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mem-cache: Ensure that responses get data from the right source

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This CL makes sure that we use the right source for data for
responses after a response from the cache below.

Change-Id: I7329f3e6bcb7ce2054e912eb9dea48c9d169d45a
Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23667
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Nikos Nikoleris
2019-11-07 10:50:36 +00:00
parent 3001388ae1
commit 96e8f2ed3c
1 changed files with 31 additions and 14 deletions
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45
src/mem/cache/cache.cc vendored
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@@ -756,7 +756,14 @@ Cache::serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt, CacheBlk *blk)
assert(blk->isWritable());
}
if (blk && blk->isValid() && !mshr->isForward) {
// Here we decide whether we will satisfy the target using
// data from the block or from the response. We use the
// block data to satisfy the request when the block is
// present and valid and in addition the response in not
// forwarding data to the cache above (we didn't fill
// either); otherwise we use the packet data.
if (blk && blk->isValid() &&
(!mshr->isForward || !pkt->hasData())) {
satisfyRequest(tgt_pkt, blk, true, mshr->hasPostDowngrade());
// How many bytes past the first request is this one
@@ -791,15 +798,15 @@ Cache::serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt, CacheBlk *blk)
pkt->payloadDelay;
tgt_pkt->req->setExtraData(0);
} else {
// We are about to send a response to a cache above
// that asked for an invalidation; we need to
// invalidate our copy immediately as the most
// up-to-date copy of the block will now be in the
// cache above. It will also prevent this cache from
// responding (if the block was previously dirty) to
// snoops as they should snoop the caches above where
// they will get the response from.
if (is_invalidate && blk && blk->isValid()) {
// We are about to send a response to a cache above
// that asked for an invalidation; we need to
// invalidate our copy immediately as the most
// up-to-date copy of the block will now be in the
// cache above. It will also prevent this cache from
// responding (if the block was previously dirty) to
// snoops as they should snoop the caches above where
// they will get the response from.
invalidateBlock(blk);
}
// not a cache fill, just forwarding response
@@ -807,12 +814,22 @@ Cache::serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt, CacheBlk *blk)
// from lower level cahces/memory to the core.
completion_time += clockEdge(responseLatency) +
pkt->payloadDelay;
if (pkt->isRead() && !is_error) {
// sanity check
assert(pkt->matchAddr(tgt_pkt));
assert(pkt->getSize() >= tgt_pkt->getSize());
if (!is_error) {
if (pkt->isRead()) {
// sanity check
assert(pkt->matchAddr(tgt_pkt));
assert(pkt->getSize() >= tgt_pkt->getSize());
tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
} else {
// MSHR targets can read data either from the
// block or the response pkt. If we can't get data
// from the block (i.e., invalid or has old data)
// or the response (did not bring in any data)
// then make sure that the target didn't expect
// any.
assert(!tgt_pkt->hasRespData());
}
}
// this response did not allocate here and therefore