Replace DeferredSnoop flag with LowerMSHRPending flag.

Turns out DeferredSnoop isn't quite the right bit of info
we needed... see new comment in cache_impl.hh.

--HG--
extra : convert_revision : a38de8c1677a37acafb743b7074ef88b21d3b7be
This commit is contained in:
Steve Reinhardt 2007-07-22 08:09:24 -07:00
parent 1edd143b68
commit 1c2d5f5e64
4 changed files with 26 additions and 13 deletions

View file

@ -190,7 +190,8 @@ class Cache : public BaseCache
* @param new_state The new coherence state for the block.
*/
void handleSnoop(PacketPtr ptk, BlkType *blk,
bool is_timing, bool is_deferred);
bool is_timing, bool is_deferred,
bool lower_mshr_pending);
/**
* Create a writeback request for the given block.

View file

@ -754,7 +754,7 @@ Cache<TagStore>::handleResponse(PacketPtr pkt)
} else {
// response to snoop request
DPRINTF(Cache, "processing deferred snoop...\n");
handleSnoop(target->pkt, blk, true, true);
handleSnoop(target->pkt, blk, true, true, false);
}
mshr->popTarget();
@ -917,7 +917,8 @@ Cache<TagStore>::doTimingSupplyResponse(PacketPtr req_pkt,
template<class TagStore>
void
Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk,
bool is_timing, bool is_deferred)
bool is_timing, bool is_deferred,
bool lower_mshr_pending)
{
assert(pkt->isRequest());
@ -929,8 +930,8 @@ Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk,
if (is_timing) {
Packet *snoopPkt = new Packet(pkt, true); // clear flags
snoopPkt->setExpressSnoop();
if (is_deferred) {
snoopPkt->setDeferredSnoop();
if (lower_mshr_pending) {
snoopPkt->setLowerMSHRPending();
}
snoopPkt->senderState = new ForwardResponseRecord(pkt, this);
cpuSidePort->sendTiming(snoopPkt);
@ -1017,8 +1018,19 @@ Cache<TagStore>::snoopTiming(PacketPtr pkt)
Addr blk_addr = pkt->getAddr() & ~(Addr(blkSize-1));
MSHR *mshr = mshrQueue.findMatch(blk_addr);
// better not be snooping a request that conflicts with something
// we have outstanding...
// If a lower cache has an operation on this block pending (not
// yet in service) on the MSHR, then the upper caches need to know
// about it, as this means that the pending operation logically
// succeeds the current snoop. It's not sufficient to record
// whether the MSHR *is* in service, as this misses the window
// where the lower cache has completed the request and the
// response is on its way back up the hierarchy.
bool lower_mshr_pending =
(mshr && (!mshr->inService) || pkt->lowerMSHRPending());
// Let the MSHR itself track the snoop and decide whether we want
// to go ahead and do the regular cache snoop
if (mshr && mshr->handleSnoop(pkt, order++)) {
DPRINTF(Cache, "Deferring snoop on in-service MSHR to blk %x\n",
blk_addr);
@ -1063,7 +1075,7 @@ Cache<TagStore>::snoopTiming(PacketPtr pkt)
}
}
handleSnoop(pkt, blk, true, false);
handleSnoop(pkt, blk, true, false, lower_mshr_pending);
}
@ -1078,7 +1090,7 @@ Cache<TagStore>::snoopAtomic(PacketPtr pkt)
}
BlkType *blk = tags->findBlock(pkt->getAddr());
handleSnoop(pkt, blk, false, false);
handleSnoop(pkt, blk, false, false, false);
return hitLatency;
}

View file

@ -164,7 +164,7 @@ MSHR::allocateTarget(PacketPtr pkt, Tick whenReady, Counter _order)
bool
MSHR::handleSnoop(PacketPtr pkt, Counter _order)
{
if (!inService || (pkt->isExpressSnoop() && !pkt->isDeferredSnoop())) {
if (!inService || (pkt->isExpressSnoop() && pkt->lowerMSHRPending())) {
// Request has not been issued yet, or it's been issued
// locally but is buffered unissued at some downstream cache
// which is forwarding us this snoop. Either way, the packet

View file

@ -257,7 +257,7 @@ class Packet : public FastAlloc
Shared,
// Special control flags
ExpressSnoop,
DeferredSnoop,
LowerMSHRPending, // not yet in service
NUM_PACKET_FLAGS
};
@ -323,8 +323,8 @@ class Packet : public FastAlloc
// Special control flags
void setExpressSnoop() { flags[ExpressSnoop] = true; }
bool isExpressSnoop() { return flags[ExpressSnoop]; }
void setDeferredSnoop() { flags[DeferredSnoop] = true; }
bool isDeferredSnoop() { return flags[DeferredSnoop]; }
void setLowerMSHRPending() { flags[LowerMSHRPending] = true; }
bool lowerMSHRPending() { return flags[LowerMSHRPending]; }
// Network error conditions... encapsulate them as methods since
// their encoding keeps changing (from result field to command