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mem: Filter cache snoops based on address ranges

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This patch adds a filter to the cache to drop snoop requests that are
not for a range covered by the cache. This fixes an issue observed
when multiple caches are placed in parallel, covering different
address ranges. Without this patch, all the caches will forward the
snoop upwards, when only one should do so.
This commit is contained in:
Andreas Hansson 2014-02-18 05:50:58 -05:00
parent bf2f178f85
commit 969b436243
1 changed files with 14 additions and 1 deletions
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15
src/mem/cache/cache_impl.hh vendored
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@ -1475,10 +1475,23 @@ Cache<TagStore>::recvTimingSnoopReq(PacketPtr pkt)
// Snoops shouldn't happen when bypassing caches
assert(!system->bypassCaches());
// check if the packet is for an address range covered by this
// cache, partly to not waste time looking for it, but also to
// ensure that we only forward the snoop upwards if it is within
// our address ranges
bool in_range = false;
for (AddrRangeList::const_iterator r = addrRanges.begin();
r != addrRanges.end(); ++r) {
if (r->contains(pkt->getAddr())) {
in_range = true;
break;
}
}
// Note that some deferred snoops don't have requests, since the
// original access may have already completed
if ((pkt->req && pkt->req->isUncacheable()) ||
pkt->cmd == MemCmd::Writeback) {
pkt->cmd == MemCmd::Writeback || !in_range) {
//Can't get a hit on an uncacheable address
//Revisit this for multi level coherence
return;