This patch fixes the MESI_Three_Level protocols so that it correctly
informers the Ruby sequencer when a line eviction occurs. Furthermore,
the patch allows the protocol to recognize the 'Store_Conditional'
RubyRequestType and shortcuts this operation if the monitored line
has been cleared from the address monitor. This prevents certain
livelock behaviour in which a line could ping-pong between competing
cores.
The patch establishes a new C/C++ preprocessor definition which allows
the Sequencer to send the 'Store_Conditional' RubyRequestType to
MESI_Three_Level instead of 'ST'. This is a temporary measure until
the other protocols explicitely recognize 'Store_Conditional'.
Change-Id: I27ae041ab0e015a4f54f20df666f9c4873c7583d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28328
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
The implementation for load-linked/store-conditional did not work
correctly for multi-core simulations. Since load-links were treated as
stores, it was not possible for a line to have multiple readers which
often resulted in livelock when using these instructions to implemented
mutexes. This improved implementation treats load-linked instructions
similarly to loads but locks the line after a copy has been fetched
locally. Writes to a monitored address ensure the 'linked' property is
blown away and any subsequent store-conditional will fail.
Change-Id: I19bd74459e26732c92c8b594901936e6439fb073
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27103
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
The MESI_Three_Level protocol includes a transition in its L1
definition to invalidate an SM state but this transition does
not notify the L0 cache. The unintended side effect of this
allows stale values to be read by the L0 cache. This can cause
incorrect behaviour when executing LL/SC based mutexes. This
patch ensures that all invalidates to SM states are exposed to
the L0 cache.
Change-Id: I7fefabdaa8027fdfa4c9c362abd7e467493196aa
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28047
Reviewed-by: John Alsop <johnathan.alsop@amd.com>
Reviewed-by: Pouya Fotouhi <pfotouhi@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
This patch addresses multiple cases:
- When a controller has read/write permissions while others have read
only permissions, the one with r/w permissions performs the read as
the others may have stale data
- When controllers only have lines with stale or busy access permissions,
a valid copy of the line may be in a message in transit in the network
or in a message buffer (not seen by the controller yet). In this case,
we forward the functional request accordingly.
- Sequencer messages should not accept functional reads
- Functional writes also update the packet data on the sequencer
outstanding request lists and the cpu-side response queue.
Change-Id: I6b0656f1a2b81d41bdcf6c783dfa522a77393981
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22022
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: John Alsop <johnathan.alsop@amd.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Calls to queueMemoryRead and queueMemoryWrite do not consider the size
of the queue between ruby directories and DRAMCtrl which causes infinite
buffering in the queued port between the two. This adds a MessageBuffer
in between which uses enqueues in SLICC and is therefore size checked
before any SLICC transaction pushing to the buffer can occur, removing
the infinite buffering between the two.
Change-Id: Iedb9070844e4f6c8532a9c914d126105ec98d0bc
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27427
Tested-by: Gem5 Cloud Project GCB service account <345032938727@cloudbuild.gserviceaccount.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bradford Beckmann <brad.beckmann@amd.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Bradford Beckmann <brad.beckmann@amd.com>
Add support in Ruby to use all replacement policies in Classic.
Furthermore, if new replacement policies are added to the
Classic system, the Ruby system will recognize new policies
without any other changes in Ruby system. The following list
all the major changes:
* Make Ruby cache entries (AbstractCacheEntry) inherit from
Classic cache entries (ReplaceableEntry). By doing this,
replacement policies can use cache entries from Ruby caches.
AccessPermission and print function are moved from
AbstractEntry to AbstractCacheEntry, so AbstractEntry is no
longer needed.
* DirectoryMemory and all SLICC files are changed to use
AbstractCacheEntry as their cache entry interface. So do the
python files in mem/slicc/ast which check the entry
interface.
* "main='false'" argument is added to the protocol files where
the DirectoryEntry is defined. This change helps
differentiate DirectoryEntry from CacheEntry because they are
both the instances of AbstractCacheEntry now.
* Use BaseReplacementPolicy in Ruby caches instead of
AbstractReplacementPolicy so that Ruby caches will recognize
the replacement policies from Classic.
* Add getLastAccess() and useOccupancy() function to Classic
system so that Ruby caches can use them. Move lastTouchTick
to ReplacementData struct because it's needed by
getLastAccess() to return the correct value.
* Add a 2-dimensional array of ReplacementData in Ruby caches
to store information for different replacement policies. Note
that, unlike Classic caches, where policy information is
stored in cache entries, the policy information needs to be
stored in a new 2-dimensional array. This is due to Ruby
caches deleting the cache entry every time the corresponding
cache line get evicted.
Change-Id: Idff6fdd2102a552c103e9d5f31f779aae052943f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20879
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The cacheProbe() function will return the victim entry, and it gets
called for multiple times in trigger function in a single miss. This
will cause a problem when we try to add a new replacement policy to
the Ruby system. Certain policy, like RRIP, will modify the block
information every time the getVictim() function gets called. To
prevent future problems, we need to store the victim entry, so that
we only call it once in one miss.
Change-Id: Ic5ca05f789d9bbfb963b8e993ef707020f243702
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21099
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Pouya Fotouhi <pfotouhi@ucdavis.edu>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>
