This patch adds supports for using the "classic" prefetchers with ruby
cache controllers.
This pull request includes a few commits making the changes in this
order:
- Refactor decouples the classic cache and prefetchers interfaces
- Extras probes for later integration with ruby
- General ruby-side support
- Adds support for the CHI protocol
Commit [mem-ruby: support prefetcher in CHI
protocol](2bdb65653b)
may be used as example on how to add support for other protocols.
JIRA issues that may be related to this pull request:
https://gem5.atlassian.net/browse/GEM5-457https://gem5.atlassian.net/browse/GEM5-1112
hasBeenPrefetched can now take a requestor id and returns true only if
the block was prefetched by a prefetcher with the same id. This may be
necessary to properly train multiple prefetchers attached to the same
cache. If returns true if the block was prefetched by any prefetcher
when the id is not provided.
Related JIRA:
https://gem5.atlassian.net/browse/GEM5-457https://gem5.atlassian.net/browse/GEM5-1112
Change-Id: I205e000fd5ff100e5a5d24d88bca7c6a46689ab2
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Remove the prefetch_on_access and prefetch_on_pf_hit from BaseCache.
BasePrefetch no longer expects this params to exist in the parent.
Configurations that set these parameter using the cache object were
fixed.
Change-Id: I9ab6a545eaf930ee41ebda74e2b6b8bad0ca35a7
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
This patches decouples the prefetchers from the cache implementation
as the first step to allow using the classic prefetchers with ruby
caches. The prefetchers that need do cache lookups can do so using
the accessor object provided when the probes are notified. This may
also facilitate connecting the same prefetcher to multiple caches.
Related JIRA:
https://gem5.atlassian.net/browse/GEM5-457https://gem5.atlassian.net/browse/GEM5-1112
Change-Id: I4fee1a3613ae009fabf45d7b747e4582cad315ef
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
This commit optimizes the address generation logic in the strided
prefetcher by introducing the following changes
(d is the degree of the prefetcher)
* Evaluate the fixed prefetch_stride only once (and not d-times)
* Replace 2d multiplications (d * prefetch_stride and distance *
prefetch_stride) with additions by updating the new base prefetch
address while looping
Change-Id: I49c52333fc4c7071ac3d73443f2ae07bfcd5b8e4
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-by: Tiberiu Bucur <tiberiu.bucur@arm.com>
The Stride Prefetcher will skip this number of strides ahead of the
first identified prefetch, then generate `degree` prefetches at
`stride` intervals. A value of zero indicates no skip (i.e. start
prefetching from the next identified prefetch address).
This parameter can be used to increase the timeliness of prefetches by
starting to prefetch far enough ahead of the demand stream to cover
the memory system latency.
[Richard Cooper <richard.cooper@arm.com>:
- Added detail to commit comment and `distance` Param documentation.
- Changed `distance` Param from `Param.Int` to `Param.Unsigned`.
]
Change-Id: I6c4e744079b53a7b804d8eab93b0f07b566f0c08
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Signed-off-by: Richard Cooper <richard.cooper@arm.com>
pkt->req->isCacheMaintenance() would not include a check
for clean eviction before notifying the prefetcher,
causing gem5 to crash.
Change-Id: I1d082a87a3908b1ed46c5d632d45d8b09950b382
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Prefetch queue entries were being squashed by comparing the address
of each queued prefetch against the block address of the demand
access. Only prefetches that happen to fall on a cache-line block
boundary would be squashed.
This patch converts the prefetch addresses to block addresses before
comparison.
Change-Id: I55ecb4919e94ad314b91c7795bba257c550b1528
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
To find a candidate in cache base.cc, function getPacket
is called. In case of multi-prefetchers, we alyways start
from the first prefetcher. Given the default value for "latency"
is 1, there is always a candidate ready for prefech by prefetcher 0.
Hence, we need an arbitration mechansim to cycle through
all prefechers. To make this fair, we added a variable to save what
prefetcher first used to get a packet from, and in the next round,
we start from the next prefetcher to give every prefetcher a chance
to be the first one in a round-robin fashion.
JIRA Ticket: https://gem5.atlassian.net/browse/GEM5-1169
Change-Id: I1c6a267b2bf71764559a080371c1d7f8be95ac71
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/56265
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Daniel Carvalho <odanrc@yahoo.com.br>
Tested-by: kokoro <noreply+kokoro@google.com>
When calling a method in a superclass, you can/should use the super()
method to get a reference to that class. The python 2 version of that
method takes two parameters, the current class name, and the "self"
instance. The python 3 version takes no arguments. This is better for a
at least three reasons.
