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/*
* Copyright (c) 2013 - 2016 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met: redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer;
* redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution;
* neither the name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "cpu/trace/trace_cpu.hh"
#include "sim/sim_exit.hh"
// Declare and initialize the static counter for number of trace CPUs.
int TraceCPU::numTraceCPUs = 0;
TraceCPU::TraceCPU(TraceCPUParams *params)
: BaseCPU(params),
icachePort(this),
dcachePort(this),
instMasterID(params->system->getMasterId(this, "inst")),
dataMasterID(params->system->getMasterId(this, "data")),
instTraceFile(params->instTraceFile),
dataTraceFile(params->dataTraceFile),
icacheGen(*this, ".iside", icachePort, instMasterID, instTraceFile),
dcacheGen(*this, ".dside", dcachePort, dataMasterID, dataTraceFile,
params),
icacheNextEvent([this]{ schedIcacheNext(); }, name()),
dcacheNextEvent([this]{ schedDcacheNext(); }, name()),
oneTraceComplete(false),
traceOffset(0),
execCompleteEvent(nullptr),
enableEarlyExit(params->enableEarlyExit),
progressMsgInterval(params->progressMsgInterval),
progressMsgThreshold(params->progressMsgInterval)
{
// Increment static counter for number of Trace CPUs.
++TraceCPU::numTraceCPUs;
// Check that the python parameters for sizes of ROB, store buffer and
// load buffer do not overflow the corresponding C++ variables.
fatal_if(params->sizeROB > UINT16_MAX, "ROB size set to %d exceeds the "
"max. value of %d.\n", params->sizeROB, UINT16_MAX);
fatal_if(params->sizeStoreBuffer > UINT16_MAX, "ROB size set to %d "
"exceeds the max. value of %d.\n", params->sizeROB,
UINT16_MAX);
fatal_if(params->sizeLoadBuffer > UINT16_MAX, "Load buffer size set to"
" %d exceeds the max. value of %d.\n",
params->sizeLoadBuffer, UINT16_MAX);
}
TraceCPU::~TraceCPU()
{
}
TraceCPU*
TraceCPUParams::create()
{
return new TraceCPU(this);
}
void
TraceCPU::updateNumOps(uint64_t rob_num)
{
numOps = rob_num;
if (progressMsgInterval != 0 && numOps.value() >= progressMsgThreshold) {
inform("%s: %i insts committed\n", name(), progressMsgThreshold);
progressMsgThreshold += progressMsgInterval;
}
}
void
TraceCPU::takeOverFrom(BaseCPU *oldCPU)
{
// Unbind the ports of the old CPU and bind the ports of the TraceCPU.
getInstPort().takeOverFrom(&oldCPU->getInstPort());
getDataPort().takeOverFrom(&oldCPU->getDataPort());
}
void
TraceCPU::init()
{
DPRINTF(TraceCPUInst, "Instruction fetch request trace file is \"%s\"."
"\n", instTraceFile);
DPRINTF(TraceCPUData, "Data memory request trace file is \"%s\".\n",
dataTraceFile);
BaseCPU::init();
// Get the send tick of the first instruction read request
Tick first_icache_tick = icacheGen.init();
// Get the send tick of the first data read/write request
Tick first_dcache_tick = dcacheGen.init();
// Set the trace offset as the minimum of that in both traces
traceOffset = std::min(first_icache_tick, first_dcache_tick);
inform("%s: Time offset (tick) found as min of both traces is %lli.\n",
name(), traceOffset);
// Schedule next icache and dcache event by subtracting the offset
schedule(icacheNextEvent, first_icache_tick - traceOffset);
schedule(dcacheNextEvent, first_dcache_tick - traceOffset);
// Adjust the trace offset for the dcache generator's ready nodes
// We don't need to do this for the icache generator as it will
// send its first request at the first event and schedule subsequent
// events using a relative tick delta
dcacheGen.adjustInitTraceOffset(traceOffset);
// If the Trace CPU simulation is configured to exit on any one trace
// completion then we don't need a counted event to count down all Trace
// CPUs in the system. If not then instantiate a counted event.
if (!enableEarlyExit) {
// The static counter for number of Trace CPUs is correctly set at
// this point so create an event and pass it.
execCompleteEvent = new CountedExitEvent("end of all traces reached.",
numTraceCPUs);
}
}
void
TraceCPU::schedIcacheNext()
{
DPRINTF(TraceCPUInst, "IcacheGen event.\n");
// Try to send the current packet or a retry packet if there is one
bool sched_next = icacheGen.tryNext();
// If packet sent successfully, schedule next event
if (sched_next) {
DPRINTF(TraceCPUInst, "Scheduling next icacheGen event "
"at %d.\n", curTick() + icacheGen.tickDelta());
schedule(icacheNextEvent, curTick() + icacheGen.tickDelta());
++numSchedIcacheEvent;
} else {
// check if traceComplete. If not, do nothing because sending failed
// and next event will be scheduled via RecvRetry()
if (icacheGen.isTraceComplete()) {
// If this is the first trace to complete, set the variable. If it
// is already set then both traces are complete to exit sim.
checkAndSchedExitEvent();
}
}
return;
}
void
TraceCPU::schedDcacheNext()
{
DPRINTF(TraceCPUData, "DcacheGen event.\n");
// Update stat for numCycles
numCycles = clockEdge() / clockPeriod();
dcacheGen.execute();
if (dcacheGen.isExecComplete()) {
checkAndSchedExitEvent();
}
}
void
TraceCPU::checkAndSchedExitEvent()
{
if (!oneTraceComplete) {
oneTraceComplete = true;
} else {
// Schedule event to indicate execution is complete as both
// instruction and data access traces have been played back.
inform("%s: Execution complete.\n", name());
// If the replay is configured to exit early, that is when any one
// execution is complete then exit immediately and return. Otherwise,
// schedule the counted exit that counts down completion of each Trace
// CPU.
