1 /* Copyright (c) 2010-2018. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "simgrid/plugins/dvfs.h"
7 #include "simgrid/plugins/load.h"
8 #include "src/plugins/vm/VirtualMachineImpl.hpp"
9 #include <xbt/config.hpp>
11 #include <boost/algorithm/string.hpp>
13 SIMGRID_REGISTER_PLUGIN(host_dvfs, "Dvfs support", &sg_host_dvfs_plugin_init)
15 static simgrid::config::Flag<double> cfg_sampling_rate("plugin/dvfs/sampling-rate", {"plugin/dvfs/sampling_rate"},
16 "How often should the dvfs plugin check whether the frequency needs to be changed?", 0.1,
17 [](double val){if (val != 0.1) sg_host_dvfs_plugin_init();});
19 static simgrid::config::Flag<std::string> cfg_governor("plugin/dvfs/governor",
20 "Which Governor should be used that adapts the CPU frequency?", "performance",
22 std::map<std::string, std::string>({
23 {"conservative", "TODO: Doc"},
24 {"ondemand", "TODO: Doc"},
25 {"performance", "TODO: Doc"},
26 {"powersave", "TODO: Doc"},
29 [](std::string val){if (val != "performance") sg_host_dvfs_plugin_init();});
31 /** @addtogroup SURF_plugin_load
33 This plugin makes it very simple for users to obtain the current load for each host.
37 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_plugin_dvfs, surf, "Logging specific to the SURF HostDvfs plugin");
46 simgrid::s4u::Host* const host_;
47 double sampling_rate_;
50 simgrid::s4u::Host* get_host() const { return host_; }
54 explicit Governor(simgrid::s4u::Host* ptr) : host_(ptr) { init(); }
55 virtual ~Governor() = default;
56 virtual std::string get_name() = 0;
60 const char* local_sampling_rate_config = host_->get_property(cfg_sampling_rate.get_name());
61 double global_sampling_rate_config = cfg_sampling_rate;
62 if (local_sampling_rate_config != nullptr) {
63 sampling_rate_ = std::stod(local_sampling_rate_config);
65 sampling_rate_ = global_sampling_rate_config;
69 virtual void update() = 0;
70 double get_sampling_rate() { return sampling_rate_; }
74 * The linux kernel doc describes this governor as follows:
75 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
77 * > The CPUfreq governor "performance" sets the CPU statically to the
78 * > highest frequency within the borders of scaling_min_freq and
81 * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency.
83 class Performance : public Governor {
85 explicit Performance(simgrid::s4u::Host* ptr) : Governor(ptr) {}
86 std::string get_name() override { return "Performance"; }
88 void update() override { get_host()->set_pstate(0); }
92 * The linux kernel doc describes this governor as follows:
93 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
95 * > The CPUfreq governor "powersave" sets the CPU statically to the
96 * > lowest frequency within the borders of scaling_min_freq and
99 * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency.
101 class Powersave : public Governor {
103 explicit Powersave(simgrid::s4u::Host* ptr) : Governor(ptr) {}
104 std::string get_name() override { return "Powersave"; }
106 void update() override { get_host()->set_pstate(get_host()->get_pstate_count() - 1); }
110 * The linux kernel doc describes this governor as follows:
111 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
113 * > The CPUfreq governor "ondemand" sets the CPU frequency depending on the
114 * > current system load. [...] when triggered, cpufreq checks
115 * > the CPU-usage statistics over the last period and the governor sets the
118 class OnDemand : public Governor {
120 * See https://elixir.bootlin.com/linux/v4.15.4/source/drivers/cpufreq/cpufreq_ondemand.c
121 * DEF_FREQUENCY_UP_THRESHOLD and od_update()
123 double freq_up_threshold_ = 0.80;
126 explicit OnDemand(simgrid::s4u::Host* ptr) : Governor(ptr) {}
127 std::string get_name() override { return "OnDemand"; }
129 void update() override
131 double load = get_host()->get_core_count() * sg_host_get_avg_load(get_host());
132 sg_host_load_reset(get_host()); // Only consider the period between two calls to this method!
134 if (load > freq_up_threshold_) {
135 get_host()->set_pstate(0); /* Run at max. performance! */
136 XBT_INFO("Load: %f > threshold: %f --> changed to pstate %i", load, freq_up_threshold_, 0);
138 /* The actual implementation uses a formula here: (See Kernel file cpufreq_ondemand.c:158)
140 * freq_next = min_f + load * (max_f - min_f) / 100
142 * So they assume that frequency increases by 100 MHz. We will just use
143 * lowest_pstate - load*pstatesCount()
145 int max_pstate = get_host()->get_pstate_count() - 1;
146 // Load is now < freq_up_threshold; exclude pstate 0 (the fastest)
147 // because pstate 0 can only be selected if load > freq_up_threshold_
148 int new_pstate = max_pstate - load * (max_pstate + 1);
149 get_host()->set_pstate(new_pstate);
151 XBT_DEBUG("Load: %f < threshold: %f --> changed to pstate %i", load, freq_up_threshold_, new_pstate);
157 * This is the conservative governor, which is very similar to the
158 * OnDemand governor. The Linux Kernel Documentation describes it
159 * very well, see https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt:
161 * > The CPUfreq governor "conservative", much like the "ondemand"
162 * > governor, sets the CPU frequency depending on the current usage. It
163 * > differs in behaviour in that it gracefully increases and decreases the
164 * > CPU speed rather than jumping to max speed the moment there is any load
165 * > on the CPU. This behaviour is more suitable in a battery powered
168 class Conservative : public Governor {
169 double freq_up_threshold_ = .8;
170 double freq_down_threshold_ = .2;
173 explicit Conservative(simgrid::s4u::Host* ptr) : Governor(ptr) {}
174 virtual std::string get_name() override { return "Conservative"; }
176 virtual void update() override
178 double load = get_host()->get_core_count() * sg_host_get_avg_load(get_host());
179 int pstate = get_host()->get_pstate();
180 sg_host_load_reset(get_host()); // Only consider the period between two calls to this method!
