This patch add a new Ruby cache coherence protocol based on Arm' AMBA5
CHI specification. The CHI protocol defines and implements two state
machine types:
- Cache_Controller: generic cache controller that can be configured as:
- Top-level L1 I/D cache
- A intermediate level (L2, L3, ...) private or shared cache
- A CHI home node (i.e. the point of coherence of the system and
has the global directory)
- A DMA requester
- Memory_Controller: implements a CHI slave node and interfaces with
gem5 memory controller. This controller has the functionality of a
Directory_Controller on the other Ruby protocols, except it doesn't
have a directory.
The Cache_Controller has multiple cache allocation/deallocation
parameters to control the clusivity with respect to upstream caches.
Allocation can be completely disabled to use Cache_Controller as a
DMA requester or as a home node without a shared LLC.
The standard configuration file configs/ruby/CHI.py provides a
'create_system' compatible with configs/example/fs.py and
configs/example/se.py and creates a system with private L1/L2 caches
per core and a shared LLC at the home nodes. Different cache topologies
can be defined by modifying 'create_system' or by creating custom
scripts using the structures defined in configs/ruby/CHI.py.
This patch also includes the 'CustomMesh' topology script to be used
with CHI. CustomMesh generates a 2D mesh topology with the placement
of components manually defined in a separate configuration file using
the --noc-config parameter.
The example in configs/example/noc_config/2x4.yaml creates a simple 2x4
mesh. For example, to run a SE mode simulation, with 4 cores,
4 mem ctnrls, and 4 home nodes (L3 caches):
build/ARM/gem5.opt configs/example/se.py \
--cmd 'tests/test-progs/hello/bin/arm/linux/hello' \
--ruby --num-cpus=4 --num-dirs=4 --num-l3caches=4 \
--topology=CustomMesh --noc-config=configs/example/noc_config/2x4.yaml
If one doesn't care about the component placement on the interconnect,
the 'Crossbar' and 'Pt2Pt' may be used and they do not require the
--noc-config option.
Additional authors:
Joshua Randall <joshua.randall@arm.com>
Pedro Benedicte <pedro.benedicteillescas@arm.com>
Tuan Ta <tuan.ta2@arm.com>
JIRA: https://gem5.atlassian.net/browse/GEM5-908
Change-Id: I856524b0afd30842194190f5bd69e7e6ded906b0
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42563
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