if (enableEarlyExit) {
exitSimLoop("End of trace reached");
} else {
schedule(*execCompleteEvent, curTick());
}
}
}
void
TraceCPU::regStats()
{
BaseCPU::regStats();
numSchedDcacheEvent
.name(name() + ".numSchedDcacheEvent")
.desc("Number of events scheduled to trigger data request generator")
;
numSchedIcacheEvent
.name(name() + ".numSchedIcacheEvent")
.desc("Number of events scheduled to trigger instruction request generator")
;
numOps
.name(name() + ".numOps")
.desc("Number of micro-ops simulated by the Trace CPU")
;
cpi
.name(name() + ".cpi")
.desc("Cycles per micro-op used as a proxy for CPI")
.precision(6)
;
cpi = numCycles/numOps;
icacheGen.regStats();
dcacheGen.regStats();
}
void
TraceCPU::ElasticDataGen::regStats()
{
using namespace Stats;
maxDependents
.name(name() + ".maxDependents")
.desc("Max number of dependents observed on a node")
;
maxReadyListSize
.name(name() + ".maxReadyListSize")
.desc("Max size of the ready list observed")
;
numSendAttempted
.name(name() + ".numSendAttempted")
.desc("Number of first attempts to send a request")
;
numSendSucceeded
.name(name() + ".numSendSucceeded")
.desc("Number of successful first attempts")
;
numSendFailed
.name(name() + ".numSendFailed")
.desc("Number of failed first attempts")
;
numRetrySucceeded
.name(name() + ".numRetrySucceeded")
.desc("Number of successful retries")
;
numSplitReqs
.name(name() + ".numSplitReqs")
.desc("Number of split requests")
;
numSOLoads
.name(name() + ".numSOLoads")
.desc("Number of strictly ordered loads")
;
numSOStores
.name(name() + ".numSOStores")
.desc("Number of strictly ordered stores")
;
dataLastTick
.name(name() + ".dataLastTick")
.desc("Last tick simulated from the elastic data trace")
;
}
Tick
TraceCPU::ElasticDataGen::init()
{
DPRINTF(TraceCPUData, "Initializing data memory request generator "
"DcacheGen: elastic issue with retry.\n");
if (!readNextWindow())
panic("Trace has %d elements. It must have at least %d elements.\n",
depGraph.size(), 2 * windowSize);
DPRINTF(TraceCPUData, "After 1st read, depGraph size:%d.\n",
depGraph.size());
if (!readNextWindow())
panic("Trace has %d elements. It must have at least %d elements.\n",
depGraph.size(), 2 * windowSize);
DPRINTF(TraceCPUData, "After 2st read, depGraph size:%d.\n",
depGraph.size());
// Print readyList
if (DTRACE(TraceCPUData)) {
printReadyList();
}
auto free_itr = readyList.begin();
DPRINTF(TraceCPUData, "Execute tick of the first dependency free node %lli"
" is %d.\n", free_itr->seqNum, free_itr->execTick);
// Return the execute tick of the earliest ready node so that an event
// can be scheduled to call execute()
return (free_itr->execTick);
}
void
TraceCPU::ElasticDataGen::adjustInitTraceOffset(Tick& offset) {
for (auto& free_node : readyList) {
free_node.execTick -= offset;
}
}
void
TraceCPU::ElasticDataGen::exit()
{
trace.reset();
}
bool
TraceCPU::ElasticDataGen::readNextWindow()
{
// Read and add next window
DPRINTF(TraceCPUData, "Reading next window from file.\n");
if (traceComplete) {
// We are at the end of the file, thus we have no more records.
// Return false.
return false;
}
DPRINTF(TraceCPUData, "Start read: Size of depGraph is %d.\n",
depGraph.size());
uint32_t num_read = 0;
while (num_read != windowSize) {
// Create a new graph node
GraphNode* new_node = new GraphNode;
// Read the next line to get the next record. If that fails then end of
// trace has been reached and traceComplete needs to be set in addition
// to returning false.
if (!trace.read(new_node)) {
DPRINTF(TraceCPUData, "\tTrace complete!\n");
traceComplete = true;
return false;
}
// Annotate the ROB dependencies of the new node onto the parent nodes.
addDepsOnParent(new_node, new_node->robDep, new_node->numRobDep);
// Annotate the register dependencies of the new node onto the parent
// nodes.
addDepsOnParent(new_node, new_node->regDep, new_node->numRegDep);
num_read++;
// Add to map
depGraph[new_node->seqNum] = new_node;
if (new_node->numRobDep == 0 && new_node->numRegDep == 0) {
// Source dependencies are already complete, check if resources
// are available and issue. The execution time is approximated
// to current time plus the computational delay.
checkAndIssue(new_node);
}
}
DPRINTF(TraceCPUData, "End read: Size of depGraph is %d.\n",
depGraph.size());
return true;
}
template<typename T> void
TraceCPU::ElasticDataGen::addDepsOnParent(GraphNode *new_node,
T& dep_array, uint8_t& num_dep)
{
for (auto& a_dep : dep_array) {
// The convention is to set the dependencies starting with the first
// index in the ROB and register dependency arrays. Thus, when we reach
// a dependency equal to the initialisation value of zero, we know have
// iterated over all dependencies and can break.
if (a_dep == 0)
break;
// We look up the valid dependency, i.e. the parent of this node
auto parent_itr = depGraph.find(a_dep);
if (parent_itr != depGraph.end()) {
// If the parent is found, it is yet to be executed. Append a
// pointer to the new node to the dependents list of the parent
// node.
parent_itr->second->dependents.push_back(new_node);
auto num_depts = parent_itr->second->dependents.size();
maxDependents = std::max<double>(num_depts, maxDependents.value());
} else {
// The dependency is not found in the graph. So consider
// the execution of the parent is complete, i.e. remove this
// dependency.
