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MEM: Do not forward uncacheable to bus snoopers

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This patch adds a guarding if-statement to avoid forwarding
uncacheable requests (or rather their corresponding request packets)
to bus snoopers. These packets should never have any effect on the
caches, and thus there is no need to forward them to the snoopers.
This commit is contained in:
Andreas Hansson 2012-05-08 05:15:52 -04:00
parent 15e28c5ba6
commit 692351ea34
1 changed files with 22 additions and 9 deletions
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31
src/mem/bus.cc
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@ -217,9 +217,12 @@ Bus::recvTimingReq(PacketPtr pkt)
Tick headerFinishTime = pkt->isExpressSnoop() ? 0 : calcPacketTiming(pkt);
Tick packetFinishTime = pkt->isExpressSnoop() ? 0 : pkt->finishTime;
// the packet is a memory-mapped request and should be
// broadcasted to our snoopers but the source
forwardTiming(pkt, pkt->getSrc());
// uncacheable requests need never be snooped
if (!pkt->req->isUncacheable()) {
// the packet is a memory-mapped request and should be
// broadcasted to our snoopers but the source
forwardTiming(pkt, pkt->getSrc());
}
// remember if we add an outstanding req so we can undo it if
// necessary, if the packet needs a response, we should add it
@ -543,10 +546,17 @@ Bus::recvAtomic(PacketPtr pkt)
slavePorts[pkt->getSrc()]->name(), pkt->getAddr(),
pkt->cmdString());
// forward to all snoopers but the source
std::pair<MemCmd, Tick> snoop_result = forwardAtomic(pkt, pkt->getSrc());
MemCmd snoop_response_cmd = snoop_result.first;
Tick snoop_response_latency = snoop_result.second;
MemCmd snoop_response_cmd = MemCmd::InvalidCmd;
Tick snoop_response_latency = 0;
// uncacheable requests need never be snooped
if (!pkt->req->isUncacheable()) {
// forward to all snoopers but the source
std::pair<MemCmd, Tick> snoop_result =
forwardAtomic(pkt, pkt->getSrc());
snoop_response_cmd = snoop_result.first;
snoop_response_latency = snoop_result.second;
}
// even if we had a snoop response, we must continue and also
// perform the actual request at the destination
@ -643,8 +653,11 @@ Bus::recvFunctional(PacketPtr pkt)
pkt->cmdString());
}
// forward to all snoopers but the source
forwardFunctional(pkt, pkt->getSrc());
// uncacheable requests need never be snooped
if (!pkt->req->isUncacheable()) {
// forward to all snoopers but the source
forwardFunctional(pkt, pkt->getSrc());
}
// there is no need to continue if the snooping has found what we
// were looking for and the packet is already a response