First, this version is less verbose because you don't have to specify
any arguments.
Second, you don't have to remember which argument goes where (I always
have to look it up), and you can't accidentally use the wrong class
name, or forget to update it if you copy code from a different class.
Third, this version will work correctly if you use a class decorator.
I don't know exactly how the mechanics of this work, but it is referred
to in a comment on this stackoverflow question:
https://stackoverflow.com/questions/681953/how-to-decorate-a-class
Change-Id: I427737c8f767e80da86cd245642e3b057121bc3b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52224
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This parameter is used to figure out if two addresses are on the same or
different pages, and could be used to find what page they were on and
the page offset, although it doesn't look like the later two are
actually used.
This value could possibly come from the TLB parameter attached to the
prefetcher, but making it explicit makes these more symmetric with the
Ruby prefetcher, and reduces the complexity of the TLB implementation.
Change-Id: I6921943c49af19971b84225ecfd1127304363426
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/50352
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
As prefetcher can use VA and need translation, it is
interesting to see both VA and PA when printing the queues.
PA is printed as 0 if translation has not happened yet.
Also fix a bug when the pkt is not yet created.
Change-Id: I7cd225379c2930a8d6a7882efdb3dc7bc49fb8a3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48683
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Daniel Carvalho <odanrc@yahoo.com.br>
Now that we're using c++17, the type_traits with a ::value member have
a _v alias which reduces verbosity. Or on other words
std::is_integral<T>::value
can be replaced with
std::is_integral_v<T>
Make this substitution throughout the code base. In places where gem5
introduced it's own similar templates, add a V alias, spelled
differently to match gem5's internal style.
gem5: :IsVarArgs<T>::value => gem5::IsVarArgsV<T>
Change-Id: I1d84ffc4a236ad699471569e7916ec17fe5f109a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48604
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Add an accuracy and coverage stat for the prefetchers.
Accuracy is defined as the ratio of the number of prefetch
request that have been counted as useful over the number
of prefetch request issued.
Accuracy tells whether the prefetcher is producing useful
requests or not.
Coverage is defined as the ratio of of the number of prefetch
request that have been counted as useful over the number of
demand misses if there was no prefetch, which is counted as
the number of useful prefetch request plus the remaining
demand misses. Due to the way stats are defined in the cache,
I have to add a stat to count the number of remaining demand
misses directly in the prefetcher stat. Demand is defined
as being one of this request type: ReadReq, WriteReq,
WriteLineReq, ReadExReq, ReadCleanReq, ReadSharedReq.
Coverage tells what part of misses are covered by the prefetcher.
Change-Id: I3bb8838f87b42665fdd782889f6ba56ca2a802fc
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47603
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Daniel Carvalho <odanrc@yahoo.com.br>
Tested-by: kokoro <noreply+kokoro@google.com>
Count how many time a prefetch is useful, meaning
a hit has happened on a prefetched cache block.
Another stat (pfUsefulButMiss) has been added to count
the special case where there is a hit on prefetched block
but it is counted as a miss because the block is not in
the requested coherency state.
Change-Id: I253216b9ac96d5f21139b710c489d6eb3fce7136
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47602
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Daniel Carvalho <odanrc@yahoo.com.br>
Tested-by: kokoro <noreply+kokoro@google.com>
Apply the gem5 namespace to the codebase.
Some anonymous namespaces could theoretically be removed,
but since this change's main goal was to keep conflicts
at a minimum, it was decided not to modify much the
general shape of the files.
A few missing comments of the form "// namespace X" that
occurred before the newly added "} // namespace gem5"
have been added for consistency.
std out should not be included in the gem5 namespace, so
they weren't.
ProtoMessage has not been included in the gem5 namespace,
since I'm not familiar with how proto works.
Regarding the SystemC files, although they belong to gem5,
they actually perform integration between gem5 and SystemC;
therefore, it deserved its own separate namespace.
Files that are automatically generated have been included
in the gem5 namespace.
The .isa files currently are limited to a single namespace.
This limitation should be later removed to make it easier
to accomodate a better API.
Regarding the files in util, gem5:: was prepended where
suitable. Notice that this patch was tested as much as
possible given that most of these were already not
previously compiling.
Change-Id: Ia53d404ec79c46edaa98f654e23bc3b0e179fe2d
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46323
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The AMPM paper (https://www.jilp.org/vol13/v13paper3.pdf) defines
the bandwidth-delay calculation as :
Mbandwidth= (Nrequests/Tepoch)×Tlatency
In the code, Tepoch and Tlatency are in ticks (which is okay),
but Tepoch is converted from Cycles (256K) to Ticks using the
clockEdge(Cycle c) function, which is incorrect as it yields currentTick
+ c * clockPeriod() instead of just c * clockPeriod().