a_dep = 0;
num_dep--;
}
}
}
void
TraceCPU::ElasticDataGen::execute()
{
DPRINTF(TraceCPUData, "Execute start occupancy:\n");
DPRINTFR(TraceCPUData, "\tdepGraph = %d, readyList = %d, "
"depFreeQueue = %d ,", depGraph.size(), readyList.size(),
depFreeQueue.size());
hwResource.printOccupancy();
// Read next window to make sure that dependents of all dep-free nodes
// are in the depGraph
if (nextRead) {
readNextWindow();
nextRead = false;
}
// First attempt to issue the pending dependency-free nodes held
// in depFreeQueue. If resources have become available for a node,
// then issue it, i.e. add the node to readyList.
while (!depFreeQueue.empty()) {
if (checkAndIssue(depFreeQueue.front(), false)) {
DPRINTF(TraceCPUData, "Removing from depFreeQueue: seq. num "
"%lli.\n", (depFreeQueue.front())->seqNum);
depFreeQueue.pop();
} else {
break;
}
}
// Proceed to execute from readyList
auto graph_itr = depGraph.begin();
auto free_itr = readyList.begin();
// Iterate through readyList until the next free node has its execute
// tick later than curTick or the end of readyList is reached
while (free_itr->execTick <= curTick() && free_itr != readyList.end()) {
// Get pointer to the node to be executed
graph_itr = depGraph.find(free_itr->seqNum);
assert(graph_itr != depGraph.end());
GraphNode* node_ptr = graph_itr->second;
// If there is a retryPkt send that else execute the load
if (retryPkt) {
// The retryPkt must be the request that was created by the
// first node in the readyList.
if (retryPkt->req->getReqInstSeqNum() != node_ptr->seqNum) {
panic("Retry packet's seqence number does not match "
"the first node in the readyList.\n");
}
if (port.sendTimingReq(retryPkt)) {
++numRetrySucceeded;
retryPkt = nullptr;
}
} else if (node_ptr->isLoad() || node_ptr->isStore()) {
// If there is no retryPkt, attempt to send a memory request in
// case of a load or store node. If the send fails, executeMemReq()
// returns a packet pointer, which we save in retryPkt. In case of
// a comp node we don't do anything and simply continue as if the
// execution of the comp node succedded.
retryPkt = executeMemReq(node_ptr);
}
// If the retryPkt or a new load/store node failed, we exit from here
// as a retry from cache will bring the control to execute(). The
// first node in readyList then, will be the failed node.
if (retryPkt) {
break;
}
// Proceed to remove dependencies for the successfully executed node.
// If it is a load which is not strictly ordered and we sent a
// request for it successfully, we do not yet mark any register
// dependencies complete. But as per dependency modelling we need
// to mark ROB dependencies of load and non load/store nodes which
// are based on successful sending of the load as complete.
if (node_ptr->isLoad() && !node_ptr->isStrictlyOrdered()) {
// If execute succeeded mark its dependents as complete
DPRINTF(TraceCPUData, "Node seq. num %lli sent. Waking up "
"dependents..\n", node_ptr->seqNum);
auto child_itr = (node_ptr->dependents).begin();
while (child_itr != (node_ptr->dependents).end()) {
// ROB dependency of a store on a load must not be removed
// after load is sent but after response is received
if (!(*child_itr)->isStore() &&
(*child_itr)->removeRobDep(node_ptr->seqNum)) {
// Check if the child node has become dependency free
if ((*child_itr)->numRobDep == 0 &&
(*child_itr)->numRegDep == 0) {
// Source dependencies are complete, check if
// resources are available and issue
checkAndIssue(*child_itr);
}
// Remove this child for the sent load and point to new
// location of the element following the erased element
child_itr = node_ptr->dependents.erase(child_itr);
} else {
// This child is not dependency-free, point to the next
// child
child_itr++;
}
}
} else {
// If it is a strictly ordered load mark its dependents as complete
// as we do not send a request for this case. If it is a store or a
// comp node we also mark all its dependents complete.
DPRINTF(TraceCPUData, "Node seq. num %lli done. Waking"
" up dependents..\n", node_ptr->seqNum);
for (auto child : node_ptr->dependents) {
// If the child node is dependency free removeDepOnInst()
// returns true.
if (child->removeDepOnInst(node_ptr->seqNum)) {
// Source dependencies are complete, check if resources
// are available and issue
checkAndIssue(child);
}
}
}
// After executing the node, remove from readyList and delete node.
readyList.erase(free_itr);
// If it is a cacheable load which was sent, don't delete
// just yet. Delete it in completeMemAccess() after the
// response is received. If it is an strictly ordered
// load, it was not sent and all dependencies were simply
// marked complete. Thus it is safe to delete it. For
// stores and non load/store nodes all dependencies were
// marked complete so it is safe to delete it.
if (!node_ptr->isLoad() || node_ptr->isStrictlyOrdered()) {
// Release all resources occupied by the completed node
hwResource.release(node_ptr);
// clear the dynamically allocated set of dependents
(node_ptr->dependents).clear();
// Update the stat for numOps simulated
owner.updateNumOps(node_ptr->robNum);
// delete node
delete node_ptr;
// remove from graph
depGraph.erase(graph_itr);
}
// Point to first node to continue to next iteration of while loop
free_itr = readyList.begin();
} // end of while loop
// Print readyList, sizes of queues and resource status after updating
if (DTRACE(TraceCPUData)) {
printReadyList();
DPRINTF(TraceCPUData, "Execute end occupancy:\n");
DPRINTFR(TraceCPUData, "\tdepGraph = %d, readyList = %d, "
"depFreeQueue = %d ,", depGraph.size(), readyList.size(),
depFreeQueue.size());
hwResource.printOccupancy();
}
if (retryPkt) {
DPRINTF(TraceCPUData, "Not scheduling an event as expecting a retry"
"event from the cache for seq. num %lli.\n",
retryPkt->req->getReqInstSeqNum());
return;
}
// If the size of the dependency graph is less than the dependency window
// then read from the trace file to populate the graph next time we are in
// execute.
