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mem: Enforce strict use of busFirst- and busLastWordTime

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This patch adds a check to ensure that the delay incurred by
the bus is not simply disregarded, but accounted for by someone. At
this point, all the modules do is to zero it out, and no additional
time is spent. This highlights where the bus timing is simply dropped
instead of being paid for.

As a follow up, the locations identified in this patch should add this
additional time to the packets in one way or another. For now it
simply acts as a sanity check and highlights where the delay is simply
ignored.

Since no time is added, all regressions remain the same.
This commit is contained in:
Andreas Hansson
2013-02-19 05:56:06 -05:00
parent 40d0e6c899
commit 860155a5fc
10 changed files with 53 additions and 0 deletions
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20
src/mem/cache/cache_impl.hh vendored
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@@ -381,6 +381,8 @@ Cache<TagStore>::recvTimingSnoopResp(PacketPtr pkt)
pkt->setDest(rec->prevSrc);
delete rec;
// @todo someone should pay for this
pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
memSidePort->schedTimingSnoopResp(pkt, time);
}
@@ -419,6 +421,9 @@ Cache<TagStore>::recvTimingReq(PacketPtr pkt)
// supplier had exclusive copy to begin with.
if (pkt->needsExclusive() && !pkt->isSupplyExclusive()) {
Packet *snoopPkt = new Packet(pkt, true); // clear flags
// also reset the bus time that the original packet has
// not yet paid for
snoopPkt->busFirstWordDelay = snoopPkt->busLastWordDelay = 0;
snoopPkt->setExpressSnoop();
snoopPkt->assertMemInhibit();
memSidePort->sendTimingReq(snoopPkt);
@@ -437,6 +442,9 @@ Cache<TagStore>::recvTimingReq(PacketPtr pkt)
if (pkt->req->isUncacheable()) {
uncacheableFlush(pkt);
// @todo: someone should pay for this
pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
// writes go in write buffer, reads use MSHR
if (pkt->isWrite() && !pkt->isRead()) {
allocateWriteBuffer(pkt, time, true);
@@ -489,6 +497,8 @@ Cache<TagStore>::recvTimingReq(PacketPtr pkt)
if (needsResponse) {
pkt->makeTimingResponse();
// @todo: Make someone pay for this
pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
cpuSidePort->schedTimingResp(pkt, clockEdge(lat));
} else {
/// @todo nominally we should just delete the packet here,
@@ -499,6 +509,9 @@ Cache<TagStore>::recvTimingReq(PacketPtr pkt)
} else {
// miss
// @todo: Make someone pay for this
pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
Addr blk_addr = blockAlign(pkt->getAddr());
MSHR *mshr = mshrQueue.findMatch(blk_addr);
@@ -946,6 +959,8 @@ Cache<TagStore>::recvTimingResp(PacketPtr pkt)
// isInvalidate() set otherwise.
target->pkt->cmd = MemCmd::ReadRespWithInvalidate;
}
// reset the bus additional time as it is now accounted for
target->pkt->busFirstWordDelay = target->pkt->busLastWordDelay = 0;
cpuSidePort->schedTimingResp(target->pkt, completion_time);
break;
@@ -1250,6 +1265,8 @@ doTimingSupplyResponse(PacketPtr req_pkt, uint8_t *blk_data,
assert(req_pkt->isInvalidate() || pkt->sharedAsserted());
pkt->allocate();
pkt->makeTimingResponse();
// @todo Make someone pay for this
pkt->busFirstWordDelay = pkt->busLastWordDelay = 0;
if (pkt->isRead()) {
pkt->setDataFromBlock(blk_data, blkSize);
}
@@ -1293,6 +1310,9 @@ Cache<TagStore>::handleSnoop(PacketPtr pkt, BlkType *blk,
Packet snoopPkt(pkt, true); // clear flags
snoopPkt.setExpressSnoop();
snoopPkt.pushSenderState(new ForwardResponseRecord(pkt->getSrc()));
// the snoop packet does not need to wait any additional
// time
snoopPkt.busFirstWordDelay = snoopPkt.busLastWordDelay = 0;
cpuSidePort->sendTimingSnoopReq(&snoopPkt);
if (snoopPkt.memInhibitAsserted()) {
// cache-to-cache response from some upper cache