182 if (load > freq_up_threshold_) {
184 get_host()->set_pstate(pstate - 1);
185 XBT_INFO("Load: %f > threshold: %f -> increasing performance to pstate %d", load, freq_up_threshold_,
188 XBT_DEBUG("Load: %f > threshold: %f -> but cannot speed up even more, already in highest pstate %d", load,
189 freq_up_threshold_, pstate);
191 } else if (load < freq_down_threshold_) {
192 int max_pstate = get_host()->get_pstate_count() - 1;
193 if (pstate != max_pstate) { // Are we in the slowest pstate already?
194 get_host()->set_pstate(pstate + 1);
195 XBT_INFO("Load: %f < threshold: %f -> slowing down to pstate %d", load, freq_down_threshold_, pstate + 1);
197 XBT_DEBUG("Load: %f < threshold: %f -> cannot slow down even more, already in slowest pstate %d", load,
198 freq_down_threshold_, pstate);
205 * Add this to your host tag:
206 * - \<prop id="plugin/dvfs/governor" value="performance" /\>
208 * Valid values as of now are: performance, powersave, ondemand, conservative
209 * It doesn't matter if you use uppercase or lowercase.
211 * For the sampling rate, use this:
213 * - \<prop id="plugin/dvfs/sampling-rate" value="2" /\>
215 * This will run the update() method of the specified governor every 2 seconds
218 * These properties can also be used within the \<config\> tag to configure
219 * these values globally. Using them within the \<host\> will overwrite this
220 * global configuration
223 } // namespace plugin
224 } // namespace simgrid
226 /* **************************** events callback *************************** */
227 static void on_host_added(simgrid::s4u::Host& host)
229 if (dynamic_cast<simgrid::s4u::VirtualMachine*>(&host)) // Ignore virtual machines
232 std::string name = std::string("dvfs-daemon-") + host.get_cname();
233 simgrid::s4u::ActorPtr daemon = simgrid::s4u::Actor::create(name.c_str(), &host, []() {
235 * This lambda function is the function the actor (daemon) will execute
236 * all the time - in the case of the dvfs plugin, this controls when to
237 * lower/raise the frequency.
239 simgrid::s4u::ActorPtr daemon_proc = simgrid::s4u::Actor::self();
241 XBT_DEBUG("DVFS process on %s is a daemon: %d", daemon_proc->get_host()->get_cname(), daemon_proc->is_daemon());
243 std::string dvfs_governor;
244 const char* host_conf = daemon_proc->get_host()->get_property("plugin/dvfs/governor");
245 if (host_conf != nullptr) {
246 dvfs_governor = std::string(host_conf);
247 boost::algorithm::to_lower(dvfs_governor);
249 dvfs_governor = cfg_governor;
250 boost::algorithm::to_lower(dvfs_governor);
253 auto governor = [&dvfs_governor, &daemon_proc]() {
254 if (dvfs_governor == "conservative") {
255 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
256 new simgrid::plugin::dvfs::Conservative(daemon_proc->get_host()));
257 } else if (dvfs_governor == "ondemand") {
258 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
259 new simgrid::plugin::dvfs::OnDemand(daemon_proc->get_host()));
260 } else if (dvfs_governor == "performance") {
261 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
262 new simgrid::plugin::dvfs::Performance(daemon_proc->get_host()));
263 } else if (dvfs_governor == "powersave") {
264 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
265 new simgrid::plugin::dvfs::Powersave(daemon_proc->get_host()));
267 XBT_CRITICAL("No governor specified for host %s, falling back to Performance",
268 daemon_proc->get_host()->get_cname());
269 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
270 new simgrid::plugin::dvfs::Performance(daemon_proc->get_host()));
275 // Sleep *before* updating; important for startup (i.e., t = 0).
276 // In the beginning, we want to go with the pstates specified in the platform file
277 // (so we sleep first)
278 simgrid::s4u::this_actor::sleep_for(governor->get_sampling_rate());
280 XBT_DEBUG("Governor (%s) just updated!", governor->get_name().c_str());
283 XBT_WARN("I should have never reached this point: daemons should be killed when all regular processes are done");
287 // This call must be placed in this function. Otherwise, the daemonize() call comes too late and
288 // SMPI will take this process as an MPI process!
292 /* **************************** Public interface *************************** */
294 /** @ingroup SURF_plugin_load
295 * @brief Initializes the HostDvfs plugin
296 * @details The HostDvfs plugin provides an API to get the current load of each host.
298 void sg_host_dvfs_plugin_init()
300 static bool inited = false;
305 sg_host_load_plugin_init();
307 simgrid::s4u::Host::on_creation.connect(&on_host_added);