if (depGraph.size() < windowSize && !traceComplete)
nextRead = true;
// If cache is not blocked, schedule an event for the first execTick in
// readyList else retry from cache will schedule the event. If the ready
// list is empty then check if the next pending node has resources
// available to issue. If yes, then schedule an event for the next cycle.
if (!readyList.empty()) {
Tick next_event_tick = std::max(readyList.begin()->execTick,
curTick());
DPRINTF(TraceCPUData, "Attempting to schedule @%lli.\n",
next_event_tick);
owner.schedDcacheNextEvent(next_event_tick);
} else if (readyList.empty() && !depFreeQueue.empty() &&
hwResource.isAvailable(depFreeQueue.front())) {
DPRINTF(TraceCPUData, "Attempting to schedule @%lli.\n",
owner.clockEdge(Cycles(1)));
owner.schedDcacheNextEvent(owner.clockEdge(Cycles(1)));
}
// If trace is completely read, readyList is empty and depGraph is empty,
// set execComplete to true
if (depGraph.empty() && readyList.empty() && traceComplete &&
!hwResource.awaitingResponse()) {
DPRINTF(TraceCPUData, "\tExecution Complete!\n");
execComplete = true;
dataLastTick = curTick();
}
}
PacketPtr
TraceCPU::ElasticDataGen::executeMemReq(GraphNode* node_ptr)
{
DPRINTF(TraceCPUData, "Executing memory request %lli (phys addr %d, "
"virt addr %d, pc %#x, size %d, flags %d).\n",
node_ptr->seqNum, node_ptr->physAddr, node_ptr->virtAddr,
node_ptr->pc, node_ptr->size, node_ptr->flags);
// If the request is strictly ordered, do not send it. Just return nullptr
// as if it was succesfully sent.
if (node_ptr->isStrictlyOrdered()) {
node_ptr->isLoad() ? ++numSOLoads : ++numSOStores;
DPRINTF(TraceCPUData, "Skipping strictly ordered request %lli.\n",
node_ptr->seqNum);
return nullptr;
}
// Check if the request spans two cache lines as this condition triggers
// an assert fail in the L1 cache. If it does then truncate the size to
// access only until the end of that line and ignore the remainder. The
// stat counting this is useful to keep a check on how frequently this
// happens. If required the code could be revised to mimick splitting such
// a request into two.
unsigned blk_size = owner.cacheLineSize();
Addr blk_offset = (node_ptr->physAddr & (Addr)(blk_size - 1));
if (!(blk_offset + node_ptr->size <= blk_size)) {
node_ptr->size = blk_size - blk_offset;
++numSplitReqs;
}
// Create a request and the packet containing request
auto req = std::make_shared<Request>(
node_ptr->physAddr, node_ptr->size, node_ptr->flags, masterID);
req->setReqInstSeqNum(node_ptr->seqNum);
req->setPC(node_ptr->pc);
// If virtual address is valid, set the virtual address field
// of the request.
if (node_ptr->virtAddr != 0) {
req->setVirt(node_ptr->virtAddr, node_ptr->size,
node_ptr->flags, masterID, node_ptr->pc);
req->setPaddr(node_ptr->physAddr);
req->setReqInstSeqNum(node_ptr->seqNum);
}
PacketPtr pkt;
uint8_t* pkt_data = new uint8_t[req->getSize()];
if (node_ptr->isLoad()) {
pkt = Packet::createRead(req);
} else {
pkt = Packet::createWrite(req);
memset(pkt_data, 0xA, req->getSize());
}
pkt->dataDynamic(pkt_data);
// Call MasterPort method to send a timing request for this packet
bool success = port.sendTimingReq(pkt);
++numSendAttempted;
if (!success) {
// If it fails, return the packet to retry when a retry is signalled by
// the cache
++numSendFailed;
DPRINTF(TraceCPUData, "Send failed. Saving packet for retry.\n");
return pkt;
} else {
// It is succeeds, return nullptr
++numSendSucceeded;
return nullptr;
}
}
bool
TraceCPU::ElasticDataGen::checkAndIssue(const GraphNode* node_ptr, bool first)
{
// Assert the node is dependency-free
assert(node_ptr->numRobDep == 0 && node_ptr->numRegDep == 0);
// If this is the first attempt, print a debug message to indicate this.
if (first) {
DPRINTFR(TraceCPUData, "\t\tseq. num %lli(%s) with rob num %lli is now"
" dependency free.\n", node_ptr->seqNum, node_ptr->typeToStr(),
node_ptr->robNum);
}
// Check if resources are available to issue the specific node
if (hwResource.isAvailable(node_ptr)) {
// If resources are free only then add to readyList
DPRINTFR(TraceCPUData, "\t\tResources available for seq. num %lli. Adding"
" to readyList, occupying resources.\n", node_ptr->seqNum);
// Compute the execute tick by adding the compute delay for the node
// and add the ready node to the ready list
addToSortedReadyList(node_ptr->seqNum,
owner.clockEdge() + node_ptr->compDelay);
// Account for the resources taken up by this issued node.
hwResource.occupy(node_ptr);
return true;
} else {
if (first) {
// Although dependencies are complete, resources are not available.
DPRINTFR(TraceCPUData, "\t\tResources unavailable for seq. num %lli."
" Adding to depFreeQueue.\n", node_ptr->seqNum);
depFreeQueue.push(node_ptr);
} else {
DPRINTFR(TraceCPUData, "\t\tResources unavailable for seq. num %lli. "
"Still pending issue.\n", node_ptr->seqNum);
}
return false;
}
}
void
TraceCPU::ElasticDataGen::completeMemAccess(PacketPtr pkt)
{
// Release the resources for this completed node.
if (pkt->isWrite()) {
// Consider store complete.
hwResource.releaseStoreBuffer();
// If it is a store response then do nothing since we do not model
// dependencies on store completion in the trace. But if we were
// blocking execution due to store buffer fullness, we need to schedule
// an event and attempt to progress.
