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authorAndreas Hansson <andreas.hansson@arm.com>2015-09-25 06:45:52 -0400
committerAndreas Hansson <andreas.hansson@arm.com>2015-09-25 06:45:52 -0400
commit3bd78a141ec60ae65d910286c3d99ae7030ba703 (patch)
tree32351d239e872bdc6c8f81ce200c05e41898b1bc
parent40fcb59c5440054f43675fd60ad8244c851f5050 (diff)
downloadgem5-3bd78a141ec60ae65d910286c3d99ae7030ba703.tar.xz
mem: Do not include snoop-filter latency in crossbar occupancy
This patch ensures that the snoop-filter latency only contributes to the packet latency, and not to the crossbar throughput/occupancy. In essence we treat the snoop-filter lookup as pipelined.
-rw-r--r--src/mem/coherent_xbar.cc12
1 files changed, 7 insertions, 5 deletions
diff --git a/src/mem/coherent_xbar.cc b/src/mem/coherent_xbar.cc
index 9e5407981..52f69e0c9 100644
--- a/src/mem/coherent_xbar.cc
+++ b/src/mem/coherent_xbar.cc
@@ -192,11 +192,10 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID slave_port_id)
if (snoopFilter) {
// check with the snoop filter where to forward this packet
auto sf_res = snoopFilter->lookupRequest(pkt, *src_port);
- // If SnoopFilter is enabled, the total time required by a packet
- // to be delivered through the xbar has to be charged also with
- // to lookup latency of the snoop filter (sf_res.second).
+ // the time required by a packet to be delivered through
+ // the xbar has to be charged also with to lookup latency
+ // of the snoop filter
pkt->headerDelay += sf_res.second * clockPeriod();
- packetFinishTime += sf_res.second * clockPeriod();
DPRINTF(CoherentXBar, "recvTimingReq: src %s %s 0x%x"\
" SF size: %i lat: %i\n", src_port->name(),
pkt->cmdString(), pkt->getAddr(), sf_res.first.size(),
@@ -384,7 +383,10 @@ CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id)
if (snoopFilter) {
// let the Snoop Filter work its magic and guide probing
auto sf_res = snoopFilter->lookupSnoop(pkt);
- // No timing here: packetFinishTime += sf_res.second * clockPeriod();
+ // the time required by a packet to be delivered through
+ // the xbar has to be charged also with to lookup latency
+ // of the snoop filter
+ pkt->headerDelay += sf_res.second * clockPeriod();
DPRINTF(CoherentXBar, "recvTimingSnoopReq: src %s %s 0x%x"\
" SF size: %i lat: %i\n", masterPorts[master_port_id]->name(),
pkt->cmdString(), pkt->getAddr(), sf_res.first.size(),