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authorSteve Reinhardt <stever@eecs.umich.edu>2007-07-22 21:43:38 -0700
committerSteve Reinhardt <stever@eecs.umich.edu>2007-07-22 21:43:38 -0700
commit82e2a3557672864f0ea3ae64dad61681546aaf07 (patch)
tree1f0b74fe61274972525694ef6ad4bfbcb8b60231 /src/mem
parentfe442f67adad74130bb496061f2e13a993bdfcdd (diff)
downloadgem5-82e2a3557672864f0ea3ae64dad61681546aaf07.tar.xz
Replace lowerMSHRPending flag with more robust scheme
based on following Packet senderState links. --HG-- extra : convert_revision : 9027d59bd7242aa0e4275bf94d8b1fb27bd59d79
Diffstat (limited to 'src/mem')
-rw-r--r--src/mem/cache/cache.hh3
-rw-r--r--src/mem/cache/cache_impl.hh22
-rw-r--r--src/mem/cache/miss/mshr.cc48
-rw-r--r--src/mem/cache/miss/mshr.hh5
-rw-r--r--src/mem/cache/miss/mshr_queue.cc16
-rw-r--r--src/mem/packet.hh3
6 files changed, 60 insertions, 37 deletions
diff --git a/src/mem/cache/cache.hh b/src/mem/cache/cache.hh
index 7dfe9e8f1..57028a05e 100644
--- a/src/mem/cache/cache.hh
+++ b/src/mem/cache/cache.hh
@@ -190,8 +190,7 @@ class Cache : public BaseCache
* @param new_state The new coherence state for the block.
*/
void handleSnoop(PacketPtr ptk, BlkType *blk,
- bool is_timing, bool is_deferred,
- bool lower_mshr_pending);
+ bool is_timing, bool is_deferred);
/**
* Create a writeback request for the given block.
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index 82410afe1..efd7f4588 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -754,7 +754,7 @@ Cache<TagStore>::handleResponse(PacketPtr pkt)
} else {
// response to snoop request
DPRINTF(Cache, "processing deferred snoop...\n");
- handleSnoop(target->pkt, blk, true, true, false);
+ handleSnoop(target->pkt, blk, true, true);
}
mshr->popTarget();
@@ -917,8 +917,7 @@ Cache<TagStore>::doTimingSupplyResponse(PacketPtr req_pkt,
template<class TagStore>
void
Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk,
- bool is_timing, bool is_deferred,
- bool lower_mshr_pending)
+ bool is_timing, bool is_deferred)
{
assert(pkt->isRequest());
@@ -930,9 +929,6 @@ Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk,
if (is_timing) {
Packet *snoopPkt = new Packet(pkt, true); // clear flags
snoopPkt->setExpressSnoop();
- if (lower_mshr_pending) {
- snoopPkt->setLowerMSHRPending();
- }
snoopPkt->senderState = new ForwardResponseRecord(pkt, this);
cpuSidePort->sendTiming(snoopPkt);
if (snoopPkt->memInhibitAsserted()) {
@@ -1019,16 +1015,6 @@ Cache<TagStore>::snoopTiming(PacketPtr pkt)
Addr blk_addr = pkt->getAddr() & ~(Addr(blkSize-1));
MSHR *mshr = mshrQueue.findMatch(blk_addr);
- // If a lower cache has an operation on this block pending (not
- // yet in service) on the MSHR, then the upper caches need to know
- // about it, as this means that the pending operation logically
- // succeeds the current snoop. It's not sufficient to record
- // whether the MSHR *is* in service, as this misses the window
- // where the lower cache has completed the request and the
- // response is on its way back up the hierarchy.
- bool lower_mshr_pending =
- (mshr && (!mshr->inService) || pkt->lowerMSHRPending());
-
// Let the MSHR itself track the snoop and decide whether we want
// to go ahead and do the regular cache snoop
if (mshr && mshr->handleSnoop(pkt, order++)) {
@@ -1075,7 +1061,7 @@ Cache<TagStore>::snoopTiming(PacketPtr pkt)
}
}
- handleSnoop(pkt, blk, true, false, lower_mshr_pending);
+ handleSnoop(pkt, blk, true, false);
}
@@ -1090,7 +1076,7 @@ Cache<TagStore>::snoopAtomic(PacketPtr pkt)
}
BlkType *blk = tags->findBlock(pkt->getAddr());
- handleSnoop(pkt, blk, false, false, false);
+ handleSnoop(pkt, blk, false, false);
return hitLatency;
}
diff --git a/src/mem/cache/miss/mshr.cc b/src/mem/cache/miss/mshr.cc
index b9dfdf729..9b05aea3f 100644
--- a/src/mem/cache/miss/mshr.cc
+++ b/src/mem/cache/miss/mshr.cc
@@ -63,7 +63,8 @@ MSHR::TargetList::TargetList()
inline void
-MSHR::TargetList::add(PacketPtr pkt, Tick readyTime, Counter order, bool cpuSide)
+MSHR::TargetList::add(PacketPtr pkt, Tick readyTime,
+ Counter order, bool cpuSide)
{
if (cpuSide) {
if (pkt->needsExclusive()) {
@@ -73,6 +74,12 @@ MSHR::TargetList::add(PacketPtr pkt, Tick readyTime, Counter order, bool cpuSide