} else {
// If it is a load response then release the dependents waiting on it.
// Get pointer to the completed load
auto graph_itr = depGraph.find(pkt->req->getReqInstSeqNum());
assert(graph_itr != depGraph.end());
GraphNode* node_ptr = graph_itr->second;
// Release resources occupied by the load
hwResource.release(node_ptr);
DPRINTF(TraceCPUData, "Load seq. num %lli response received. Waking up"
" dependents..\n", node_ptr->seqNum);
for (auto child : node_ptr->dependents) {
if (child->removeDepOnInst(node_ptr->seqNum)) {
checkAndIssue(child);
}
}
// clear the dynamically allocated set of dependents
(node_ptr->dependents).clear();
// Update the stat for numOps completed
owner.updateNumOps(node_ptr->robNum);
// delete node
delete node_ptr;
// remove from graph
depGraph.erase(graph_itr);
}
if (DTRACE(TraceCPUData)) {
printReadyList();
}
// If the size of the dependency graph is less than the dependency window
// then read from the trace file to populate the graph next time we are in
// execute.
if (depGraph.size() < windowSize && !traceComplete)
nextRead = true;
// If not waiting for retry, attempt to schedule next event
if (!retryPkt) {
// We might have new dep-free nodes in the list which will have execute
// tick greater than or equal to curTick. But a new dep-free node might
// have its execute tick earlier. Therefore, attempt to reschedule. It
// could happen that the readyList is empty and we got here via a
// last remaining response. So, either the trace is complete or there
// are pending nodes in the depFreeQueue. The checking is done in the
// execute() control flow, so schedule an event to go via that flow.
Tick next_event_tick = readyList.empty() ? owner.clockEdge(Cycles(1)) :
std::max(readyList.begin()->execTick, owner.clockEdge(Cycles(1)));
DPRINTF(TraceCPUData, "Attempting to schedule @%lli.\n",
next_event_tick);
owner.schedDcacheNextEvent(next_event_tick);
}
}
void
TraceCPU::ElasticDataGen::addToSortedReadyList(NodeSeqNum seq_num,
Tick exec_tick)
{
ReadyNode ready_node;
ready_node.seqNum = seq_num;
ready_node.execTick = exec_tick;
// Iterator to readyList
auto itr = readyList.begin();
// If the readyList is empty, simply insert the new node at the beginning
// and return
if (itr == readyList.end()) {
readyList.insert(itr, ready_node);
maxReadyListSize = std::max<double>(readyList.size(),
maxReadyListSize.value());
return;
}
// If the new node has its execution tick equal to the first node in the
// list then go to the next node. If the first node in the list failed
// to execute, its position as the first is thus maintained.
if (retryPkt)
if (retryPkt->req->getReqInstSeqNum() == itr->seqNum)
itr++;
// Increment the iterator and compare the node pointed to by it to the new
// node till the position to insert the new node is found.
bool found = false;
while (!found && itr != readyList.end()) {
// If the execution tick of the new node is less than the node then
// this is the position to insert
if (exec_tick < itr->execTick)
found = true;
// If the execution tick of the new node is equal to the node then
// sort in ascending order of sequence numbers
else if (exec_tick == itr->execTick) {
// If the sequence number of the new node is less than the node
// then this is the position to insert
if (seq_num < itr->seqNum)
found = true;
// Else go to next node
else
itr++;
}
// If the execution tick of the new node is greater than the node then
// go to the next node
else
itr++;
}
readyList.insert(itr, ready_node);
// Update the stat for max size reached of the readyList
maxReadyListSize = std::max<double>(readyList.size(),
maxReadyListSize.value());
}
void
TraceCPU::ElasticDataGen::printReadyList() {
auto itr = readyList.begin();
if (itr == readyList.end()) {
DPRINTF(TraceCPUData, "readyList is empty.\n");
return;
}
DPRINTF(TraceCPUData, "Printing readyList:\n");
while (itr != readyList.end()) {
auto graph_itr = depGraph.find(itr->seqNum);
GraphNode* node_ptr M5_VAR_USED = graph_itr->second;
DPRINTFR(TraceCPUData, "\t%lld(%s), %lld\n", itr->seqNum,
node_ptr->typeToStr(), itr->execTick);
itr++;
}
}
TraceCPU::ElasticDataGen::HardwareResource::HardwareResource(
uint16_t max_rob, uint16_t max_stores, uint16_t max_loads)
: sizeROB(max_rob),
sizeStoreBuffer(max_stores),
sizeLoadBuffer(max_loads),
oldestInFlightRobNum(UINT64_MAX),
numInFlightLoads(0),
numInFlightStores(0)
{}
void
TraceCPU::ElasticDataGen::HardwareResource::occupy(const GraphNode* new_node)
{
// Occupy ROB entry for the issued node
// Merely maintain the oldest node, i.e. numerically least robNum by saving
// it in the variable oldestInFLightRobNum.
inFlightNodes[new_node->seqNum] = new_node->robNum;
oldestInFlightRobNum = inFlightNodes.begin()->second;
// Occupy Load/Store Buffer entry for the issued node if applicable
if (new_node->isLoad()) {
++numInFlightLoads;
} else if (new_node->isStore()) {
++numInFlightStores;
} // else if it is a non load/store node, no buffer entry is occupied
printOccupancy();
}
void
TraceCPU::ElasticDataGen::HardwareResource::release(const GraphNode* done_node)
{
assert(!inFlightNodes.empty());
DPRINTFR(TraceCPUData, "\tClearing done seq. num %d from inFlightNodes..\n",
done_node->seqNum);
assert(inFlightNodes.find(done_node->seqNum) != inFlightNodes.end());
inFlightNodes.erase(done_node->seqNum);
if (inFlightNodes.empty()) {
// If we delete the only in-flight node and then the
// oldestInFlightRobNum is set to it's initialized (max) value.
oldestInFlightRobNum = UINT64_MAX;
} else {
// Set the oldest in-flight node rob number equal to the first node in
// the inFlightNodes since that will have the numerically least value.
oldestInFlightRobNum = inFlightNodes.begin()->second;
}
DPRINTFR(TraceCPUData, "\tCleared. inFlightNodes.size() = %d, "
"oldestInFlightRobNum = %d\n", inFlightNodes.size(),
oldestInFlightRobNum);
// A store is considered complete when a request is sent, thus ROB entry is
// freed. But it occupies an entry in the Store Buffer until its response
// is received. A load is considered complete when a response is received,
// thus both ROB and Load Buffer entries can be released.
if (done_node->isLoad()) {
assert(numInFlightLoads != 0);
--numInFlightLoads;
}
// For normal writes, we send the requests out and clear a store buffer
// entry on response. For writes which are strictly ordered, for e.g.
