packet::NodeID src_id = pkt->getSrc(); + // forward to all snoopers + forwardFunctional(pkt, INVALID_PORT_ID); +} +void +Bus::forwardFunctional(PacketPtr pkt, int exclude_slave_port_id) +{ SnoopIter s_end = snoopPorts.end(); for (SnoopIter s_iter = snoopPorts.begin(); s_iter != s_end; s_iter++) { BusSlavePort *p = *s_iter; @@ -537,26 +687,13 @@ Bus::recvFunctional(PacketPtr pkt) // (corresponding to our own slave port that is also in // snoopPorts) and should not send it back to where it came // from - if (p->getId() != src_id) { - p->sendFunctional(pkt); - - // if we get a response we are done - if (pkt->isResponse()) { - break; - } - } - } - - // there is no need to continue if the snooping has found what we - // were looking for and the packet is already a response - if (!pkt->isResponse()) { - int dest_id = findPort(pkt->getAddr()); + if (exclude_slave_port_id == INVALID_PORT_ID || + p->getId() != exclude_slave_port_id) + p->sendFunctionalSnoop(pkt); - // if this is a snoop from a slave (corresponding to our own - // master), i.e. the memory side of the bus, then do not send - // it back to where it came from, - if (dest_id != src_id) { - masterPorts[dest_id]->sendFunctional(pkt); + // if we get a response we are done + if (pkt->isResponse()) { + break; } } } @@ -621,8 +758,7 @@ Bus::recvRangeChange(int id) std::vector<BusSlavePort*>::const_iterator intIter; for (intIter = slavePorts.begin(); intIter != slavePorts.end(); intIter++) - if (*intIter != NULL && (*intIter)->getId() != id) - (*intIter)->sendRangeChange(); + (*intIter)->sendRangeChange(); inRecvRangeChange.erase(id); } |