diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/mem/coherent_xbar.cc | 142 | ||||
| -rw-r--r-- | src/mem/coherent_xbar.hh | 9 | ||||
| -rw-r--r-- | src/mem/noncoherent_xbar.cc | 23 | ||||
| -rw-r--r-- | src/mem/xbar.hh | 9 |
4 files changed, 109 insertions, 74 deletions
diff --git a/src/mem/coherent_xbar.cc b/src/mem/coherent_xbar.cc index 6ad7b1785..02580702b 100644 --- a/src/mem/coherent_xbar.cc +++ b/src/mem/coherent_xbar.cc @@ -142,6 +142,10 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id) // remember if the packet is an express snoop bool is_express_snoop = pkt->isExpressSnoop(); + bool is_inhibited = pkt->memInhibitAsserted(); + // for normal requests, going downstream, the express snoop flag + // and the inhibited flag should always be the same + assert(is_express_snoop == is_inhibited); // determine the destination based on the address PortID master_port_id = findPort(pkt->getAddr()); @@ -163,9 +167,6 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id) unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; unsigned int pkt_cmd = pkt->cmdToIndex(); - // set the source port for routing of the response - pkt->setSrc(slave_port_id); - calcPacketTiming(pkt); Tick packetFinishTime = pkt->lastWordDelay + curTick(); @@ -187,21 +188,10 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_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 = !is_express_snoop && 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); - } + // remember if the packet will generate a snoop response + const bool expect_snoop_resp = !is_inhibited && pkt->memInhibitAsserted(); + const bool expect_response = pkt->needsResponse() && + !pkt->memInhibitAsserted(); // Note: Cannot create a copy of the full packet, here. MemCmd orig_cmd(pkt->cmd); @@ -224,41 +214,58 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id) pkt->cmd = tmp_cmd; } - // if this is an express snoop, we are done at this point - if (is_express_snoop) { - assert(success); - snoops++; - } else { - // for normal requests, check if successful - if (!success) { - // inhibited packets should never be forced to retry - assert(!pkt->memInhibitAsserted()); + // check if we were successful in sending the packet onwards + if (!success) { + // express snoops and inhibited packets should never be forced + // to retry + assert(!is_express_snoop); + assert(!pkt->memInhibitAsserted()); - // if it was added as outstanding and the send failed, then - // erase it again - if (add_outstanding) - outstandingReq.erase(pkt->req); + // undo the calculation so we can check for 0 again + pkt->firstWordDelay = pkt->lastWordDelay = 0; - // undo the calculation so we can check for 0 again - pkt->firstWordDelay = pkt->lastWordDelay = 0; + DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x RETRY\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); - DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x RETRY\n", - src_port->name(), pkt->cmdString(), pkt->getAddr()); + // update the layer state and schedule an idle event + reqLayers[master_port_id]->failedTiming(src_port, + clockEdge(headerCycles)); + } else { + // express snoops currently bypass the crossbar state entirely + if (!is_express_snoop) { + // if this particular request will generate a snoop + // response + if (expect_snoop_resp) { + // we should never have an exsiting request outstanding + assert(outstandingSnoop.find(pkt->req) == + outstandingSnoop.end()); + outstandingSnoop.insert(pkt->req); + + // basic sanity check on the outstanding snoops + panic_if(outstandingSnoop.size() > 512, + "Outstanding snoop requests exceeded 512\n"); + } + + // remember where to route the normal response to + if (expect_response || expect_snoop_resp) { + assert(routeTo.find(pkt->req) == routeTo.end()); + routeTo[pkt->req] = slave_port_id; + + panic_if(routeTo.size() > 512, + "Routing table exceeds 512 packets\n"); + } - // update the layer state and schedule an idle event - reqLayers[master_port_id]->failedTiming(src_port, - clockEdge(headerCycles)); - } else { // update the layer state and schedule an idle event reqLayers[master_port_id]->succeededTiming(packetFinishTime); } - } - // stats updates only consider packets that were successfully