// writes to device registers, we do that within release() which is called
// when node is executed and taken off from readyList.
if (done_node->isStore() && done_node->isStrictlyOrdered()) {
releaseStoreBuffer();
}
}
void
TraceCPU::ElasticDataGen::HardwareResource::releaseStoreBuffer()
{
assert(numInFlightStores != 0);
--numInFlightStores;
}
bool
TraceCPU::ElasticDataGen::HardwareResource::isAvailable(
const GraphNode* new_node) const
{
uint16_t num_in_flight_nodes;
if (inFlightNodes.empty()) {
num_in_flight_nodes = 0;
DPRINTFR(TraceCPUData, "\t\tChecking resources to issue seq. num %lli:"
" #in-flight nodes = 0", new_node->seqNum);
} else if (new_node->robNum > oldestInFlightRobNum) {
// This is the intuitive case where new dep-free node is younger
// instruction than the oldest instruction in-flight. Thus we make sure
// in_flight_nodes does not overflow.
num_in_flight_nodes = new_node->robNum - oldestInFlightRobNum;
DPRINTFR(TraceCPUData, "\t\tChecking resources to issue seq. num %lli:"
" #in-flight nodes = %d - %d = %d", new_node->seqNum,
new_node->robNum, oldestInFlightRobNum, num_in_flight_nodes);
} else {
// This is the case where an instruction older than the oldest in-
// flight instruction becomes dep-free. Thus we must have already
// accounted for the entry in ROB for this new dep-free node.
// Immediately after this check returns true, oldestInFlightRobNum will
// be updated in occupy(). We simply let this node issue now.
num_in_flight_nodes = 0;
DPRINTFR(TraceCPUData, "\t\tChecking resources to issue seq. num %lli:"
" new oldestInFlightRobNum = %d, #in-flight nodes ignored",
new_node->seqNum, new_node->robNum);
}
DPRINTFR(TraceCPUData, ", LQ = %d/%d, SQ = %d/%d.\n",
numInFlightLoads, sizeLoadBuffer,
numInFlightStores, sizeStoreBuffer);
// Check if resources are available to issue the specific node
if (num_in_flight_nodes >= sizeROB) {
return false;
}
if (new_node->isLoad() && numInFlightLoads >= sizeLoadBuffer) {
return false;
}
if (new_node->isStore() && numInFlightStores >= sizeStoreBuffer) {
return false;
}
return true;
}
bool
TraceCPU::ElasticDataGen::HardwareResource::awaitingResponse() const {
// Return true if there is at least one read or write request in flight
return (numInFlightStores != 0 || numInFlightLoads != 0);
}
void
TraceCPU::ElasticDataGen::HardwareResource::printOccupancy() {
DPRINTFR(TraceCPUData, "oldestInFlightRobNum = %d, "
"LQ = %d/%d, SQ = %d/%d.\n",
oldestInFlightRobNum,
numInFlightLoads, sizeLoadBuffer,
numInFlightStores, sizeStoreBuffer);
}
void
TraceCPU::FixedRetryGen::regStats()
{
using namespace Stats;
numSendAttempted
.name(name() + ".numSendAttempted")
.desc("Number of first attempts to send a request")
;
numSendSucceeded
.name(name() + ".numSendSucceeded")
.desc("Number of successful first attempts")
;
numSendFailed
.name(name() + ".numSendFailed")
.desc("Number of failed first attempts")
;
numRetrySucceeded
.name(name() + ".numRetrySucceeded")
.desc("Number of successful retries")
;
instLastTick
.name(name() + ".instLastTick")
.desc("Last tick simulated from the fixed inst trace")
;
}
Tick
TraceCPU::FixedRetryGen::init()
{
DPRINTF(TraceCPUInst, "Initializing instruction fetch request generator"
" IcacheGen: fixed issue with retry.\n");
if (nextExecute()) {
DPRINTF(TraceCPUInst, "\tFirst tick = %d.\n", currElement.tick);
return currElement.tick;
} else {
panic("Read of first message in the trace failed.\n");
return MaxTick;
}
}
bool
TraceCPU::FixedRetryGen::tryNext()
{
// If there is a retry packet, try to send it
if (retryPkt) {
DPRINTF(TraceCPUInst, "Trying to send retry packet.\n");
if (!port.sendTimingReq(retryPkt)) {
// Still blocked! This should never occur.
DPRINTF(TraceCPUInst, "Retry packet sending failed.\n");
return false;
}
++numRetrySucceeded;
} else {
DPRINTF(TraceCPUInst, "Trying to send packet for currElement.\n");
// try sending current element
assert(currElement.isValid());
++numSendAttempted;
if (!send(currElement.addr, currElement.blocksize,
currElement.cmd, currElement.flags, currElement.pc)) {
DPRINTF(TraceCPUInst, "currElement sending failed.\n");
++numSendFailed;
// return false to indicate not to schedule next event
return false;
} else {
++numSendSucceeded;
}
}
// If packet was sent successfully, either retryPkt or currElement, return
// true to indicate to schedule event at current Tick plus delta. If packet
// was sent successfully and there is no next packet to send, return false.