if (pkt->cmd == MemCmd::UpgradeReq) {
hasUpgrade = true;
}
+
+ MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
+ if (mshr != NULL) {
+ assert(!mshr->downstreamPending);
+ mshr->downstreamPending = true;
+ }
}
push_back(Target(pkt, readyTime, order, cpuSide));
@@ -98,6 +105,20 @@ MSHR::TargetList::replaceUpgrades()
void
+MSHR::TargetList::clearDownstreamPending()
+{
+ Iterator end_i = end();
+ for (Iterator i = begin(); i != end_i; ++i) {
+ MSHR *mshr = dynamic_cast<MSHR*>(i->pkt->senderState);
+ if (mshr != NULL) {
+ assert(mshr->downstreamPending);
+ mshr->downstreamPending = false;
+ }
+ }
+}
+
+
+void
MSHR::allocate(Addr _addr, int _size, PacketPtr target,
Tick whenReady, Counter _order)
{
@@ -109,6 +130,7 @@ MSHR::allocate(Addr _addr, int _size, PacketPtr target,
isCacheFill = false;
_isUncacheable = target->req->isUncacheable();
inService = false;
+ downstreamPending = false;
threadNum = 0;
ntargets = 1;
// Don't know of a case where we would allocate a new MSHR for a
@@ -121,6 +143,28 @@ MSHR::allocate(Addr _addr, int _size, PacketPtr target,
data = NULL;
}
+
+bool
+MSHR::markInService()
+{
+ assert(!inService);
+ if (isSimpleForward()) {
+ // we just forwarded the request packet & don't expect a
+ // response, so get rid of it
+ assert(getNumTargets() == 1);
+ popTarget();
+ return true;
+ }
+ inService = true;
+ if (!downstreamPending) {
+ // let upstream caches know that the request has made it to a
+ // level where it's going to get a response
+ targets->clearDownstreamPending();
+ }
+ return false;
+}
+
+
void
MSHR::deallocate()
{
@@ -164,7 +208,7 @@ MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
bool
MSHR::handleSnoop(PacketPtr pkt, Counter _order)
{
- if (!inService || (pkt->isExpressSnoop() && pkt->lowerMSHRPending())) {
+ if (!inService || downstreamPending) {
// 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
diff --git a/src/mem/cache/miss/mshr.hh b/src/mem/cache/miss/mshr.hh
index 06ef6e113..e850a8633 100644
--- a/src/mem/cache/miss/mshr.hh
+++ b/src/mem/cache/miss/mshr.hh
@@ -81,6 +81,7 @@ class MSHR : public Packet::SenderState
bool isReset() { return !needsExclusive && !hasUpgrade; }
void add(PacketPtr pkt, Tick readyTime, Counter order, bool cpuSide);
void replaceUpgrades();
+ void clearDownstreamPending();
};
/** A list of MSHRs. */
@@ -117,6 +118,8 @@ class MSHR : public Packet::SenderState
/** True if the request is uncacheable */
bool _isUncacheable;
+ bool downstreamPending;
+
bool pendingInvalidate;
bool pendingShared;
@@ -163,6 +166,8 @@ public:
void allocate(Addr addr, int size, PacketPtr pkt,
Tick when, Counter _order);
+ bool markInService();
+
/**
* Mark this MSHR as free.
*/
diff --git a/src/mem/cache/miss/mshr_queue.cc b/src/mem/cache/miss/mshr_queue.cc
index 4d3cf30e1..50a28fb3c 100644
--- a/src/mem/cache/miss/mshr_queue.cc
+++ b/src/mem/cache/miss/mshr_queue.cc
@@ -179,20 +179,12 @@ MSHRQueue::moveToFront(MSHR *mshr)
void
MSHRQueue::markInService(MSHR *mshr)
{
- assert(!mshr->inService);
- if (mshr->isSimpleForward()) {
- // we just forwarded the request packet & don't expect a
- // response, so get rid of it
- assert(mshr->getNumTargets() == 1);
- mshr->popTarget();
+ if (mshr->markInService()) {
deallocate(mshr);
- return;
+ } else {
+ readyList.erase(mshr->readyIter);
+ inServiceEntries += 1;
}
- mshr->inService = true;
- readyList.erase(mshr->readyIter);
- //mshr->readyIter = NULL;
- inServiceEntries += 1;
- //readyList.pop_front();
}
void
diff --git a/src/mem/packet.hh b/src/mem/packet.hh
index 779ea49a2..036bd3fd7 100644
--- a/src/mem/packet.hh
+++ b/src/mem/packet.hh
@@ -257,7 +257,6 @@ class Packet : public FastAlloc
Shared,
// Special control flags
ExpressSnoop,
- LowerMSHRPending, // not yet in service
NUM_PACKET_FLAGS
};
@@ -323,8 +322,6 @@ class Packet : public FastAlloc
// Special control flags
void setExpressSnoop() { flags[ExpressSnoop] = true; }
bool isExpressSnoop() { return flags[ExpressSnoop]; }
- void setLowerMSHRPending() { flags[LowerMSHRPending] = true; }
- bool lowerMSHRPending() { return flags[LowerMSHRPending]; }
// Network error conditions... encapsulate them as methods since
// their encoding keeps changing (from result field to command