diff options
| -rw-r--r-- | src/mem/cache/cache_impl.hh | 15 | ||||
| -rw-r--r-- | src/mem/cache/miss/mshr.cc | 1 | ||||
| -rw-r--r-- | src/mem/packet.hh | 8 |
3 files changed, 23 insertions, 1 deletions
diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh index 6db40b609..2ead54ba6 100644 --- a/src/mem/cache/cache_impl.hh +++ b/src/mem/cache/cache_impl.hh @@ -371,6 +371,17 @@ Cache<TagStore>::timingAccess(PacketPtr pkt) DPRINTF(Cache, "mem inhibited on 0x%x: not responding\n", pkt->getAddr()); assert(!pkt->req->isUncacheable()); + // Special tweak for multilevel coherence: snoop downward here + // on invalidates since there may be other caches below here + // that have shared copies. Not necessary if we know that + // supplier had exclusive copy to begin with. + if (pkt->needsExclusive() && !pkt->isSupplyExclusive()) { + Packet *snoopPkt = new Packet(pkt, true); // clear flags + snoopPkt->setExpressSnoop(); + snoopPkt->assertMemInhibit(); + memSidePort->sendTiming(snoopPkt); + // main memory will delete snoopPkt + } return true; } @@ -966,6 +977,7 @@ Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk, // we respond in atomic mode), so just figure out what to do now // and then do it later bool supply = blk->isDirty() && pkt->isRead() && !upperSupply; + bool have_exclusive = blk->isWritable(); bool invalidate = pkt->isInvalidate(); if (pkt->isRead() && !pkt->isInvalidate()) { @@ -985,6 +997,9 @@ Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk, if (supply) { assert(!pkt->memInhibitAsserted()); pkt->assertMemInhibit(); + if (have_exclusive) { + pkt->setSupplyExclusive(); + } if (is_timing) { doTimingSupplyResponse(pkt, blk->data, is_deferred); } else { diff --git a/src/mem/cache/miss/mshr.cc b/src/mem/cache/miss/mshr.cc index 7f216ad39..5ba3d1ec5 100644 --- a/src/mem/cache/miss/mshr.cc +++ b/src/mem/cache/miss/mshr.cc @@ -257,6 +257,7 @@ MSHR::handleSnoop(PacketPtr pkt, Counter _order) // We're awaiting an exclusive copy, so ownership is pending. // It's up to us to respond once the data arrives. pkt->assertMemInhibit(); + pkt->setSupplyExclusive(); } else { // Someone else may respond before we get around to // processing this snoop, which means the copied request diff --git a/src/mem/packet.hh b/src/mem/packet.hh index 036bd3fd7..c6534d6c9 100644 --- a/src/mem/packet.hh +++ b/src/mem/packet.hh @@ -256,7 +256,11 @@ class Packet : public FastAlloc MemInhibit, Shared, // Special control flags + /// Special timing-mode atomic snoop for multi-level coherence. ExpressSnoop, + /// Does supplier have exclusive copy? + /// Useful for multi-level coherence. + SupplyExclusive, NUM_PACKET_FLAGS }; @@ -315,13 +319,15 @@ class Packet : public FastAlloc // Snoop flags void assertMemInhibit() { flags[MemInhibit] = true; } - void assertShared() { flags[Shared] = true; } bool memInhibitAsserted() { return flags[MemInhibit]; } + void assertShared() { flags[Shared] = true; } bool sharedAsserted() { return flags[Shared]; } // Special control flags void setExpressSnoop() { flags[ExpressSnoop] = true; } bool isExpressSnoop() { return flags[ExpressSnoop]; } + void setSupplyExclusive() { flags[SupplyExclusive] = true; } + bool isSupplyExclusive() { return flags[SupplyExclusive]; } // Network error conditions... encapsulate them as methods since // their encoding keeps changing (from result field to command |