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mem: Always use InvalidateReq to service WriteLineReq misses

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Previously, a WriteLineReq that missed in a cache would send out an
InvalidateReq if the block lookup failed or an UpgradeReq if the
block lookup succeeded but the block had sharers. This changes ensures
that a WriteLineReq always sends an InvalidateReq to invalidate all
copies of the block and satisfy the WriteLineReq.

Change-Id: I207ff5b267663abf02bc0b08aeadde69ad81be61
Reviewed-by: Andreas Hansson <andreas.hansson@arm.com>
This commit is contained in:
Nikos Nikoleris 2016-12-05 16:48:25 -05:00
parent 3172501a59
commit 78a97b1847
1 changed files with 7 additions and 6 deletions
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13
src/mem/cache/cache.cc vendored
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@ -924,7 +924,13 @@ Cache::createMissPacket(PacketPtr cpu_pkt, CacheBlk *blk,
// write miss on a shared owned block will generate a ReadExcl,
// which will clobber the owned copy.
const bool useUpgrades = true;
if (blkValid && useUpgrades) {
if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
assert(!blkValid || !blk->isWritable());
// forward as invalidate to all other caches, this gives us
// the line in Exclusive state, and invalidates all other
// copies
cmd = MemCmd::InvalidateReq;
} else if (blkValid && useUpgrades) {
// only reason to be here is that blk is read only and we need
// it to be writable
assert(needsWritable);
@ -937,11 +943,6 @@ Cache::createMissPacket(PacketPtr cpu_pkt, CacheBlk *blk,
// where the determination the StoreCond fails is delayed due to
// all caches not being on the same local bus.
cmd = MemCmd::SCUpgradeFailReq;
} else if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
// forward as invalidate to all other caches, this gives us
// the line in Exclusive state, and invalidates all other
// copies
cmd = MemCmd::InvalidateReq;
} else {
// block is invalid
cmd = needsWritable ? MemCmd::ReadExReq :