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 /** @addtogroup SURF_plugin_load
15 This plugin makes it very simple for users to obtain the current load for each host.
19 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_plugin_dvfs, surf, "Logging specific to the SURF HostDvfs plugin");
21 static const char* property_sampling_rate = "plugin/dvfs/sampling_rate";
22 static const char* property_governor = "plugin/dvfs/governor";
31 simgrid::s4u::Host* const host_;
32 double sampling_rate_;
35 simgrid::s4u::Host* get_host() const { return host_; }
39 explicit Governor(simgrid::s4u::Host* ptr) : host_(ptr) { init(); }
40 virtual ~Governor() = default;
41 virtual std::string get_name() = 0;
45 const char* local_sampling_rate_config = host_->get_property(property_sampling_rate);
46 double global_sampling_rate_config = simgrid::config::get_value<double>(property_sampling_rate);
47 if (local_sampling_rate_config != nullptr) {
48 sampling_rate_ = std::stod(local_sampling_rate_config);
50 sampling_rate_ = global_sampling_rate_config;
54 virtual void update() = 0;
55 double get_sampling_rate() { return sampling_rate_; }
59 * The linux kernel doc describes this governor as follows:
60 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
62 * > The CPUfreq governor "performance" sets the CPU statically to the
63 * > highest frequency within the borders of scaling_min_freq and
66 * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency.
68 class Performance : public Governor {
70 explicit Performance(simgrid::s4u::Host* ptr) : Governor(ptr) {}
71 std::string get_name() override { return "Performance"; }
73 void update() override { get_host()->set_pstate(0); }
77 * The linux kernel doc describes this governor as follows:
78 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
80 * > The CPUfreq governor "powersave" sets the CPU statically to the
81 * > lowest frequency within the borders of scaling_min_freq and
84 * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency.
86 class Powersave : public Governor {
88 explicit Powersave(simgrid::s4u::Host* ptr) : Governor(ptr) {}
89 std::string get_name() override { return "Powersave"; }
91 void update() override { get_host()->set_pstate(get_host()->get_pstate_count() - 1); }
95 * The linux kernel doc describes this governor as follows:
96 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
98 * > The CPUfreq governor "ondemand" sets the CPU frequency depending on the
99 * > current system load. [...] when triggered, cpufreq checks
100 * > the CPU-usage statistics over the last period and the governor sets the
103 class OnDemand : public Governor {
105 * See https://elixir.bootlin.com/linux/v4.15.4/source/drivers/cpufreq/cpufreq_ondemand.c
106 * DEF_FREQUENCY_UP_THRESHOLD and od_update()
108 double freq_up_threshold_ = 0.80;
111 explicit OnDemand(simgrid::s4u::Host* ptr) : Governor(ptr) {}
112 std::string get_name() override { return "OnDemand"; }
114 void update() override
116 double load = get_host()->get_core_count() * sg_host_get_avg_load(get_host());
117 sg_host_load_reset(get_host()); // Only consider the period between two calls to this method!
119 if (load > freq_up_threshold_) {
120 get_host()->set_pstate(0); /* Run at max. performance! */
121 XBT_INFO("Load: %f > threshold: %f --> changed to pstate %i", load, freq_up_threshold_, 0);
123 /* The actual implementation uses a formula here: (See Kernel file cpufreq_ondemand.c:158)
125 * freq_next = min_f + load * (max_f - min_f) / 100
127 * So they assume that frequency increases by 100 MHz. We will just use
128 * lowest_pstate - load*pstatesCount()
130 int max_pstate = get_host()->get_pstate_count() - 1;
131 // Load is now < freq_up_threshold; exclude pstate 0 (the fastest)
132 // because pstate 0 can only be selected if load > freq_up_threshold_
133 int new_pstate = max_pstate - load * (max_pstate + 1);
134 get_host()->set_pstate(new_pstate);
136 XBT_DEBUG("Load: %f < threshold: %f --> changed to pstate %i", load, freq_up_threshold_, new_pstate);
142 * This is the conservative governor, which is very similar to the
143 * OnDemand governor. The Linux Kernel Documentation describes it
144 * very well, see https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt:
146 * > The CPUfreq governor "conservative", much like the "ondemand"
147 * > governor, sets the CPU frequency depending on the current usage. It
148 * > differs in behaviour in that it gracefully increases and decreases the
149 * > CPU speed rather than jumping to max speed the moment there is any load
150 * > on the CPU. This behaviour is more suitable in a battery powered
153 class Conservative : public Governor {
154 double freq_up_threshold_ = .8;
155 double freq_down_threshold_ = .2;
158 explicit Conservative(simgrid::s4u::Host* ptr) : Governor(ptr) {}
159 virtual std::string get_name() override { return "Conservative"; }
161 virtual void update() override
163 double load = get_host()->get_core_count() * sg_host_get_avg_load(get_host());
164 int pstate = get_host()->get_pstate();
165 sg_host_load_reset(get_host()); // Only consider the period between two calls to this method!
