This PR adds the SMS prefetcher described in [this
](https://web.eecs.umich.edu/~twenisch/papers/isca06.pdf) paper.
This work was done in collaboration with @Setu-Gupta, and @xmlizhao
On branch sms
Changes to be committed:
modified: src/mem/cache/prefetch/Prefetcher.py
modified: src/mem/cache/prefetch/SConscript
new file: src/mem/cache/prefetch/sms.cc
new file: src/mem/cache/prefetch/sms.hh
Change-Id: I68d3bb6cf07385177d0f776fb958f652cfc41489
- This change updates syntax of constructors of Template Classes from
`class<T>()` to `class()`
- Initializes coherence to 0 in `src/mem/cache_blk.hh`
The above changes are made to solve the errors when compiling gem5 in
gcc 14
This will allow gem5 to configure the maximum capacity of a
partition dynamically during simulation, rather than
having it statically defined at construction time
Change-Id: Ib55c9990a6bc2930abaf2438c13337acc643520f
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
In this way we actually need to store one unsigned integer instead of
two. We also won't need to recompute the total number of cache blocks
whenever we will adapt this policy to be dynamically modified
Change-Id: Ia8cf906539d1891b6cdb821f2a74628127dc68c6
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
This commit is adjusting the constructor to relax template
requirements. In this way child classes are free to provide
their own way of calculating the number of entries and the
shifting required to extract the set
Why do we need this?
Up to this patch we have been configuring the indexing policy
by setting up the cache/table size (in bytes) and the entry size.
Those parameters make a lot of sense in caching structures
where:
a) We want to configure the caching structure using
the amount of storage (in bytes) provided (e.g. 4kB of Cache)
b) the content of a single entry is addressable therefore
we need the entry size to know how many bits in the indexing
process we need to shift to extract the set
In those cases the number of cache entries is derived from the formula
num_entries = size / entry_size
The adoption of the IndexingPolicy for different kinds
of caching structures (e.g. prefetcher tables) make this
way of configuring the IP a bit quirky.
For some tables directly setting the number of entries is a far more
intuitive way of configuring the IP, instead of allocating the desired
number of entries by working things out with the formula above
Change-Id: Ic7994c129196d6ba83dc99ce397ad43393d35252
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
We don't store a pointer to the indexing policy anymore.
Instead, we register a tag extractor callback when we
construct the TaggedEntry
Change-Id: I79dbc1bc5c5ce90d350e83451f513c05da9f0d61
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
We don't store a pointer to the indexing policy anymore.
Instead, we register a tag extractor callback when we
construct the CacheEntry
Change-Id: I06dc58e2f67e01f3f9bcd9f0c641505d3aec82ff
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
As detailed by a previous commit, AssociativeSet is not needed anymore.
The class is effectively the same as AssociativeCache
Change-Id: I24bfb98fbf0826c0a2ea6ede585576286f093318
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
The only difference between the TaggedEntry and the newly defined
CacheEntry is the presence of the secure flag in the first case. The
need to tag a cache entry according to the security bit required the
overloading of the matching methods in the TaggedEntry class to take
security into account (See matchTag [1]), and the persistance after
PR #745 of the AssociativeSet class which is basically identical
to its AssociativeCache superclass, only it overrides its virtual
method to match the tag according to the secure bit as well.
The introduction of the KeyType parameter in the previous commit
will smoothe the differences and help unifying the interface.
Rather than overloading and overriding to account for a different
signature, we embody the difference in the KeyType class. A
CacheEntry will match with KeyType = Addr,
whereas a TaggedEntry will use the following lookup type proposed in this
patch:
struct KeyType {
Addr address;
bool secure;
}
This patch is partly reverting the changes in #745 which were
reimplementing TaggedEntry on top of the CacheEntry. Instead
we keep them separate as the plan is to allow different
entry types with templatization rather than polymorphism.
As a final note, I believe a separate commit will have to
change the naming of our entries; the CacheEntry should
probably be renamed into TaggedEntry and the current TaggedEntry
into something that reflect the presence of the security bit
alongside the traditional address tag
[1]: https://github.com/gem5/gem5/blob/stable/\
src/mem/cache/tags/tagged_entry.hh#L81
Change-Id: Ifc104c8d0c1d64509f612d87b80d442e0764f7ca
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
The KeyType data type is the type of the lookup and the cache extracts
it from the Entry template parameter
Change-Id: I147d7c2503abc11becfeebe6336e7f90989ad4e8
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Exposing the tag of a cache entry through the associative
cache APIs makes it hard to generalize the cache for
structured tags. Ultimately the tag should be a property
of the cache entry and any tag extraction logic (if needed)
should reside there. In this we can reuse the associative
cache for different Entry params, each one bearing a different
representation of a tag
Change-Id: I51b4526be64683614e01d763b1656e5be23a611b
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Some compilers (gcc version 12.3.0) will start complaining when perfect
forwarding the StrideEntry argument constructed with an extra parameter
(see later patches).
