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-rw-r--r--src/mem/bus.cc50
1 files changed, 33 insertions, 17 deletions
diff --git a/src/mem/bus.cc b/src/mem/bus.cc
index d29422593..88b91983b 100644
--- a/src/mem/bus.cc
+++ b/src/mem/bus.cc
@@ -160,7 +160,7 @@ template <typename PortClass>
BaseBus::Layer<PortClass>::Layer(BaseBus& _bus, const std::string& _name) :
Drainable(),
bus(_bus), _name(_name), state(IDLE), drainManager(NULL),
- releaseEvent(this)
+ retryingPort(NULL), releaseEvent(this)
{
}
@@ -192,12 +192,17 @@ BaseBus::Layer<PortClass>::tryTiming(PortClass* port)
{
// first we see if the bus is busy, next we check if we are in a
// retry with a port other than the current one
- if (state == BUSY || (state == RETRY && port != retryList.front())) {
+ if (state == BUSY || (state == RETRY && port != retryingPort)) {
// put the port at the end of the retry list
retryList.push_back(port);
return false;
}
+ // @todo: here we should no longer consider this port retrying
+ // once we can differentiate retries due to a busy bus and a
+ // failed forwarding, for now keep it so we can stick it back at
+ // the front of the retry list if needed
+
// update the state which is shared for request, response and
// snoop responses, if we were idle we are now busy, if we are in
// a retry, then do not change
@@ -211,12 +216,13 @@ template <typename PortClass>
void
BaseBus::Layer<PortClass>::succeededTiming(Tick busy_time)
{
- // if a retrying port succeeded, also take it off the retry list
+ // if a retrying port succeeded, update the state and reset the
+ // retrying port
if (state == RETRY) {
- DPRINTF(BaseBus, "Remove retry from list %s\n",
- retryList.front()->name());
- retryList.pop_front();
+ DPRINTF(BaseBus, "Succeeded retry from %s\n",
+ retryingPort->name());
state = BUSY;
+ retryingPort = NULL;
}
// we should either have gone from idle to busy in the
@@ -231,10 +237,17 @@ template <typename PortClass>
void
BaseBus::Layer<PortClass>::failedTiming(PortClass* port, Tick busy_time)
{
- // if we are not in a retry, i.e. busy (but never idle), or we are
- // in a retry but not for the current port, then add the port at
- // the end of the retry list
- if (state != RETRY || port != retryList.front()) {
+ // if the current failing port is the retrying one, then for now stick it
+ // back at the front of the retry list to not change any regressions
+ if (state == RETRY) {
+ // we should never see a retry from any port but the current
+ // retry port at this point
+ assert(port == retryingPort);
+ retryList.push_front(port);
+ retryingPort = NULL;
+ } else {
+ // if we are not in a retry, i.e. busy (but never idle), then
+ // add the port at the end of the retry list
retryList.push_back(port);
}
@@ -283,25 +296,28 @@ BaseBus::Layer<PortClass>::retryWaiting()
// we always go to retrying from idle
assert(state == IDLE);
- // update the state which is shared for request, response and
- // snoop responses
+ // update the state
state = RETRY;
+ // set the retrying port to the front of the retry list and pop it
+ // off the list
+ assert(retryingPort == NULL);
+ retryingPort = retryList.front();
+ retryList.pop_front();
+
// note that we might have blocked on the receiving port being
// busy (rather than the bus itself) and now call retry before the
// destination called retry on the bus
- retryList.front()->sendRetry();
+ retryingPort->sendRetry();
// If the bus is still in the retry state, sendTiming wasn't
// called in zero time (e.g. the cache does this)
if (state == RETRY) {
- retryList.pop_front();
-
//Burn a cycle for the missed grant.
- // update the state which is shared for request, response and
- // snoop responses
+ // update the state to busy and reset the retrying port
state = BUSY;
+ retryingPort = NULL;
// occupy the bus layer until the next cycle ends
occupyLayer(bus.clockEdge(Cycles(1)));