DPRINTF(TraceCPUInst, "Packet sent successfully, trying to read next "
"element.\n");
retryPkt = nullptr;
// Read next element into currElement, currElement gets cleared so save the
// tick to calculate delta
Tick last_tick = currElement.tick;
if (nextExecute()) {
assert(currElement.tick >= last_tick);
delta = currElement.tick - last_tick;
}
return !traceComplete;
}
void
TraceCPU::FixedRetryGen::exit()
{
trace.reset();
}
bool
TraceCPU::FixedRetryGen::nextExecute()
{
if (traceComplete)
// We are at the end of the file, thus we have no more messages.
// Return false.
return false;
//Reset the currElement to the default values
currElement.clear();
// Read the next line to get the next message. If that fails then end of
// trace has been reached and traceComplete needs to be set in addition
// to returning false. If successful then next message is in currElement.
if (!trace.read(&currElement)) {
traceComplete = true;
instLastTick = curTick();
return false;
}
DPRINTF(TraceCPUInst, "inst fetch: %c addr %d pc %#x size %d tick %d\n",
currElement.cmd.isRead() ? 'r' : 'w',
currElement.addr,
currElement.pc,
currElement.blocksize,
currElement.tick);
return true;
}
bool
TraceCPU::FixedRetryGen::send(Addr addr, unsigned size, const MemCmd& cmd,
Request::FlagsType flags, Addr pc)
{
// Create new request
auto req = std::make_shared<Request>(addr, size, flags, masterID);
req->setPC(pc);
// If this is not done it triggers assert in L1 cache for invalid contextId
req->setContext(ContextID(0));
// Embed it in a packet
PacketPtr pkt = new Packet(req, cmd);
uint8_t* pkt_data = new uint8_t[req->getSize()];
pkt->dataDynamic(pkt_data);
if (cmd.isWrite()) {
memset(pkt_data, 0xA, req->getSize());
}
// Call MasterPort method to send a timing request for this packet
bool success = port.sendTimingReq(pkt);
if (!success) {
// If it fails, save the packet to retry when a retry is signalled by
// the cache
retryPkt = pkt;
}
return success;
}
void
TraceCPU::icacheRetryRecvd()
{
// Schedule an event to go through the control flow in the same tick as
// retry is received
DPRINTF(TraceCPUInst, "Icache retry received. Scheduling next IcacheGen"
" event @%lli.\n", curTick());
schedule(icacheNextEvent, curTick());
}
void
TraceCPU::dcacheRetryRecvd()
{
// Schedule an event to go through the execute flow in the same tick as
// retry is received
DPRINTF(TraceCPUData, "Dcache retry received. Scheduling next DcacheGen"
" event @%lli.\n", curTick());
schedule(dcacheNextEvent, curTick());
}
void
TraceCPU::schedDcacheNextEvent(Tick when)
{
if (!dcacheNextEvent.scheduled()) {
DPRINTF(TraceCPUData, "Scheduling next DcacheGen event at %lli.\n",
when);
schedule(dcacheNextEvent, when);
++numSchedDcacheEvent;
} else if (when < dcacheNextEvent.when()) {
DPRINTF(TraceCPUData, "Re-scheduling next dcache event from %lli"
" to %lli.\n", dcacheNextEvent.when(), when);
reschedule(dcacheNextEvent, when);
}
}
bool
TraceCPU::IcachePort::recvTimingResp(PacketPtr pkt)
{
// All responses on the instruction fetch side are ignored. Simply delete
// the packet to free allocated memory
delete pkt;
return true;
}
void
TraceCPU::IcachePort::recvReqRetry()
{
owner->icacheRetryRecvd();
}
void
TraceCPU::dcacheRecvTimingResp(PacketPtr pkt)
{
DPRINTF(TraceCPUData, "Received timing response from Dcache.\n");
dcacheGen.completeMemAccess(pkt);
}
bool
TraceCPU::DcachePort::recvTimingResp(PacketPtr pkt)
{
// Handle the responses for data memory requests which is done inside the
// elastic data generator
owner->dcacheRecvTimingResp(pkt);
// After processing the response delete the packet to free
// memory
delete pkt;
return true;
}
void
TraceCPU::DcachePort::recvReqRetry()
{
owner->dcacheRetryRecvd();
}
TraceCPU::ElasticDataGen::InputStream::InputStream(
const std::string& filename,
const double time_multiplier)
: trace(filename),
timeMultiplier(time_multiplier),
microOpCount(0)
{
// Create a protobuf message for the header and read it from the stream
ProtoMessage::InstDepRecordHeader header_msg;
if (!trace.read(header_msg)) {
panic("Failed to read packet header from %s\n", filename);
if (header_msg.tick_freq() != SimClock::Frequency) {
panic("Trace %s was recorded with a different tick frequency %d\n",
header_msg.tick_freq());
}
} else {
// Assign window size equal to the field in the trace that was recorded
// when the data dependency trace was captured in the o3cpu model
windowSize = header_msg.window_size();
}
}
void
TraceCPU::ElasticDataGen::InputStream::reset()
{
trace.reset();
}
bool
TraceCPU::ElasticDataGen::InputStream::read(GraphNode* element)
{
ProtoMessage::InstDepRecord pkt_msg;
if (trace.read(pkt_msg)) {
// Required fields
element->seqNum = pkt_msg.seq_num();
element->type = pkt_msg.type();
// Scale the compute delay to effectively scale the Trace CPU frequency
element->compDelay = pkt_msg.comp_delay() * timeMultiplier;
// Repeated field robDepList
element->clearRobDep();
