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-rw-r--r--src/mem/cache/cache_impl.hh4
-rw-r--r--src/mem/cache/miss/mshr.cc153
-rw-r--r--src/mem/cache/miss/mshr.hh35
3 files changed, 139 insertions, 53 deletions
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index b78360d4a..9fb5cdbde 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -836,7 +836,7 @@ Cache<TagStore>::handleFill(PacketPtr pkt, BlkType *blk,
// must be an outstanding upgrade request on block
// we're about to replace...
assert(!blk->isWritable());
- assert(repl_mshr->needsExclusive);
+ assert(repl_mshr->needsExclusive());
// too hard to replace block with transient state;
// just use temporary storage to complete the current
// request and then get rid of it
@@ -1177,7 +1177,7 @@ Cache<TagStore>::getTimingPacket()
pkt = tgt_pkt;
} else {
BlkType *blk = tags->findBlock(mshr->addr);
- pkt = getBusPacket(tgt_pkt, blk, mshr->needsExclusive);
+ pkt = getBusPacket(tgt_pkt, blk, mshr->needsExclusive());
mshr->isCacheFill = (pkt != NULL);
diff --git a/src/mem/cache/miss/mshr.cc b/src/mem/cache/miss/mshr.cc
index 7ba3789fe..856819c10 100644
--- a/src/mem/cache/miss/mshr.cc
+++ b/src/mem/cache/miss/mshr.cc
@@ -52,8 +52,51 @@ MSHR::MSHR()
inService = false;
ntargets = 0;
threadNum = -1;
+ targets = new TargetList();
+ deferredTargets = new TargetList();
}
+
+MSHR::TargetList::TargetList()
+ : needsExclusive(false), hasUpgrade(false)
+{}
+
+
+inline void
+MSHR::TargetList::add(PacketPtr pkt, Tick readyTime, Counter order, bool cpuSide)
+{
+ if (cpuSide) {
+ if (pkt->needsExclusive()) {
+ needsExclusive = true;
+ }
+
+ if (pkt->cmd == MemCmd::UpgradeReq) {
+ hasUpgrade = true;
+ }
+ }
+
+ push_back(Target(pkt, readyTime, order, cpuSide));
+}
+
+
+void
+MSHR::TargetList::replaceUpgrades()
+{
+ if (!hasUpgrade)
+ return;
+
+ Iterator end_i = end();
+ for (Iterator i = begin(); i != end_i; ++i) {
+ if (i->pkt->cmd == MemCmd::UpgradeReq) {
+ i->pkt->cmd = MemCmd::ReadExReq;
+ DPRINTF(Cache, "Replacing UpgradeReq with ReadExReq\n");
+ }
+ }
+
+ hasUpgrade = false;
+}
+
+
void
MSHR::allocate(Addr _addr, int _size, PacketPtr target,
Tick whenReady, Counter _order)
@@ -64,16 +107,15 @@ MSHR::allocate(Addr _addr, int _size, PacketPtr target,
order = _order;
assert(target);
isCacheFill = false;
- needsExclusive = target->needsExclusive();
_isUncacheable = target->req->isUncacheable();
inService = false;
threadNum = 0;
ntargets = 1;
// Don't know of a case where we would allocate a new MSHR for a
// snoop (mem-side request), so set cpuSide to true here.