In other words, the divider keeps increasing as time advances.
This patch substitutes clockEdge() with cyclesToTicks() to keep
the epoch length (Tepoch) constant throughout simulation.
Change-Id: I69dee29892fa4b9eb8de8715fd72a535e122687f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46479
Reviewed-by: Nathanael Premillieu <nathanael.premillieu@huawei.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
According to the DPC paper : "If the best score is less
than or equal to a fixed value BADSCORE, we turn prefetchoff
during the next phase"
However, the current code will turn prefetch off if the best
*offset* of the learning phase is less than BADSCORE, which
is incorrect.
Change-Id: Ib5790fe1341f2dd6328ec3b018bc52012e376723
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/46259
Reviewed-by: Nathanael Premillieu <nathanael.premillieu@huawei.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
As part of recent decisions regarding namespace
naming conventions, all namespaces will be changed
to snake case.
::Stats became ::statistics.
"statistics" was chosen over "stats" to avoid generating
conflicts with the already existing variables (there are
way too many "stats" in the codebase), which would make
this patch even more disturbing for the users.
Change-Id: If877b12d7dac356f86e3b3d941bf7558a4fd8719
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45421
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
As part of recent decisions regarding namespace
naming conventions, all namespaces will be changed
to snake case.
::Prefetcher became ::prefetcher.
"prefetch" was chosen over "prefetcher" to avoid generating
conflicts with the already existing variables. "prefetcher"
is a name that is expected to be more common in user's code
than "prefetch".
Change-Id: I8f07217f278a0229e05545b7847f2620ed208c66
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/45410
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
The systemc dir was not included in this fix.
First it was identified that there were only occurrences
at 0, 1, and 2 levels of indentation (and 2 of 2 spaces,
1 of 3 spaces and 2 of 12 spaces), using:
grep -nrE --exclude-dir=systemc \
"^ *enum [A-Za-z].* {$" src/
Then the following commands were run to replace:
<indent level>enum X ... {
by:
<indent level>enum X ...
<indent level>{
Level 0:
grep -nrl --exclude-dir=systemc \
"^enum [A-Za-z].* {$" src/ | \
xargs sed -Ei \
's/^enum ([A-Za-z].*) \{$/enum \1\n\{/g'
Level 1:
grep -nrl --exclude-dir=systemc \
"^ enum [A-Za-z].* {$" src/ | \
xargs sed -Ei \
's/^ enum ([A-Za-z].*) \{$/ enum \1\n \{/g'
and so on.
Change-Id: Ib186cf379049098ceaec20dfe4d1edcedd5f940d
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/43326
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The systemc dir was not included in this fix.
First it was identified that there were only occurrences
at 0, 1, 2 and 3 levels of indentation (and a single
occurrence of 2 and 3 spaces), using:
grep -nrE --exclude-dir=systemc \
"^ *struct [A-Za-z].* {$" src/
Then the following commands were run to replace:
<indent level>struct X ... {
by:
<indent level>struct X ...
<indent level>{
Level 0:
grep -nrl --exclude-dir=systemc
"^struct [A-Za-z].* {$" src/ | \
xargs sed -Ei \
's/^struct ([A-Za-z].*) \{$/struct \1\n\{/g'
Level 1:
grep -nrl --exclude-dir=systemc \
"^ struct [A-Za-z].* {$" src/ | \
xargs sed -Ei \
's/^ struct ([A-Za-z].*) \{$/ struct \1\n \{/g'
and so on.
Change-Id: I362ef58c86912dabdd272c7debb8d25d587cd455
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39017
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
The systemc dir was not included in this fix.
First it was identified that there were only occurrences
at 0, 1, and 2 levels of indentation, using:
grep -nrE --exclude-dir=systemc \
"^ *class [A-Za-z].* {$" src/
Then the following commands were run to replace:
<indent level>class X ... {
by:
<indent level>class X ...
<indent level>{
Level 0:
grep -nrl --exclude-dir=systemc
"^class [A-Za-z].* {$" src/ | \
xargs sed -Ei \
's/^class ([A-Za-z].*) \{$/class \1\n\{/g'
Level 1:
grep -nrl --exclude-dir=systemc \
"^ class [A-Za-z].* {$" src/ | \
xargs sed -Ei \
's/^ class ([A-Za-z].*) \{$/ class \1\n \{/g'
and so on.
Change-Id: I17615ce16a333d69867b27c7bae0f4fdafd8b2eb
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/39015
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
