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-rw-r--r--src/mem/cache/cache_impl.hh35
-rw-r--r--src/mem/cache/mshr.cc5
-rw-r--r--src/mem/cache/mshr.hh11
3 files changed, 45 insertions, 6 deletions
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index 24e3eec15..4b51a6359 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -636,7 +636,20 @@ Cache<TagStore>::recvTimingReq(PacketPtr pkt)
pkt = pf;
}
- if (mshr) {
+ if (pkt && (pkt->cmd == MemCmd::WriteInvalidateReq)) {
+ // WriteInvalidates cannot coalesce with other requests, so
+ // we cannot use an existing MSHR. If one exists, we mark it
+ // as 'obsolete' so they don't modify the cache.
+ if (mshr) {
+ // Everything up to this point is obsolete, meaning
+ // they should not modify the cache.
+ DPRINTF(Cache, "%s: marking MSHR obsolete in %s of %x\n",
+ __func__, pkt->cmdString(), pkt->getAddr());
+
+ mshr->markObsolete();
+ }
+ allocateMissBuffer(pkt, time, true);
+ } else if (mshr) {
/// MSHR hit
/// @note writebacks will be checked in getNextMSHR()
/// for any conflicting requests to the same block
@@ -1077,7 +1090,10 @@ Cache<TagStore>::recvTimingResp(PacketPtr pkt)
bool is_fill = !mshr->isForward &&
(pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
- if (is_fill && !is_error) {
+ if (mshr->isObsolete()) {
+ DPRINTF(Cache, "%s: skipping cache fills; data for %s of %x "
+ "is obsolete\n", __func__, pkt->cmdString(), pkt->getAddr());
+ } else if (is_fill && !is_error) {
DPRINTF(Cache, "Block for addr %x being updated in Cache\n",
pkt->getAddr());
@@ -1113,8 +1129,19 @@ Cache<TagStore>::recvTimingResp(PacketPtr pkt)
}
if (is_fill) {
- satisfyCpuSideRequest(target->pkt, blk,
- true, mshr->hasPostDowngrade());
+ // Presently the only situation leading to 'obsolete'
+ // data is when a WriteInvalidate blows away an already
+ // pending/in-progress read. We don't want to overwrite
+ // cache data in that case.
+ if (mshr->isObsolete()) {
+ DPRINTF(Cache, "%s: skipping satisfyCpuSideRequest; "
+ "data for %s of %x is obsolete\n",
+ __func__, target->pkt->cmdString(),
+ target->pkt->getAddr());
+ } else {
+ satisfyCpuSideRequest(target->pkt, blk,
+ true, mshr->hasPostDowngrade());
+ }
// How many bytes past the first request is this one
int transfer_offset =
target->pkt->getOffset(blkSize) - initial_offset;
diff --git a/src/mem/cache/mshr.cc b/src/mem/cache/mshr.cc
index 79a91da2b..fcf9fc425 100644
--- a/src/mem/cache/mshr.cc
+++ b/src/mem/cache/mshr.cc
@@ -62,8 +62,8 @@
using namespace std;
MSHR::MSHR() : readyTime(0), _isUncacheable(false), downstreamPending(false),
- pendingDirty(false), postInvalidate(false),
- postDowngrade(false), queue(NULL), order(0), addr(0), size(0),
+ pendingDirty(false), postInvalidate(false), postDowngrade(false),
+ _isObsolete(false), queue(NULL), order(0), addr(0), size(0),
isSecure(false), inService(false), isForward(false),
threadNum(InvalidThreadID), data(NULL)
{
@@ -214,6 +214,7 @@ MSHR::allocate(Addr _addr, int _size, PacketPtr target, Tick whenReady,
_isUncacheable = target->req->isUncacheable();
inService = false;
downstreamPending = false;
+ _isObsolete = false;
threadNum = 0;
assert(targets.isReset());
// Don't know of a case where we would allocate a new MSHR for a
diff --git a/src/mem/cache/mshr.hh b/src/mem/cache/mshr.hh
index 65357b9e6..9ea9cfb2c 100644
--- a/src/mem/cache/mshr.hh
+++ b/src/mem/cache/mshr.hh
@@ -89,6 +89,9 @@ class MSHR : public Packet::SenderState, public Printable
/** Did we snoop a read while waiting for data? */
bool postDowngrade;
+ /** Did we get WriteInvalidate'd (and therefore obsoleted)? */
+ bool _isObsolete;
+
public:
class Target {
@@ -214,6 +217,8 @@ class MSHR : public Packet::SenderState, public Printable
bool isUncacheable() const { return _isUncacheable; }
+ bool isObsolete() const { return _isObsolete; }
+
/**
* Allocate a miss to this MSHR.
* @param cmd The requesting command.
@@ -289,6 +294,12 @@ class MSHR : public Packet::SenderState, public Printable
bool checkFunctional(PacketPtr pkt);
+ /** Mark this MSHR as tracking a transaction with obsoleted data. It still
+ * needs to complete its lifecycle, but should not modify the cache. */
+ void markObsolete() {
+ _isObsolete = true;
+ }
+
/**
* Prints the contents of this MSHR for debugging.
*/