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/*
* Copyright (c) 2011-2015, 2018-2019 ARM Limited
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* Copyright (c) 2006 The Regents of The University of Michigan
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/**
* @file
* Definition of a non-coherent crossbar object.
*/
#include "mem/noncoherent_xbar.hh"
#include "base/logging.hh"
#include "base/trace.hh"
#include "debug/NoncoherentXBar.hh"
#include "debug/XBar.hh"
namespace gem5
{
NoncoherentXBar::NoncoherentXBar(const NoncoherentXBarParams &p)
: BaseXBar(p)
{
// create the ports based on the size of the memory-side port and
// CPU-side port vector ports, and the presence of the default port,
// the ports are enumerated starting from zero
for (int i = 0; i < p.port_mem_side_ports_connection_count; ++i) {
std::string portName = csprintf("%s.mem_side_port[%d]", name(), i);
RequestPort* bp = new NoncoherentXBarRequestPort(portName, *this, i);
memSidePorts.push_back(bp);
reqLayers.push_back(new ReqLayer(*bp, *this,
csprintf("reqLayer%d", i)));
}
// see if we have a default CPU-side-port device connected and if so add
// our corresponding memory-side port
if (p.port_default_connection_count) {
defaultPortID = memSidePorts.size();
std::string portName = name() + ".default";
RequestPort* bp = new NoncoherentXBarRequestPort(portName, *this,
defaultPortID);
memSidePorts.push_back(bp);
reqLayers.push_back(new ReqLayer(*bp, *this, csprintf("reqLayer%d",
defaultPortID)));
}
// create the CPU-side ports, once again starting at zero
for (int i = 0; i < p.port_cpu_side_ports_connection_count; ++i) {
std::string portName = csprintf("%s.cpu_side_ports[%d]", name(), i);
QueuedResponsePort* bp = new NoncoherentXBarResponsePort(portName,
*this, i);
cpuSidePorts.push_back(bp);
respLayers.push_back(new RespLayer(*bp, *this,
csprintf("respLayer%d", i)));
}
}
NoncoherentXBar::~NoncoherentXBar()
{
for (auto l: reqLayers)
delete l;
for (auto l: respLayers)
delete l;
}
bool
NoncoherentXBar::recvTimingReq(PacketPtr pkt, PortID cpu_side_port_id)
{
// determine the source port based on the id
ResponsePort *src_port = cpuSidePorts[cpu_side_port_id];
// we should never see express snoops on a non-coherent crossbar
assert(!pkt->isExpressSnoop());
// determine the destination based on the address
PortID mem_side_port_id = findPort(pkt->getAddrRange());
// test if the layer should be considered occupied for the current
// port
if (!reqLayers[mem_side_port_id]->tryTiming(src_port)) {
DPRINTF(NoncoherentXBar, "recvTimingReq: src %s %s 0x%x BUSY\n",
src_port->name(), pkt->cmdString(), pkt->getAddr());
return false;
}
DPRINTF(NoncoherentXBar, "recvTimingReq: src %s %s 0x%x\n",
src_port->name(), pkt->cmdString(), pkt->getAddr());
// store size and command as they might be modified when
// forwarding the packet
unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
unsigned int pkt_cmd = pkt->cmdToIndex();
// store the old header delay so we can restore it if needed
Tick old_header_delay = pkt->headerDelay;
// a request sees the frontend and forward latency
Tick xbar_delay = (frontendLatency + forwardLatency) * clockPeriod();
// set the packet header and payload delay
calcPacketTiming(pkt, xbar_delay);
// determine how long to be crossbar layer is busy
Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay;
// before forwarding the packet (and possibly altering it),
// remember if we are expecting a response
const bool expect_response = pkt->needsResponse() &&
!pkt->cacheResponding();
// since it is a normal request, attempt to send the packet
bool success = memSidePorts[mem_side_port_id]->sendTimingReq(pkt);
if (!success) {
DPRINTF(NoncoherentXBar, "recvTimingReq: src %s %s 0x%x RETRY\n",
src_port->name(), pkt->cmdString(), pkt->getAddr());
// restore the header delay as it is additive
pkt->headerDelay = old_header_delay;
// occupy until the header is sent
reqLayers[mem_side_port_id]->failedTiming(src_port,
clockEdge(Cycles(1)));
return false;
}
// remember where to route the response to
if (expect_response) {
assert(routeTo.find(pkt->req) == routeTo.end());
routeTo[pkt->req] = cpu_side_port_id;
}
reqLayers[mem_side_port_id]->succeededTiming(packetFinishTime);
// stats updates
pktCount[cpu_side_port_id][mem_side_port_id]++;
pktSize[cpu_side_port_id][mem_side_port_id] += pkt_size;