sent - if (success) { + // stats updates only consider packets that were successfully sent pktCount[slave_port_id][master_port_id]++; pktSize[slave_port_id][master_port_id] += pkt_size; transDist[pkt_cmd]++; + + if (is_express_snoop) + snoops++; } return success; @@ -270,8 +277,10 @@ CoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) // determine the source port based on the id MasterPort *src_port = masterPorts[master_port_id]; - // determine the destination based on what is stored in the packet - PortID slave_port_id = pkt->getDest(); + // determine the destination + const auto route_lookup = routeTo.find(pkt->req); + assert(route_lookup != routeTo.end()); + const PortID slave_port_id = route_lookup->second; assert(slave_port_id != InvalidPortID); assert(slave_port_id < respLayers.size()); @@ -294,18 +303,11 @@ CoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) calcPacketTiming(pkt); Tick packetFinishTime = pkt->lastWordDelay + curTick(); - // the packet is a normal response to a request that we should - // have seen passing through the crossbar - assert(outstandingReq.find(pkt->req) != outstandingReq.end()); - if (snoopFilter && !pkt->req->isUncacheable() && !system->bypassCaches()) { // let the snoop filter inspect the response and update its state snoopFilter->updateResponse(pkt, *slavePorts[slave_port_id]); } - // remove it as outstanding - outstandingReq.erase(pkt->req); - // send the packet through the destination slave port bool success M5_VAR_USED = slavePorts[slave_port_id]->sendTimingResp(pkt); @@ -313,6 +315,9 @@ CoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) // deadlock assert(success); + // remove the request from the routing table + routeTo.erase(route_lookup); + respLayers[slave_port_id]->succeededTiming(packetFinishTime); // stats updates @@ -337,8 +342,8 @@ CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id) // we should only see express snoops from caches assert(pkt->isExpressSnoop()); - // set the source port for routing of the response - pkt->setSrc(master_port_id); + // remeber if the packet is inhibited so we can see if it changes + const bool is_inhibited = pkt->memInhibitAsserted(); if (snoopFilter) { // let the Snoop Filter work its magic and guide probing @@ -355,6 +360,12 @@ CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id) forwardTiming(pkt, InvalidPortID); } + // if we can expect a response, remember how to route it + if (!is_inhibited && pkt->memInhibitAsserted()) { + assert(routeTo.find(pkt->req) == routeTo.end()); + routeTo[pkt->req] = master_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 @@ -369,16 +380,18 @@ CoherentXBar::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) // determine the source port based on the id SlavePort* src_port = slavePorts[slave_port_id]; - // get the destination from the packet - PortID dest_port_id = pkt->getDest(); + // get the destination + const auto route_lookup = routeTo.find(pkt->req); + assert(route_lookup != routeTo.end()); + const PortID dest_port_id = route_lookup->second; assert(dest_port_id != InvalidPortID); // 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 + // should be in the outstandingSnoop), or if we merely forwarded // someone else's snoop request - bool forwardAsSnoop = outstandingReq.find(pkt->req) == - outstandingReq.end(); + const bool forwardAsSnoop = outstandingSnoop.find(pkt->req) == + outstandingSnoop.end(); // test if the crossbar should be considered occupied for the // current port, note that the check is bypassed if the response @@ -440,13 +453,11 @@ CoherentXBar::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) // i.e. from a coherent master connected to the crossbar, and // since we created the snoop request as part of recvTiming, // this should now be a normal response again - outstandingReq.erase(pkt->req); + outstandingSnoop.erase(pkt->req); - // this is a snoop response from a coherent master, with a - // destination field set on its way through the crossbar as - // request, hence it should never go back to where the snoop - // response came from, but instead to where the original - // request came from + // this is a snoop response from a coherent master, hence it + // should never go back to where the snoop response came from, + // but instead to where the original request came from assert(slave_port_id != dest_port_id); if (snoopFilter) { @@ -476,6 +487,9 @@ CoherentXBar::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) respLayers[dest_port_id]->succeededTiming(packetFinishTime); } + // remove the request from the routing table + routeTo.erase(route_lookup); + // stats updates transDist[pkt_cmd]++; snoops++; diff --git a/src/mem/coherent_xbar.hh b/src/mem/coherent_xbar.hh index fd4dd1cca..446c0b577 100644 --- a/src/mem/coherent_xbar.hh +++ b/src/mem/coherent_xbar.hh @@ -51,7 +51,6 @@ #ifndef __MEM_COHERENT_XBAR_HH__ #define __MEM_COHERENT_XBAR_HH__ -#include "base/hashmap.hh" #include "mem/snoop_filter.hh" #include "mem/xbar.hh" #include "params/CoherentXBar.hh" @@ -259,11 +258,11 @@ class CoherentXBar : public BaseXBar std::vector<SlavePort*> snoopPorts; /** - * Store the outstanding requests so we can determine which ones - * we generated and which ones were merely forwarded. This is used - * in the coherent crossbar when coherency responses come back. + * Store the outstanding requests that we are expecting snoop + * responses from so we can determine which snoop responses we + * generated and which ones were merely forwarded. */ - m5::hash_set<RequestPtr> outstandingReq; + m5::hash_set<RequestPtr> outstandingSnoop; /** * Keep a pointer to the system to be allow to querying memory system diff --git a/src/mem/noncoherent_xbar.cc b/src/mem/noncoherent_xbar.cc index 476b8314f..e93446b47 100644 --- a/src/mem/noncoherent_xbar.cc +++ b/src/mem/noncoherent_xbar.cc @@ -127,12 +127,14 @@ NoncoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id) unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0; unsigned int pkt_cmd = pkt->cmdToIndex(); - // set the source port for routing of the response - pkt->setSrc(slave_port_id); - calcPacketTiming(pkt); Tick packetFinishTime = pkt->lastWordDelay + curTick(); + // before forwarding the packet (and possibly altering it), + // remember if we are expecting a response + const bool expect_response = pkt->needsResponse() && + !pkt->memInhibitAsserted(); + // since it is a normal request, attempt to send the packet bool success = masterPorts[master_port_id]->sendTimingReq(pkt); @@ -153,6 +155,12 @@ NoncoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id) return false; } + // remember where to route the response to + if (expect_response) { + assert(routeTo.find(pkt->req) == routeTo.end()); + routeTo[pkt->req] = slave_port_id; + } + reqLayers[master_port_id]->succeededTiming(packetFinishTime); // stats updates @@ -169,8 +177,10 @@ NoncoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) // determine the source port based on the id MasterPort *src_port = masterPorts[master_port_id]; - // determine the destination based on what is stored in the packet - PortID slave_port_id = pkt->getDest(); + // determine the destination + const auto route_lookup = routeTo.find(pkt->req); + assert(route_lookup != routeTo.end()); + const PortID slave_port_id = route_lookup->second; assert(slave_port_id != InvalidPortID); assert(slave_port_id < respLayers.size()); @@ -200,6 +210,9 @@ NoncoherentXBar::recvTimingResp(PacketPtr pkt, PortID master_port_id) // deadlock assert(success); + // remove the request from the routing table + routeTo.erase(route_lookup); + respLayers[slave_port_id]->succeededTiming(packetFinishTime); // stats updates diff --git a/src/mem/xbar.hh b/src/mem/xbar.hh index 7f3c17677..6e7d7afce 100644 --- a/src/mem/xbar.hh +++ b/src/mem/xbar.hh @@ -54,6 +54,7 @@ #include <deque> #include "base/addr_range_map.hh" +#include "base/hashmap.hh" #include "base/types.hh" #include "mem/mem_object.hh" #include "params/BaseXBar.hh" @@ -247,6 +248,14 @@ class BaseXBar : public MemObject AddrRangeMap<PortID> portMap; + /** + * Remember where request packets came from so that we can route + * responses to the appropriate port. This relies on the fact that + * the underlying Request pointer inside the Packet stays + * constant. + */ + m5::unordered_map<RequestPtr, PortID> routeTo; + /** all contigous ranges seen by this crossbar */ AddrRangeList xbarRanges; |