gem5 - gem5

Age	Commit message (Collapse)	Author
2014-06-30	power: Add basic DVFS support for gem5	Stephan Diestelhorst
	Adds DVFS capabilities to gem5, by allowing users to specify lists for frequencies and voltages in SrcClockDomains and VoltageDomains respectively. A separate component, DVFSHandler, provides a small interface to change operating points of the associated domains. Clock domains will be linked to voltage domains and thus allow separate clock, but shared voltage lines. Currently all the valid performance-level updates are performed with a fixed transition latency as specified for the domain. Config file example: ... vd = VoltageDomain(voltage = ['1V','0.95V','0.90V','0.85V']) tsys.cluster1.clk_domain.clock = ['1GHz','700MHz','400MHz','230MHz'] tsys.cluster2.clk_domain.clock = ['1GHz','700MHz','400MHz','230MHz'] tsys.cluster1.clk_domain.domain_id = 0 tsys.cluster2.clk_domain.domain_id = 1 tsys.cluster1.clk_domain.voltage_domain = vd tsys.cluster2.clk_domain.voltage_domain = vd tsys.dvfs_handler.domains = [tsys.cluster1.clk_domain, tsys.cluster2.clk_domain] tsys.dvfs_handler.enable = True
2013-08-19	power: Add voltage domains to the clock domains	Akash Bagdia
	This patch adds the notion of voltage domains, and groups clock domains that operate under the same voltage (i.e. power supply) into domains. Each clock domain is required to be associated with a voltage domain, and the latter requires the voltage to be explicitly set. A voltage domain is an independently controllable voltage supply being provided to section of the design. Thus, if you wish to perform dynamic voltage scaling on a CPU, its clock domain should be associated with a separate voltage domain. The current implementation of the voltage domain does not take into consideration cases where there are derived voltage domains running at ratio of native voltage domains, as with the case where there can be on-chip buck/boost (charge pumps) voltage regulation logic. The regression and configuration scripts are updated with a generic voltage domain for the system, and one for the CPUs.
2013-06-27	sim: Add the notion of clock domains to all ClockedObjects	Akash Bagdia
	This patch adds the notion of source- and derived-clock domains to the ClockedObjects. As such, all clock information is moved to the clock domain, and the ClockedObjects are grouped into domains. The clock domains are either source domains, with a specific clock period, or derived domains that have a parent domain and a divider (potentially chained). For piece of logic that runs at a derived clock (a ratio of the clock its parent is running at) the necessary derived clock domain is created from its corresponding parent clock domain. For now, the derived clock domain only supports a divider, thus ensuring a lower speed compared to its parent. Multiplier functionality implies a PLL logic that has not been modelled yet (create a separate clock instead). The clock domains should be used as a mechanism to provide a controllable clock source that affects clock for every clocked object lying beneath it. The clock of the domain can (in a future patch) be controlled by a handler responsible for dynamic frequency scaling of the respective clock domains. All the config scripts have been retro-fitted with clock domains. For the System a default SrcClockDomain is created. For CPUs that run at a different speed than the system, there is a seperate clock domain created. This domain incorporates the CPU and the associated caches. As before, Ruby runs under its own clock domain. The clock period of all domains are pre-computed, such that no virtual functions or multiplications are needed when calling clockPeriod. Instead, the clock period is pre-computed when any changes occur. For this to be possible, each clock domain tracks its children.