Using a pointer seems to fix the gcc bug.
The commit is also changing the signature of findTable and allocateContext
so that a reference rather than a pointer is return. In this way we don't
deal with the hack of returning a raw ptr from a unique_ptr
Change-Id: Idd451208aae80bbfae76110c859e93084bcb2635
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
The code is already assuming a fully associative cache. Rather than
calling getPossibleEntries with a random value and therefore needlessly
passing a vector of pointers, we use the AssociativeCache iterator to
loop over the cache entries
Change-Id: Ic99cbd39ee9f12eef9091d9d62ca24d0c3e61300
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
This PR fixes the issues with the implementation of the Best Offset
Prefetcher described in issue #1402
On branch bop
Changes to be committed:
modified: src/mem/cache/prefetch/bop.cc
modified: src/mem/cache/prefetch/bop.hh
---------
Co-authored-by: Setu Gupta <setu.gupta.2020@gamil.com>
Co-authored-by: Abhishek Shailendra Singh <abs218@leigh.edu>
Co-authored-by: Setu Gupta <setu.gupta@partner.samsung.com>
This PR fixes the issues mentioned in #1448.
**Note that this contribution is the result of a joint collaboration
with @AbhishekUoR**
This PR introduces the following 4 changes:
1. It changes the addresses which are used to compute the stride to
cache line aligned addresses (the current version uses word aligned
addresses)
2. It correctly returns if the stride does not match (as opposed to
issuing prefetches using the new stride incorrectly)
3. It returns if the new stride is 0, indicating multiple reads from the
same cache line.
4. It removes code which is no longer necessary after the addition of
changes number 1 and 3.
Change-Id: Ic346d0e15df6d07e2b93289c8d6b89b4c2f45a34
---------
Co-authored-by: Abhishek Shailendra Singh <abs218@leigh.edu>
This commit removes some comments and adds constexpr in front
of "bool is_secure..." in pif.cc, signature_path.cc, and
signature_path_v2.cc
Change-Id: Icafe1d7c97d1d3fbf6abc12ba87ebb596255b96f
This modifies the crash fix so that the function calls that were
modified use a local variables called `is_secure` instead of a
hardcoded `false`. Some of these existed previously so it made
more sense to use them, while others were newly added in to mark
where the code might need to be changed later.
Change-Id: I0c0d14b74f0ccf70ee5fe7c8b01ed0266353b3c1
This commit fixes the "Need is_secure arg" crash that occurs when
using the IndirectMemoryPrefetcher, SignaturePathPrefetcher,
SignaturePathPrefetcherV2, STeMSPrefetcher, and PIFPrefetcher. This
was done by changing some variables to be AssociativeSet<...>
instead of AssociativeCache<...> and changing the affected function
calls.
Change-Id: I61808c877514efeb73ad041de273ae386711acae
I noticed while using the stable branch that there were a few typos of
the word 'cache' and so I've corrected a few files where I found such
typos.
Change-Id: I7c7f64812039f34fe39d0c45c4f5ce921cba06d0
When compiler tries to inline a vector construction with a default value
as default constructed ReplaceableEntry. It can complain about the
uninitialized member.
Let's provide basic initialization to the members.
Example codepath:
SignaturePathV2 constructor
-> GlobalHistoryEntry() as init_value to AssociativeSet
-> AssociativeSet initialize vector<Entry> with init_value
Remove the requirement in TreePLRU's implementation that the number of
leaves (i.e., the number of cache ways) be a power of two. Firstly, on
some recent processors, this is not the case---for example, Intel Golden
Cove's L1D has 12 ways. Secondly, The implementation of TreePLRU appears
to work just fine as-is with a way count that's not a power of two.
Change-Id: If2a27dc5bbe7a8e96684f79ce791df5c0b582230
AssociativeSet can reuse most of the generic cache library code with the
addition of a secure bit. This reduces duplicated code.
Change-Id: I008ef79b0dd5f95418a3fb79396aeb0a6c601784
The tagged entry can be derived from the generic cache entry and add the secure
flag that it needs. This reduces code duplication.