transDist[pkt_cmd]++;
return true;
}
bool
NoncoherentXBar::recvTimingResp(PacketPtr pkt, PortID mem_side_port_id)
{
// determine the source port based on the id
RequestPort *src_port = memSidePorts[mem_side_port_id];
// determine the destination
const auto route_lookup = routeTo.find(pkt->req);
assert(route_lookup != routeTo.end());
const PortID cpu_side_port_id = route_lookup->second;
assert(cpu_side_port_id != InvalidPortID);
assert(cpu_side_port_id < respLayers.size());
// test if the layer should be considered occupied for the current
// port
if (!respLayers[cpu_side_port_id]->tryTiming(src_port)) {
DPRINTF(NoncoherentXBar, "recvTimingResp: src %s %s 0x%x BUSY\n",
src_port->name(), pkt->cmdString(), pkt->getAddr());
return false;
}
DPRINTF(NoncoherentXBar, "recvTimingResp: src %s %s 0x%x\n",
src_port->name(), pkt->cmdString(), pkt->getAddr());
// store size and command as they might be modified when
// forwarding the packet
unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
unsigned int pkt_cmd = pkt->cmdToIndex();
// a response sees the response latency
Tick xbar_delay = responseLatency * clockPeriod();
// set the packet header and payload delay
calcPacketTiming(pkt, xbar_delay);
// determine how long to be crossbar layer is busy
Tick packetFinishTime = clockEdge(Cycles(1)) + pkt->payloadDelay;
// send the packet through the destination CPU-side port, and pay for
// any outstanding latency
Tick latency = pkt->headerDelay;
pkt->headerDelay = 0;
cpuSidePorts[cpu_side_port_id]->schedTimingResp(pkt,
curTick() + latency);
// remove the request from the routing table
routeTo.erase(route_lookup);
respLayers[cpu_side_port_id]->succeededTiming(packetFinishTime);
// stats updates
pktCount[cpu_side_port_id][mem_side_port_id]++;
pktSize[cpu_side_port_id][mem_side_port_id] += pkt_size;
transDist[pkt_cmd]++;
return true;
}
void
NoncoherentXBar::recvReqRetry(PortID mem_side_port_id)
{
// responses never block on forwarding them, so the retry will
// always be coming from a port to which we tried to forward a
// request
reqLayers[mem_side_port_id]->recvRetry();
}
Tick
NoncoherentXBar::recvAtomicBackdoor(PacketPtr pkt, PortID cpu_side_port_id,
MemBackdoorPtr *backdoor)
{
DPRINTF(NoncoherentXBar, "recvAtomic: packet src %s addr 0x%x cmd %s\n",
cpuSidePorts[cpu_side_port_id]->name(), pkt->getAddr(),
pkt->cmdString());
unsigned int pkt_size = pkt->hasData() ? pkt->getSize() : 0;
unsigned int pkt_cmd = pkt->cmdToIndex();
// determine the destination port
PortID mem_side_port_id = findPort(pkt->getAddrRange());
// stats updates for the request
pktCount[cpu_side_port_id][mem_side_port_id]++;
pktSize[cpu_side_port_id][mem_side_port_id] += pkt_size;
transDist[pkt_cmd]++;
// forward the request to the appropriate destination
auto mem_side_port = memSidePorts[mem_side_port_id];
Tick response_latency = backdoor ?
mem_side_port->sendAtomicBackdoor(pkt, *backdoor) :
mem_side_port->sendAtomic(pkt);
// add the response data
if (pkt->isResponse()) {
pkt_size = pkt->hasData() ? pkt->getSize() : 0;
pkt_cmd = pkt->cmdToIndex();
// stats updates
pktCount[cpu_side_port_id][mem_side_port_id]++;
pktSize[cpu_side_port_id][mem_side_port_id] += pkt_size;
transDist[pkt_cmd]++;
}
// @todo: Not setting first-word time
pkt->payloadDelay = response_latency;
return response_latency;
}
void
NoncoherentXBar::recvMemBackdoorReq(const MemBackdoorReq &req,
MemBackdoorPtr &backdoor)
{
PortID dest_id = findPort(req.range());
memSidePorts[dest_id]->sendMemBackdoorReq(req, backdoor);
}
void
NoncoherentXBar::recvFunctional(PacketPtr pkt, PortID cpu_side_port_id)
{
if (!pkt->isPrint()) {
// don't do DPRINTFs on PrintReq as it clutters up the output
DPRINTF(NoncoherentXBar,
"recvFunctional: packet src %s addr 0x%x cmd %s\n",
cpuSidePorts[cpu_side_port_id]->name(), pkt->getAddr(),
pkt->cmdString());
}
// since our CPU-side ports are queued ports we need to check them as well
for (const auto& p : cpuSidePorts) {
// if we find a response that has the data, then the
// downstream caches/memories may be out of date, so simply stop
// here
if (p->trySatisfyFunctional(pkt)) {
if (pkt->needsResponse())
pkt->makeResponse();
return;
}
}
// determine the destination port
PortID dest_id = findPort(pkt->getAddrRange());
// forward the request to the appropriate destination
memSidePorts[dest_id]->sendFunctional(pkt);
}
} // namespace gem5