Implementation of a Second-Chance replacement policy. Similar to FIFO,
but every block is given a second chance if it has been touched.
Change-Id: Id4d52b698d0045a4914a4d848fdf9c3c00a28508
Reviewed-on: https://gem5-review.googlesource.com/9441
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Replacement data is specific for each replacement policy, and thus
should be instantiated differently by each policy.
Touch() and reset() do not need to be aware of CacheBlk, as they
only update its ReplacementData.
Invalidate() makes replacement policies independent of cache blocks,
by removing the awareness of the valid state.
An inheritable base ReplaceableEntry class was created to allow usage
of replacement policies with any table-like structure.
Change-Id: I998917d800fa48504ed95abffa2f1b7bfd68522b
Reviewed-on: https://gem5-review.googlesource.com/9421
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
With this patch a gem5 System will store more info about its Masters.
While it was previously keeping track of the Master name and Master ID
only, it is now adding a per-Master pointer to the SimObject related to
the Master.
This will make it possible for a client to query a System for a Master
using either the master's name or the master's pointer.
Change-Id: I8b97d328a65cd06f329e2cdd3679451c17d2b8f6
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9781
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Use block iteration instead of numSets and assoc in print(),
cleanupRefs() and computeStats().
This makes these functions rely solely on what they are used for:
printing and calculating stats of blocks. With the addition of
Sectors an extra indirection level is added, and thus these
functions would be skipping blocks.
Change-Id: I0006f82736cce02ba3e501ffafe9236f748daf32
Reviewed-on: https://gem5-review.googlesource.com/10143
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
An access must perform a block search, which is done by findBlock.
The tagHash is indexed by tags, so use extractTag instead of re-
implementing its functionality.
Change-Id: Ib5abacbc65cddf0f2d7e4440eb5355b56998a585
Reviewed-on: https://gem5-review.googlesource.com/10082
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
This change fixes a few bugs and refactors the mechanism by which
caches that use the FALRU tags can output statistics for multiple
cache sizes ranging from the minimum cache of interest up to the
actual configured cache size.
Change-Id: Ibea029cf275a8c068c26eceeb06c761fc53aede2
Reviewed-on: https://gem5-review.googlesource.com/9826
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
There are many devices that need to handle reads/writes of different
word sizes. A common pattern is a switch statement that check for the
size of a packet and then calls the corresponding
Packet::(get|set)<uintXX_t> methods. Simplify this by implementing
Packet::(get|set)UintX helper functions.
The getter reads a word of the size specified in the packet and the
specified endianness. The word is then zero-extended to 64
bits. Conversely, the setter truncates the word down to the size
required in the packet and then byte-swaps it to the desired
endianness.
Change-Id: I2f0c27fe3903abf3859bea13b07c7f5f0fb0809f
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9761
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Since a3177645, the MESI_Three_Level protocol does not build. This
changeset addresses the problem by adding the L0Cache machine type
to the static machine type declaration in Ruby's export file.
Change-Id: I6327547fcb34595619caeb73932c0032f5f65c9f
Reviewed-on: https://gem5-review.googlesource.com/8383
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
FALRU was missing MoveToTail functionality within its invalidate
function, and MoveToHead was doing unnecessary passes when the
moved block was the head already.
Besides, added some comments to make the code understandable.
Change-Id: I2430d82b5d53c88b102a62610ea38b46d6e03a55
Reviewed-on: https://gem5-review.googlesource.com/9541
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Block insertion is being done in the getCandidates function, while the
insertBlock function does not do anything.
Besides, BaseTags' stats weren't being updated.
Change-Id: Iadab9c1ea61519214f66fa24c4b91c4fc95604c0
Reviewed-on: https://gem5-review.googlesource.com/8882
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Replacement policies (LRU, Random) are currently considered as array
indexing methods, but have completely different functionalities:
- Array indexers determine the possible locations for block allocation.
This information is used to generate replacement candidates when
conflicts happen.
- Replacement policies determine which of the replacement candidates
should be evicted to make room for new allocations.
For this reason, they were split into different classes. Advantages:
- Easier and more straightforward to implement other replacement
policies (RRIP, LFU, ARC, ...)