Change-Id: I7ff0bddc40604a8a789036a6300eabda40339a0f
The DCPT table is better built using the generic cache library since we do not
need the secure bit.
Change-Id: I8a4a8d3dab7fbc3bbc816107492978ac7f3f5934
The frequency table is better built using the generic cache library instead of the
AssociativeSet since the secure bit is not needed for this structure.
Change-Id: Ie3b6442235daec7b350c608ad1380bed58f5ccf4
The new ISA-agnostic interface is the PartitionManager.
We therefore make the PartitionFieldExtention private to the
Arm implementation of memory partitioning (FEAT_MPAM)
Any other partitioning implementation should override the
PartitionManager::readPacketPartitionID to provide a mean
for extracting partitioning data (partition_id) from the
incoming Packet.
With this commit we also define an MPAM MSC which is
supposed to be the partitioning manager for the
Memory System Component
Change-Id: I6959ace0c0cbca549dcc1aacd53dff223b5fe328
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
This is a first step towards offloading some of the partitioning
logic to the partitioning manager. We start with this patch
by replacing the static readPacketPartitionId into a virtual
method owned by the manager.
The issue with readPacketPartitionId as of now is that it relies
on the fixed PartitionFieldExtention.
We want user to be able to extract the partitionId more flexibly
and this requires using a SimObject
Change-Id: I3bd2e81e2a97c55fc83548956fc59f422c8049a6
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
* Add Cache partitioning policies to manage and enforce cache
partitioning:
* Add Way partition policy
* Add MaxCapacity partition policy
* Add PartitionFieldsExtension Extension class for Packets to store
Partition IDs for cache partitioning and monitoring
* Modify Cache SimObjects to store partition policies
* Modify Cache block eviction logic to use new partitioning policies
Co-authored-by: Adrian Herrera <adrian.herrera@arm.com>
Change-Id: Ib35153a8b46803c22a433926270d82e5e19ce544
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
* Add Cache partitioning policies to manage and enforce cache partitioning:
* Add Way partition policy
* Add MaxCapacity partition policy
* Add PartitionFieldsExtension Extension class for Packets to store
Partition IDs for cache partitioning and monitoring
* Modify Cache Tags SimObjects to store partition policies
* Modify Cache Tags block eviction logic to use new partitioning policies
* Add example system and TrafficGen configurations for testing Cache
Partitioning Policies
Change-Id: Ic3fb0f35cf060783fbb9289380721a07e18fad49
Co-authored-by: Adrian Herrera <adrian.herrera@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@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: I3ec0c642bc9ec7635b0d38308797e99b645304bb
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@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: I4ce79c72d74445b12acf68e0a54e13966e30041c
Co-authored-by: Richard Cooper <richard.cooper@arm.com>
Signed-off-by: Richard Cooper <richard.cooper@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
pkt->req->isCacheMaintenance() would not include a check
for clean eviction before notifying the prefetcher,
causing gem5 to crash.
Change-Id: I4a56c7384818c63d6e2263f26645e87cef1243cb
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Update the default prefetch options to achieve out-of-the box
prefetcher performance closer to that which a typical user would
expect. Configurations that set these parameters explicitly will be
unaffected.
The new defaults were identified as part of work on gem5 prefetchers
undertaken by Nikolaos Kyparissas while on internship at Arm.
Change-Id: Ia6c1803c86e42feef01de40c34d928de50fe0bed
Reviewed-by: Andreas Sandberg <andreas.sandberg@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: I3a80a1e3d752f925595e33edebf5359d2cc67182
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
When processing memory Packets for prefetch, the `PrefetchInfo` class
constructor will attempt to copy the `Packet` data. In cases where the
`Packet` under consideration does not contain data, an assertion will be
triggered in the Packet's `getConstPtr` method, causing the simulation
to crash.
This problem was first exposed by Bug #580 when processing an
`UpgradeReq` memory packet.
This patch addresses the problem by suppressing the copying of the
`Packet` data during construction of a `PrefetchInfo` object in cases
where the `Packet` has no data.
This patch addresses Bug #580 [1], which was exposed by PR #564 [2],
subsequently reverted by PR #581 [3]
[1] https://github.com/gem5/gem5/issues/580
[2] https://github.com/gem5/gem5/pull/564
[3] https://github.com/gem5/gem5/pull/581
Change-Id: Ic1e828c0887f4003441b61647440c8e912bf0fbc
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
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>