167 if (load > freq_up_threshold_) {
169 get_host()->set_pstate(pstate - 1);
170 XBT_INFO("Load: %f > threshold: %f -> increasing performance to pstate %d", load, freq_up_threshold_,
173 XBT_DEBUG("Load: %f > threshold: %f -> but cannot speed up even more, already in highest pstate %d", load,
174 freq_up_threshold_, pstate);
176 } else if (load < freq_down_threshold_) {
177 int max_pstate = get_host()->get_pstate_count() - 1;
178 if (pstate != max_pstate) { // Are we in the slowest pstate already?
179 get_host()->set_pstate(pstate + 1);
180 XBT_INFO("Load: %f < threshold: %f -> slowing down to pstate %d", load, freq_down_threshold_, pstate + 1);
182 XBT_DEBUG("Load: %f < threshold: %f -> cannot slow down even more, already in slowest pstate %d", load,
183 freq_down_threshold_, pstate);
190 * Add this to your host tag:
191 * - \<prop id="plugin/dvfs/governor" value="performance" /\>
193 * Valid values as of now are: performance, powersave, ondemand, conservative
194 * It doesn't matter if you use uppercase or lowercase.
196 * For the sampling rate, use this:
198 * - \<prop id="plugin/dvfs/sampling_rate" value="2" /\>
200 * This will run the update() method of the specified governor every 2 seconds
203 * These properties can also be used within the \<config\> tag to configure
204 * these values globally. Using them within the \<host\> will overwrite this
205 * global configuration
209 static simgrid::xbt::Extension<simgrid::s4u::Host, HostDvfs> EXTENSION_ID;
211 explicit HostDvfs(simgrid::s4u::Host*){};
212 ~HostDvfs() = default;
215 simgrid::xbt::Extension<simgrid::s4u::Host, HostDvfs> HostDvfs::EXTENSION_ID;
218 } // namespace plugin
219 } // namespace simgrid
221 using simgrid::plugin::dvfs::HostDvfs;
223 /* **************************** events callback *************************** */
224 static void on_host_added(simgrid::s4u::Host& host)
226 if (dynamic_cast<simgrid::s4u::VirtualMachine*>(&host)) // Ignore virtual machines
229 std::string name = std::string("dvfs-daemon-") + host.get_cname();
230 simgrid::s4u::ActorPtr daemon = simgrid::s4u::Actor::create(name.c_str(), &host, []() {
232 * This lambda function is the function the actor (daemon) will execute
233 * all the time - in the case of the dvfs plugin, this controls when to
234 * lower/raise the frequency.
236 simgrid::s4u::ActorPtr daemon_proc = simgrid::s4u::Actor::self();
238 XBT_DEBUG("DVFS process on %s is a daemon: %d", daemon_proc->get_host()->get_cname(), daemon_proc->is_daemon());
240 std::string dvfs_governor;
241 const char* host_conf = daemon_proc->get_host()->get_property(property_governor);
242 if (host_conf != nullptr) {
243 dvfs_governor = std::string(daemon_proc->get_host()->get_property(property_governor));
244 boost::algorithm::to_lower(dvfs_governor);
246 dvfs_governor = simgrid::config::get_value<std::string>(property_governor);
247 boost::algorithm::to_lower(dvfs_governor);
250 auto governor = [&dvfs_governor, &daemon_proc]() {
251 if (dvfs_governor == "conservative") {
252 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
253 new simgrid::plugin::dvfs::Conservative(daemon_proc->get_host()));
254 } else if (dvfs_governor == "ondemand") {
255 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
256 new simgrid::plugin::dvfs::OnDemand(daemon_proc->get_host()));
257 } else if (dvfs_governor == "performance") {
258 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
259 new simgrid::plugin::dvfs::Performance(daemon_proc->get_host()));
260 } else if (dvfs_governor == "powersave") {
261 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
262 new simgrid::plugin::dvfs::Powersave(daemon_proc->get_host()));
264 XBT_CRITICAL("No governor specified for host %s, falling back to Performance",
265 daemon_proc->get_host()->get_cname());
266 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
267 new simgrid::plugin::dvfs::Performance(daemon_proc->get_host()));
272 // Sleep *before* updating; important for startup (i.e., t = 0).
273 // In the beginning, we want to go with the pstates specified in the platform file
274 // (so we sleep first)
275 simgrid::s4u::this_actor::sleep_for(governor->get_sampling_rate());
277 XBT_DEBUG("Governor (%s) just updated!", governor->get_name().c_str());
280 XBT_WARN("I should have never reached this point: daemons should be killed when all regular processes are done");
284 // This call must be placed in this function. Otherwise, the daemonize() call comes too late and
285 // SMPI will take this process as an MPI process!
289 /* **************************** Public interface *************************** */
291 /** \ingroup SURF_plugin_load
292 * \brief Initializes the HostDvfs plugin
293 * \details The HostDvfs plugin provides an API to get the current load of each host.
295 void sg_host_dvfs_plugin_init()
297 if (HostDvfs::EXTENSION_ID.valid())
300 HostDvfs::EXTENSION_ID = simgrid::s4u::Host::extension_create<HostDvfs>();
302 sg_host_load_plugin_init();
304 simgrid::s4u::Host::on_creation.connect(&on_host_added);
305 simgrid::config::declare_flag<double>(
306 property_sampling_rate, "How often should the dvfs plugin check whether the frequency needs to be changed?", 0.1);
307 simgrid::config::declare_flag<std::string>(
308 property_governor, "Which Governor should be used that adapts the CPU frequency?", "performance");