diff options
Diffstat (limited to 'src/mem/cache/cache.cc')
-rw-r--r-- | src/mem/cache/cache.cc | 36 |
1 files changed, 29 insertions, 7 deletions
diff --git a/src/mem/cache/cache.cc b/src/mem/cache/cache.cc index 3060c3e77..19d8dc800 100644 --- a/src/mem/cache/cache.cc +++ b/src/mem/cache/cache.cc @@ -1730,7 +1730,7 @@ Cache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data, memSidePort->schedTimingSnoopResp(pkt, forward_time, true); } -void +uint32_t Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, bool is_deferred, bool pending_inval) { @@ -1748,6 +1748,8 @@ Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, bool invalidate = pkt->isInvalidate(); bool M5_VAR_USED needs_exclusive = pkt->needsExclusive(); + uint32_t snoop_delay = 0; + if (forwardSnoops) { // first propagate snoop upward to see if anyone above us wants to // handle it. save & restore packet src since it will get @@ -1765,6 +1767,12 @@ Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, // time snoopPkt.headerDelay = snoopPkt.payloadDelay = 0; cpuSidePort->sendTimingSnoopReq(&snoopPkt); + + // add the header delay (including crossbar and snoop + // delays) of the upward snoop to the snoop delay for this + // cache + snoop_delay += snoopPkt.headerDelay; + if (snoopPkt.memInhibitAsserted()) { // cache-to-cache response from some upper cache assert(!alreadyResponded); @@ -1796,7 +1804,7 @@ Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, if (!blk || !blk->isValid()) { DPRINTF(Cache, "%s snoop miss for %s addr %#llx size %d\n", __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize()); - return; + return snoop_delay; } else { DPRINTF(Cache, "%s snoop hit for %s for addr %#llx size %d, " "old state is %s\n", __func__, pkt->cmdString(), @@ -1824,7 +1832,7 @@ Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, DPRINTF(Cache, "Found addr %#llx in upper level cache for snoop %s from" " lower cache\n", pkt->getAddr(), pkt->cmdString()); pkt->setBlockCached(); - return; + return snoop_delay; } if (!pkt->req->isUncacheable() && pkt->isRead() && !invalidate) { @@ -1884,6 +1892,8 @@ Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing, } DPRINTF(Cache, "new state is %s\n", blk->print()); + + return snoop_delay; } @@ -1907,6 +1917,14 @@ Cache::recvTimingSnoopReq(PacketPtr pkt) Addr blk_addr = blockAlign(pkt->getAddr()); MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure); + // Update the latency cost of the snoop so that the crossbar can + // account for it. Do not overwrite what other neighbouring caches + // have already done, rather take the maximum. The update is + // tentative, for cases where we return before an upward snoop + // happens below. + pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, + lookupLatency * clockPeriod()); + // Inform request(Prefetch, CleanEvict or Writeback) from below of // MSHR hit, set setBlockCached. if (mshr && pkt->mustCheckAbove()) { @@ -2004,7 +2022,12 @@ Cache::recvTimingSnoopReq(PacketPtr pkt) // We could be more selective and return here if the // request is non-exclusive or if the writeback is // exclusive. - handleSnoop(pkt, blk, true, false, false); + uint32_t snoop_delay = handleSnoop(pkt, blk, true, false, false); + + // Override what we did when we first saw the snoop, as we now + // also have the cost of the upwards snoops to account for + pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, snoop_delay + + lookupLatency * clockPeriod()); } bool @@ -2030,9 +2053,8 @@ Cache::recvAtomicSnoop(PacketPtr pkt) } CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure()); - handleSnoop(pkt, blk, false, false, false); - // We consider forwardLatency here because a snoop occurs in atomic mode - return forwardLatency * clockPeriod(); + uint32_t snoop_delay = handleSnoop(pkt, blk, false, false, false); + return snoop_delay + lookupLatency * clockPeriod(); } |