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PowerDomains group multiple objects together to regulate their power state. There are 2 types of objects in a PowerDomain: leaders and followers. The power state of a PowerDomain is the most performant power state of any of the leaders. The power state of the followers is determined by the power state of the PowerDomain they belong to: they need to be in a power state which is more or equally performant to the power state of the PowerDomain. Leaders can be ClockedObjects or other PowerDomains. Followers can only be ClockedObjects. PowerDomains can be be nested but a PowerDomain can only be a leader of another PowerDomain, NOT a follower. PowerDomains are not present in the hierarchy by default, the user needs to create and configure them in the configuration file. The user can add an hierachy by setting the led_by parameter. gem5 will then create leaders and followers for each domain and calculate the allowed power states for the domain. Objects in a PowerDomain need to have at least the ON state in the possible_states. An example of a powerDomain config is: pd = PowerDomain() cpu0 = BaseCPU() cpu1 = BaseCPU() shared_cache = BaseCache() cache.power_state.led_by = pd pd.led_by = [cpu0, cpu1] This will create a PowerDomain, where the CPUs determine their own power states and the shared cache (via the PowerDomain) follows those power states (when possible). Change-Id: I4c4cd01f06d45476c6e0fb2afeb778613733e2ff Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com> Reviewed-by: Sascha Bischoff <sascha.bischoff@arm.com> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28051 Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu> Maintainer: Jason Lowe-Power <power.jg@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>
This is the gem5 simulator. The main website can be found at http://www.gem5.org A good starting point is http://www.gem5.org/about, and for more information about building the simulator and getting started please see http://www.gem5.org/documentation and http://www.gem5.org/documentation/learning_gem5/introduction. To build gem5, you will need the following software: g++ or clang, Python (gem5 links in the Python interpreter), SCons, SWIG, zlib, m4, and lastly protobuf if you want trace capture and playback support. Please see http://www.gem5.org/documentation/general_docs/building for more details concerning the minimum versions of the aforementioned tools. Once you have all dependencies resolved, type 'scons build/<ARCH>/gem5.opt' where ARCH is one of ARM, NULL, MIPS, POWER, SPARC, or X86. This will build an optimized version of the gem5 binary (gem5.opt) for the the specified architecture. See http://www.gem5.org/documentation/general_docs/building for more details and options. The basic source release includes these subdirectories: - configs: example simulation configuration scripts - ext: less-common external packages needed to build gem5 - src: source code of the gem5 simulator - system: source for some optional system software for simulated systems - tests: regression tests - util: useful utility programs and files To run full-system simulations, you will need compiled system firmware (console and PALcode for Alpha), kernel binaries and one or more disk images. If you have questions, please send mail to gem5-users@gem5.org Enjoy using gem5 and please share your modifications and extensions.