This patch enforces insertion order transmission of packets on the
response path in the cache. Note that the logic to enforce order is
already present in the packet queue, this patch simply turns it on for
queues in the response path.
Without this patch, there are corner cases where a request-response is
faster than a response-response forwarded through the cache. This
violation of queuing order causes problems in the snoop filter leaving
it with inaccurate information. This causes assert failures in the
snoop filter later on.
A follow on patch relaxes the order enforcement in the packet queue to
limit the performance impact.
This patch unifies how we deal with delayed packet deletion, where the
receiving slave is responsible for deleting the packet, but the
sending agent (e.g. a cache) is still relying on the pointer until the
call to sendTimingReq completes. Previously we used a mix of a
deletion vector and a construct using unique_ptr. With this patch we
ensure all slaves use the latter approach.
This patch addresses the upgrading of deferred targets in the MSHR,
and makes it clearer by explicitly calling out what is happening
(deferred targets are promoted if we get exclusivity without asking
for it).
This patch fixes issues in the interactions between deferred snoops
and WriteLineReq. More specifically, the patch addresses an issue
where deferred snoops caused assertion failures when being serviced on
the arrival of an InvalidateResp. The response packet was perceived to
be invalidating, when actually it is not for the cache that sent out
the original invalidation request.
This patch mirrors the logic in timing mode which sends up snoops to
check for cached copies before sending CleanEvicts and Writebacks down
the memory hierarchy. In case there is a copy in a cache above,
discard CleanEvicts and set the BLOCK_CACHED flag in Writebacks so
that writebacks do not reset the cache residency bit in the snoop
filter below.
This patch introduces the concept of a snoop latency. Given the
requirement to snoop and forward packets in zero time (due to the
coherency mechanism), the latency is accounted for later.
On a snoop, we establish the latency, and later add it to the header
delay of the packet. To allow multiple caches to contribute to the
snoop latency, we use a separate variable in the packet, and then take
the maximum before adding it to the header delay.
Cleaning up dead code. The CLREX stores zero directly to
MISCREG_LOCKFLAG and so the request flag is no longer needed. The
corresponding functionality in the cache tags is also removed.
Open up for other subclasses to BaseCache and transition to using the
explicit Cache subclass.
--HG--
rename : src/mem/cache/BaseCache.py => src/mem/cache/Cache.py
This patch changes the cache implementation to rely on virtual methods
rather than using the replacement policy as a template argument.
There is no impact on the simulation performance, and overall the
changes make it easier to modify (and subclass) the cache and/or
replacement policy.
this patch implements a new tags class that uses a random replacement policy.
these tags prefer to evict invalid blocks first, if none are available a
replacement candidate is chosen at random.
this patch factors out the common code in the LRU class and creates a new
abstract class: the BaseSetAssoc class. any set associative tag class must
implement the functionality related to the actual replacement policy in the
following methods:
accessBlock()
findVictim()
insertBlock()
invalidate()
The IIC replacement policy seems to be unused and has probably
gathered too much bit rot to be useful. This patch removes the IIC and
its associated cache parameters.
timing mode still broken.
configs/example/memtest.py:
Revamp options.
src/cpu/memtest/memtest.cc:
No need for memory initialization.
No need to make atomic response... memory system should do that now.
src/cpu/memtest/memtest.hh:
MemTest really doesn't want to snoop.
src/mem/bridge.cc:
checkFunctional() cleanup.
src/mem/bus.cc:
src/mem/bus.hh:
src/mem/cache/base_cache.cc:
src/mem/cache/base_cache.hh:
src/mem/cache/cache.cc:
src/mem/cache/cache.hh:
src/mem/cache/cache_blk.hh:
src/mem/cache/cache_builder.cc:
src/mem/cache/cache_impl.hh:
src/mem/cache/coherence/coherence_protocol.cc:
src/mem/cache/coherence/coherence_protocol.hh:
src/mem/cache/coherence/simple_coherence.hh:
src/mem/cache/miss/SConscript:
src/mem/cache/miss/mshr.cc:
src/mem/cache/miss/mshr.hh:
src/mem/cache/miss/mshr_queue.cc:
src/mem/cache/miss/mshr_queue.hh:
src/mem/cache/prefetch/base_prefetcher.cc:
src/mem/cache/tags/fa_lru.cc:
src/mem/cache/tags/fa_lru.hh:
src/mem/cache/tags/iic.cc:
src/mem/cache/tags/iic.hh:
src/mem/cache/tags/lru.cc:
src/mem/cache/tags/lru.hh:
src/mem/cache/tags/split.cc:
src/mem/cache/tags/split.hh:
src/mem/cache/tags/split_lifo.cc:
src/mem/cache/tags/split_lifo.hh:
src/mem/cache/tags/split_lru.cc:
src/mem/cache/tags/split_lru.hh:
src/mem/packet.cc:
src/mem/packet.hh:
src/mem/physical.cc:
src/mem/physical.hh:
src/mem/tport.cc:
More major reorg. Seems to work for atomic mode now,
timing mode still broken.
--HG--
extra : convert_revision : 7e70dfc4a752393b911880ff028271433855ae87
Compiles but doesn't work... committing just so I can merge
(stupid bk!).
src/mem/bridge.cc:
Get rid of SNOOP_COMMIT.
src/mem/bus.cc:
src/mem/packet.hh:
Get rid of SNOOP_COMMIT & two-pass snoop.
First bits of EXPRESS_SNOOP support.
src/mem/cache/base_cache.cc:
src/mem/cache/base_cache.hh:
src/mem/cache/cache.hh:
src/mem/cache/cache_impl.hh:
src/mem/cache/miss/blocking_buffer.cc:
src/mem/cache/miss/miss_queue.cc:
src/mem/cache/prefetch/base_prefetcher.cc:
Big reorg of ports and port-related functions & events.
src/mem/cache/cache.cc:
src/mem/cache/cache_builder.cc:
src/mem/cache/coherence/SConscript:
Get rid of UniCoherence object.
--HG--
extra : convert_revision : 7672434fa3115c9b1c94686f497e57e90413b7c3