- Allow easier future implementation of cache organization schemes
As now we can't assure the use of sets, the previous way to create a
true LRU is not viable. Now a timestamp_bits parameter controls how
many bits are dedicated for the timestamp, and a true LRU can be
achieved through an infinite number of bits (although a few bits suffice
in practice).
Change-Id: I23750db121f1474d17831137e6ff618beb2b3eda
Reviewed-on: https://gem5-review.googlesource.com/8501
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Block allocation can fail when there is an in-service MSHR that
operates on the victim block. This can happed due to:
* an upgrade operation: a request that needs a writable copy of the
block finds a shared (non-writable) copy of the block in the cache
and has allocates an MSHR for the pending upgrade operation, or
* a clean operation: a clean request finds a dirty copy of the block
and allocates an MSHR for the pending clean operation.
This changes relaxes an assertion to allow for the 2nd case (cache
clean operations).
Change-Id: Ib51482160b5f2b3702ed744b0eac2029d34bc9d4
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/9021
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
Only a small quantity of prefetches were issued, as the positive
feedback mechanism was not implemented. This commit adds a new
action po_observeHit, which notifies the RubyPrefetcher of
successful prefetches and resets the prefetch flag.
When a cache line was replaced by a prefetch, the wrong queue could
be stalled. This commit adds a new event PF_L1_Replacement, which
stalls the correct queue.
The behavior when receiving a prefetch or instruction fetch while
in PF_IS_I (prefetch caused GETs, but got invalidated before the
response was received) was undefined. This was changed to drop the
prefetch request or change the state to non-prefetch, respectively.
This behavior is analogous to IS_I (non-prefetch caused GETs, but
got invalidated before the response was received) and the data case,
respectively.
In my local branch a major (20+%) performance increase can be
observed in SPEC2006 gobmk and leslie3d when enabling the
prefetcher. Some other benchmarks like bwaves, GemsFDTD, sphinx and
wrf show smaller (~10%) performance increases. Unfortunately, the
performance in most other SPEC benchmarks is still poor, most likely
as the prefetcher does not detect strides fast/often enough. In
order to push the change timely (most benchmarks have runtimes in
the order of days on my machine even with the smallest parameters)
after checkout, I have only run gobmk with the base repository
+ this commit. The results match those of my local branch.
Change-Id: I9903a2fcd02060ea5e619b409f31f7d6fac47ae8
Reviewed-on: https://gem5-review.googlesource.com/8801
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Swapnil Haria <swapnilster@gmail.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
invalidate was defined as a separate function in the base associative
and fully-associative tags classes although both functions should
implement identical functionality. This patch moves the invalidate
function in the base tags class.
Change-Id: I206ee969b00ab9e05873c6d87531474fcd712907
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8286
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Starting with version 3, scons imposes using the print function instead
of the print statement in code it processes. To get things building
again, this change moves all python code within gem5 to use the
function version. Another change by another author separately made this
same change to the site_tools and site_init.py files.
Change-Id: I2de7dc3b1be756baad6f60574c47c8b7e80ea3b0
Reviewed-on: https://gem5-review.googlesource.com/8761
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
Writebacks write data to either an existing block or a newly allocated
block. In either case we need to populate the whenReady field of the
block which will determine when the new value can be used.
Change-Id: I5788fad0b8086a1be96714639bf6a9470b334926
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8285
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
The secure bit should be set when we fill a block with data from a
secure location, as indicated by the packet that triggers the fill.
This patch fixes a bug in which the cache wouldn't populate the secure
bit when filling the temp block.
Change-Id: I95c706146449804ff42b205b25dd79750f3e882a
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8284
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Since b8b13206c8, the '.fast' build has failed to compile with an error
caused by a variable and an assert.
As a reminder, assert macros are optimized out of the build for '.fast'.
If an assert check requires a variable that is unused anywhere else in
the code, the compiler complains that the variable is unused and the
scons build fails. The solution is to add a M5_VAR_USED specifier to
tell the compiler to ignore the variable.
Change-Id: I38f6bbed1e4c0506c5bbc1206c21f1f7e3d8dfe6
Reviewed-on: https://gem5-review.googlesource.com/8462
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>