assert((pkt_msg.rob_dep()).size() <= element->maxRobDep);
for (int i = 0; i < (pkt_msg.rob_dep()).size(); i++) {
element->robDep[element->numRobDep] = pkt_msg.rob_dep(i);
element->numRobDep += 1;
}
// Repeated field
element->clearRegDep();
assert((pkt_msg.reg_dep()).size() <= TheISA::MaxInstSrcRegs);
for (int i = 0; i < (pkt_msg.reg_dep()).size(); i++) {
// There is a possibility that an instruction has both, a register
// and order dependency on an instruction. In such a case, the
// register dependency is omitted
bool duplicate = false;
for (int j = 0; j < element->numRobDep; j++) {
duplicate |= (pkt_msg.reg_dep(i) == element->robDep[j]);
}
if (!duplicate) {
element->regDep[element->numRegDep] = pkt_msg.reg_dep(i);
element->numRegDep += 1;
}
}
// Optional fields
if (pkt_msg.has_p_addr())
element->physAddr = pkt_msg.p_addr();
else
element->physAddr = 0;
if (pkt_msg.has_v_addr())
element->virtAddr = pkt_msg.v_addr();
else
element->virtAddr = 0;
if (pkt_msg.has_size())
element->size = pkt_msg.size();
else
element->size = 0;
if (pkt_msg.has_flags())
element->flags = pkt_msg.flags();
else
element->flags = 0;
if (pkt_msg.has_pc())
element->pc = pkt_msg.pc();
else
element->pc = 0;
// ROB occupancy number
++microOpCount;
if (pkt_msg.has_weight()) {
microOpCount += pkt_msg.weight();
}
element->robNum = microOpCount;
return true;
}
// We have reached the end of the file
return false;
}
bool
TraceCPU::ElasticDataGen::GraphNode::removeRegDep(NodeSeqNum reg_dep)
{
for (auto& own_reg_dep : regDep) {
if (own_reg_dep == reg_dep) {
// If register dependency is found, make it zero and return true
own_reg_dep = 0;
assert(numRegDep > 0);
--numRegDep;
DPRINTFR(TraceCPUData, "\tFor %lli: Marking register dependency %lli "
"done.\n", seqNum, reg_dep);
return true;
}
}
// Return false if the dependency is not found
return false;
}
bool
TraceCPU::ElasticDataGen::GraphNode::removeRobDep(NodeSeqNum rob_dep)
{
for (auto& own_rob_dep : robDep) {
if (own_rob_dep == rob_dep) {
// If the rob dependency is found, make it zero and return true
own_rob_dep = 0;
assert(numRobDep > 0);
--numRobDep;
DPRINTFR(TraceCPUData, "\tFor %lli: Marking ROB dependency %lli "
"done.\n", seqNum, rob_dep);
return true;
}
}
return false;
}
void
TraceCPU::ElasticDataGen::GraphNode::clearRegDep() {
for (auto& own_reg_dep : regDep) {
own_reg_dep = 0;
}
numRegDep = 0;
}
void
TraceCPU::ElasticDataGen::GraphNode::clearRobDep() {
for (auto& own_rob_dep : robDep) {
own_rob_dep = 0;
}
numRobDep = 0;
}
bool
TraceCPU::ElasticDataGen::GraphNode::removeDepOnInst(NodeSeqNum done_seq_num)
{
// If it is an rob dependency then remove it
if (!removeRobDep(done_seq_num)) {
// If it is not an rob dependency then it must be a register dependency
// If the register dependency is not found, it violates an assumption
// and must be caught by assert.
bool regdep_found M5_VAR_USED = removeRegDep(done_seq_num);
assert(regdep_found);
}
// Return true if the node is dependency free
return (numRobDep == 0 && numRegDep == 0);
}
void
TraceCPU::ElasticDataGen::GraphNode::writeElementAsTrace() const
{
DPRINTFR(TraceCPUData, "%lli", seqNum);
DPRINTFR(TraceCPUData, ",%s", typeToStr());
if (isLoad() || isStore()) {
DPRINTFR(TraceCPUData, ",%i", physAddr);
DPRINTFR(TraceCPUData, ",%i", size);
DPRINTFR(TraceCPUData, ",%i", flags);
}
DPRINTFR(TraceCPUData, ",%lli", compDelay);
int i = 0;
DPRINTFR(TraceCPUData, "robDep:");
while (robDep[i] != 0) {
DPRINTFR(TraceCPUData, ",%lli", robDep[i]);
i++;
}
i = 0;
DPRINTFR(TraceCPUData, "regDep:");
while (regDep[i] != 0) {
DPRINTFR(TraceCPUData, ",%lli", regDep[i]);
i++;
}
auto child_itr = dependents.begin();
DPRINTFR(TraceCPUData, "dependents:");
while (child_itr != dependents.end()) {
DPRINTFR(TraceCPUData, ":%lli", (*child_itr)->seqNum);
child_itr++;
}
DPRINTFR(TraceCPUData, "\n");
}
std::string
TraceCPU::ElasticDataGen::GraphNode::typeToStr() const
{
return Record::RecordType_Name(type);
}
TraceCPU::FixedRetryGen::InputStream::InputStream(const std::string& filename)
: trace(filename)
{
// Create a protobuf message for the header and read it from the stream
ProtoMessage::PacketHeader header_msg;
if (!trace.read(header_msg)) {
panic("Failed to read packet header from %s\n", filename);
if (header_msg.tick_freq() != SimClock::Frequency) {
panic("Trace %s was recorded with a different tick frequency %d\n",
header_msg.tick_freq());
}
}
}
void
TraceCPU::FixedRetryGen::InputStream::reset()
{
trace.reset();
}
bool
TraceCPU::FixedRetryGen::InputStream::read(TraceElement* element)
{
ProtoMessage::Packet pkt_msg;
if (trace.read(pkt_msg)) {
element->cmd = pkt_msg.cmd();
element->addr = pkt_msg.addr();
element->blocksize = pkt_msg.size();
element->tick = pkt_msg.tick();
element->flags = pkt_msg.has_flags() ? pkt_msg.flags() : 0;
element->pc = pkt_msg.has_pc() ? pkt_msg.pc() : 0;
return true;
}
// We have reached the end of the file
return false;
}