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37 * Authors: Vasileios Spiliopoulos
39 * Stephan Diestelhorst
44 * DVFSHandler and DomainConfig class declaration used for managing voltage
45 * and frequency scaling of the various DVFS domains in the system (with each
46 * domain having their independent domain configuration information)
50 #ifndef __SIM_DVFS_HANDLER_HH__
51 #define __SIM_DVFS_HANDLER_HH__
55 #include "debug/DVFS.hh"
56 #include "params/ClockDomain.hh"
57 #include "params/DVFSHandler.hh"
58 #include "params/VoltageDomain.hh"
59 #include "sim/clock_domain.hh"
60 #include "sim/eventq.hh"
61 #include "sim/sim_object.hh"
62 #include "sim/voltage_domain.hh"
65 * DVFS Handler class, maintains a list of all the domains it can handle.
66 * Each entry of that list is an object of the DomainConfig class, and the
67 * handler uses the methods provided by that class to get access to the
68 * configuration of each domain. The handler is responsible for setting/getting
69 * clock periods and voltages from clock/voltage domains.
70 * The handler acts the bridge between software configurable information
71 * for each domain as provided to the controller and the hardware
72 * implementation details for those domains.
74 class DVFSHandler : public SimObject
77 typedef DVFSHandlerParams Params;
78 DVFSHandler(const Params *p);
80 typedef SrcClockDomain::DomainID DomainID;
81 typedef SrcClockDomain::PerfLevel PerfLevel;
84 * Get the number of domains assigned to this DVFS handler.
85 * @return Number of domains
87 uint32_t numDomains() const { return domainIDList.size(); }
90 * Get the n-th domain ID, from the domains managed by this handler.
93 DomainID domainID(uint32_t index) const;
96 * Check whether a domain ID is known to the handler or not.
97 * @param domain_id Domain ID to check
98 * @return Domain ID known to handler?
100 bool validDomainID(DomainID domain_id) const;
103 * Get transition latency to switch between performance levels.
104 * @return Transition latency
106 Tick transLatency() const { return _transLatency; }
109 * Set a new performance level for the specified domain. The actual update
110 * will be delayed by transLatency().
112 * @param domain_id Software visible ID of the domain to be configured
113 * @param perf_level Requested performance level (0 - fast, >0 slower)
114 * @return status whether the setting was successful
116 bool perfLevel(DomainID domain_id, PerfLevel perf_level);
119 * Get the current performance level of a domain. While a change request is
120 * in-flight, will return the current (i.e. old, unmodified) value.
122 * @param domain_id Domain ID to query
123 * @return Current performance level of the specified domain
125 PerfLevel perfLevel(DomainID domain_id) const {
127 return findDomain(domain_id)->perfLevel();
131 * Read the clock period of the specified domain at the specified
133 * @param domain_id Domain ID to query
134 * @param perf_level Performance level of interest
135 * @return Clock period in ticks for the requested performance level of
136 * the respective domain
138 Tick clkPeriodAtPerfLevel(DomainID domain_id, PerfLevel perf_level) const
140 SrcClockDomain *d = findDomain(domain_id);
142 PerfLevel n = d->numPerfLevels();
144 return d->clkPeriodAtPerfLevel(perf_level);
146 warn("DVFSHandler %s reads illegal frequency level %u from "\
147 "SrcClockDomain %s. Returning 0\n", name(), perf_level, d->name());
152 * Read the voltage of the specified domain at the specified
154 * @param domain_id Domain ID to query
155 * @param perf_level Performance level of interest
156 * @return Voltage for the requested performance level of the respective
159 double voltageAtPerfLevel(DomainID domain_id, PerfLevel perf_level) const
161 VoltageDomain *d = findDomain(domain_id)->voltageDomain();
163 PerfLevel n = d->numVoltages();
165 return d->voltage(perf_level);
167 // Request outside of the range of the voltage domain
169 DPRINTF(DVFS, "DVFS: Request for perf-level %i for single-point "\
170 "voltage domain %s. Returning voltage at level 0: %.2f "\
171 "V\n", perf_level, d->name(), d->voltage(0));
172 // Special case for single point voltage domain -> same voltage for
174 return d->voltage(0);
177 warn("DVFSHandler %s reads illegal voltage level %u from "\
178 "VoltageDomain %s. Returning 0 V\n", name(), perf_level, d->name());
183 * Get the total number of available performance levels.
185 * @param domain_id Domain ID to query
186 * @return Number of performance levels that where configured for the
189 PerfLevel numPerfLevels(PerfLevel domain_id) const
191 return findDomain(domain_id)->numPerfLevels();
195 * Check enable status of the DVFS handler, when the handler is disabled, no
196 * request should be sent to the handler.
197 * @return True, if the handler is enabled
199 bool isEnabled() const { return enableHandler; }
201 void serialize(CheckpointOut &cp) const M5_ATTR_OVERRIDE;
202 void unserialize(CheckpointIn &cp) M5_ATTR_OVERRIDE;
205 typedef std::map<DomainID, SrcClockDomain*> Domains;
209 * List of IDs avaiable in the domain list
211 std::vector<DomainID> domainIDList;
214 * Clock domain of the system the handler is instantiated.
216 SrcClockDomain* sysClkDomain;
219 * Search for a domain based on the domain ID.
221 * @param domain_id Domain ID to search for
222 * @return Pointer to the source clock domain with matching ID.
224 SrcClockDomain *findDomain(DomainID domain_id) const {
225 auto it = domains.find(domain_id);
226 panic_if(it == domains.end(),
227 "DVFS: Could not find a domain for ID %d.\n",domain_id );
228 return domains.find(domain_id)->second;
232 * Disabling the DVFS handler ensures that all the DVFS migration requests
233 * are ignored. Domains remain at their default frequency and voltage.
239 * This corresponds to the maximum transition latency associated with the
240 * hardware transitioning from a particular performance level to the other
242 const Tick _transLatency;
247 * Update performance level event, encapsulates all the required information
248 * for a future call to change a domain's performance level.
250 struct UpdateEvent : public Event {
251 UpdateEvent() : Event(DVFS_Update_Pri), domainIDToSet(0),
255 * Static pointer to the single DVFS hander for all the update events
257 static DVFSHandler *dvfsHandler;
260 * ID of the domain that will be changed by the in-flight event
262 DomainID domainIDToSet;
265 * Target performance level of the in-flight event
267 PerfLevel perfLevelToSet;
270 * Updates the performance level by modifying the clock and the voltage
271 * of the associated clocked objects. Gets information from
272 * domainIDToSet and perfLevelToSet for easier calling through an
275 void updatePerfLevel();
277 void process() { updatePerfLevel(); }
280 typedef std::map<DomainID, UpdateEvent> UpdatePerfLevelEvents;
282 * Map from domain IDs -> perf level update events, records in-flight change
283 * requests per domain ID.
285 UpdatePerfLevelEvents updatePerfLevelEvents;
288 #endif // __SIM_DVFS_HANDLER_HH__