diff options
| -rw-r--r-- | src/mem/cache/cache_impl.hh | 35 | ||||
| -rw-r--r-- | src/mem/cache/mshr.cc | 5 | ||||
| -rw-r--r-- | src/mem/cache/mshr.hh | 11 |
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 + if (mshr) { + // Everything up to this point is obsolete, meaning + // they should not modify the cache.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isObsolete()) { + DPRINTF(Cache, "%s: skipping cache fills; data for %s of %x " + "is obsolete\n", __func__, pkt-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isObsolete()) { + DPRINTF(Cache, "%s: skipping satisfyCpuSideRequest; " + "data for %s of %x is obsolete\n", + __func__, target-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. */ |