changeset 823a6aa11fbd in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=823a6aa11fbd
description:
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.
diffstat:
src/mem/coherent_xbar.cc | 12 +++++++-----
1 files changed, 7 insertions(+), 5 deletions(-)
diffs (30 lines):
diff -r f918d72dbc02 -r 823a6aa11fbd src/mem/coherent_xbar.cc
--- a/src/mem/coherent_xbar.cc Fri Sep 25 06:45:50 2015 -0400
+++ b/src/mem/coherent_xbar.cc Fri Sep 25 06:45:52 2015 -0400
@@ -192,11 +192,10 @@
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 @@
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(),
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