- targets.push_back(Target(target, whenReady, _order, true));
- assert(deferredTargets.empty());
- deferredNeedsExclusive = false;
+ assert(targets->isReset());
+ targets->add(target, whenReady, _order, true);
+ assert(deferredTargets->isReset());
pendingInvalidate = false;
pendingShared = false;
data = NULL;
@@ -82,8 +124,9 @@ MSHR::allocate(Addr _addr, int _size, PacketPtr target,
void
MSHR::deallocate()
{
- assert(targets.empty());
- assert(deferredTargets.empty());
+ assert(targets->empty());
+ targets->resetFlags();
+ assert(deferredTargets->isReset());
assert(ntargets == 0);
inService = false;
//allocIter = NULL;
@@ -94,26 +137,25 @@ MSHR::deallocate()
* Adds a target to an MSHR
*/
void
-MSHR::allocateTarget(PacketPtr target, Tick whenReady, Counter _order)
+MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
{
- if (inService) {
- if (!deferredTargets.empty() || pendingInvalidate ||
- (!needsExclusive && target->needsExclusive())) {
- // need to put on deferred list
- deferredTargets.push_back(Target(target, whenReady, _order, true));
- if (target->needsExclusive()) {
- deferredNeedsExclusive = true;
- }
- } else {
- // still OK to append to outstanding request
- targets.push_back(Target(target, whenReady, _order, true));
- }
+ // if there's a request already in service for this MSHR, we will
+ // have to defer the new target until after the response if any of
+ // the following are true:
+ // - there are other targets already deferred
+ // - there's a pending invalidate to be applied after the response
+ // comes back (but before this target is processed)
+ // - the outstanding request is for a non-exclusive block and this
+ // target requires an exclusive block
+ if (inService &&
+ (!deferredTargets->empty() || pendingInvalidate ||
+ (!targets->needsExclusive && pkt->needsExclusive()))) {
+ // need to put on deferred list
+ deferredTargets->add(pkt, whenReady, _order, true);
} else {
- if (target->needsExclusive()) {
- needsExclusive = true;
- }
-
- targets.push_back(Target(target, whenReady, _order, true));
+ // no request outstanding, or still OK to append to
+ // outstanding request
+ targets->add(pkt, whenReady, _order, true);
}
++ntargets;
@@ -123,22 +165,50 @@ bool
MSHR::handleSnoop(PacketPtr pkt, Counter _order)
{
if (!inService || (pkt->isExpressSnoop() && !pkt->isDeferredSnoop())) {
+ // Request has not been issued yet, or it's been issued
+ // locally but is buffered unissued at some downstream cache
+ // which is forwarding us this snoop. Either way, the packet
+ // we're snooping logically precedes this MSHR's request, so
+ // the snoop has no impact on the MSHR, but must be processed
+ // in the standard way by the cache. The only exception is
+ // that if we're an L2+ cache buffering an UpgradeReq from a
+ // higher-level cache, and the snoop is invalidating, then our
+ // buffered upgrades must be converted to read exclusives,
+ // since the upper-level cache no longer has a valid copy.
+ // That is, even though the upper-level cache got out on its
+ // local bus first, some other invalidating transaction
+ // reached the global bus before the upgrade did.
+ if (pkt->needsExclusive()) {
+ targets->replaceUpgrades();
+ deferredTargets->replaceUpgrades();
+ }
+
return false;
}
+ // From here on down, the request issued by this MSHR logically
+ // precedes the request we're snooping.
+
+ if (pkt->needsExclusive()) {
+ // snooped request still precedes the re-request we'll have to
+ // issue for deferred targets, if any...
+ deferredTargets->replaceUpgrades();
+ }
+
if (pendingInvalidate) {
// a prior snoop has already appended an invalidation, so
- // logically we don't have the block anymore...
+ // logically we don't have the block anymore; no need for
+ // further snooping.
return true;
}
- if (needsExclusive || pkt->needsExclusive()) {
+ if (targets->needsExclusive || pkt->needsExclusive()) {
// actual target device (typ. PhysicalMemory) will delete the
// packet on reception, so we need to save a copy here
- targets.push_back(Target(new Packet(pkt), curTick, _order, false));
+ targets->add(new Packet(pkt), curTick, _order, false);
++ntargets;
- if (needsExclusive) {
+ if (targets->needsExclusive) {
// We're awaiting an exclusive copy, so ownership is pending.
// It's up to us to respond once the data arrives.
pkt->assertMemInhibit();
@@ -163,21 +233,25 @@ MSHR::handleSnoop(PacketPtr pkt, Counter _order)
bool
MSHR::promoteDeferredTargets()
{
- if (deferredTargets.empty()) {
+ assert(targets->empty());
+ if (deferredTargets->empty()) {
return false;
}
- assert(targets.empty());
+ // swap targets & deferredTargets lists
+ TargetList *tmp = targets;
targets = deferredTargets;
- deferredTargets.clear();
- assert(targets.size() == ntargets);
+ deferredTargets = tmp;
+
+ assert(targets->size() == ntargets);
+
+ // clear deferredTargets flags
+ deferredTargets->resetFlags();
- needsExclusive = deferredNeedsExclusive;
pendingInvalidate = false;
pendingShared = false;
- deferredNeedsExclusive = false;
- order = targets.front().order;
- readyTime = std::max(curTick, targets.front().readyTime);
+ order = targets->front().order;
+ readyTime = std::max(curTick, targets->front().readyTime);
return true;
}
@@ -202,16 +276,17 @@ MSHR::dump()
"Addr: %x ntargets %d\n"
"Targets:\n",
inService, threadNum, addr, ntargets);
-
- TargetListIterator tar_it = targets.begin();
+#if 0
+ TargetListIterator tar_it = targets->begin();
for (int i = 0; i < ntargets; i++) {
- assert(tar_it != targets.end());
+ assert(tar_it != targets->end());
ccprintf(cerr, "\t%d: Addr: %x cmd: %s\n",
i, tar_it->pkt->getAddr(), tar_it->pkt->cmdString());
tar_it++;
}
+#endif
ccprintf(cerr, "\n");
}
diff --git a/src/mem/cache/miss/mshr.hh b/src/mem/cache/miss/mshr.hh
index 9c6a8cf33..06ef6e113 100644
--- a/src/mem/cache/miss/mshr.hh
+++ b/src/mem/cache/miss/mshr.hh
@@ -68,10 +68,21 @@ class MSHR : public Packet::SenderState
{}
};
- /** Defines the Data structure of the MSHR targetlist. */
- typedef std::list<Target> TargetList;
- /** Target list iterator. */
- typedef std::list<Target>::iterator TargetListIterator;
+ class TargetList : public std::list<Target> {
+ /** Target list iterator. */
+ typedef std::list<Target>::iterator Iterator;
+
+ public:
+ bool needsExclusive;
+ bool hasUpgrade;
+
+ TargetList();
+ void resetFlags() { needsExclusive = hasUpgrade = false; }
+ bool isReset() { return !needsExclusive && !hasUpgrade; }
+ void add(PacketPtr pkt, Tick readyTime, Counter order, bool cpuSide);
+ void replaceUpgrades();
+ };
+
/** A list of MSHRs. */
typedef std::list<MSHR *> List;
/** MSHR list iterator. */
@@ -99,13 +110,13 @@ class MSHR : public Packet::SenderState
/** True if we will be putting the returned block in the cache */
bool isCacheFill;
+
/** True if we need to get an exclusive copy of the block. */
- bool needsExclusive;
+ bool needsExclusive() { return targets->needsExclusive; }
/** True if the request is uncacheable */
bool _isUncacheable;
- bool deferredNeedsExclusive;
bool pendingInvalidate;
bool pendingShared;
@@ -133,9 +144,9 @@ class MSHR : public Packet::SenderState
private:
/** List of all requests that match the address */
- TargetList targets;
+ TargetList *targets;
- TargetList deferredTargets;
+ TargetList *deferredTargets;
public:
@@ -179,19 +190,19 @@ public:
* Returns a pointer to the target list.
* @return a pointer to the target list.
*/
- TargetList* getTargetList() { return &targets; }
+ TargetList *getTargetList() { return targets; }
/**
* Returns true if there are targets left.
* @return true if there are targets
*/
- bool hasTargets() { return !targets.empty(); }
+ bool hasTargets() { return !targets->empty(); }
/**
* Returns a reference to the first target.
* @return A pointer to the first target.
*/
- Target *getTarget() { assert(hasTargets()); return &targets.front(); }
+ Target *getTarget() { assert(hasTargets()); return &targets->front(); }
/**
* Pop first target.
@@ -199,7 +210,7 @@ public:
void popTarget()
{
--ntargets;
- targets.pop_front();
+ targets->pop_front();
}
bool isSimpleForward()
generated by cgit v1.2.3 (git 2.25.1) at 2024-10-31 17:52:50 +0000