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;
36 explicit Governor(simgrid::s4u::Host* ptr) : host(ptr) { init(); }
37 virtual ~Governor() = default;
41 const char* local_sampling_rate_config = host->getProperty(property_sampling_rate);
42 double global_sampling_rate_config = xbt_cfg_get_double(property_sampling_rate);
43 if (local_sampling_rate_config != nullptr) {
44 sampling_rate = std::stod(local_sampling_rate_config);
46 sampling_rate = global_sampling_rate_config;
50 virtual void update() = 0;
51 virtual std::string getName() = 0;
52 double samplingRate() { return sampling_rate; }
56 * The linux kernel doc describes this governor as follows:
57 * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
59 * > The CPUfreq governor "performance" sets the CPU statically to the
60 * > highest frequency within the borders of scaling_min_freq and
63 * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency.
65 class Performance : public Governor {
67 explicit Performance(simgrid::s4u::Host* ptr) : Governor(ptr) {}
69 void update() override { host->setPstate(0); }
70 std::string getName() override { return "Performance"; }
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 "powersave" sets the CPU statically to the
78 * > lowest 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 Powersave : public Governor {
85 explicit Powersave(simgrid::s4u::Host* ptr) : Governor(ptr) {}
87 void update() override { host->setPstate(host->getPstatesCount() - 1); }
88 std::string getName() override { return "Powersave"; }
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 "ondemand" sets the CPU frequency depending on the
96 * > current system load. [...] when triggered, cpufreq checks
97 * > the CPU-usage statistics over the last period and the governor sets the
100 class OnDemand : public Governor {
102 * See https://elixir.bootlin.com/linux/v4.15.4/source/drivers/cpufreq/cpufreq_ondemand.c
103 * DEF_FREQUENCY_UP_THRESHOLD and od_update()
105 double freq_up_threshold = 0.80;
108 explicit OnDemand(simgrid::s4u::Host* ptr) : Governor(ptr) {}
110 std::string getName() override { return "OnDemand"; }
111 void update() override
113 double load = host->getCoreCount() * sg_host_get_avg_load(host);
114 sg_host_load_reset(host); // Only consider the period between two calls to this method!
116 if (load > freq_up_threshold) {
117 host->setPstate(0); /* Run at max. performance! */
118 XBT_INFO("Load: %f > threshold: %f --> changed to pstate %i", load, freq_up_threshold, 0);
120 /* The actual implementation uses a formula here: (See Kernel file cpufreq_ondemand.c:158)
122 * freq_next = min_f + load * (max_f - min_f) / 100
124 * So they assume that frequency increases by 100 MHz. We will just use
125 * lowest_pstate - load*pstatesCount()
127 int max_pstate = host->getPstatesCount() - 1;
128 // Load is now < freq_up_threshold; exclude pstate 0 (the fastest)
129 // because pstate 0 can only be selected if load > freq_up_threshold
130 int new_pstate = max_pstate - load * (max_pstate + 1);
131 host->setPstate(new_pstate);
133 XBT_DEBUG("Load: %f < threshold: %f --> changed to pstate %i", load, freq_up_threshold, new_pstate);
139 * This is the conservative governor, which is very similar to the
140 * OnDemand governor. The Linux Kernel Documentation describes it
141 * very well, see https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt:
143 * > The CPUfreq governor "conservative", much like the "ondemand"
144 * > governor, sets the CPU frequency depending on the current usage. It
145 * > differs in behaviour in that it gracefully increases and decreases the
146 * > CPU speed rather than jumping to max speed the moment there is any load
147 * > on the CPU. This behaviour is more suitable in a battery powered
150 class Conservative : public Governor {
151 double freq_up_threshold = .8;
152 double freq_down_threshold = .2;
155 explicit Conservative(simgrid::s4u::Host* ptr) : Governor(ptr) {}
157 virtual std::string getName() override { return "Conservative"; }
158 virtual void update() override
160 double load = host->getCoreCount() * sg_host_get_avg_load(host);
161 int pstate = host->getPstate();
162 sg_host_load_reset(host); // Only consider the period between two calls to this method!
164 if (load > freq_up_threshold) {
166 host->setPstate(pstate - 1);
167 XBT_INFO("Load: %f > threshold: %f -> increasing performance to pstate %d", load, freq_up_threshold, pstate - 1);
170 XBT_DEBUG("Load: %f > threshold: %f -> but cannot speed up even more, already in highest pstate %d", load, freq_up_threshold, pstate);
172 } else if (load < freq_down_threshold) {
173 int max_pstate = host->getPstatesCount() - 1;
174 if (pstate != max_pstate) { // Are we in the slowest pstate already?
175 host->setPstate(pstate + 1);
176 XBT_INFO("Load: %f < threshold: %f -> slowing down to pstate %d", load, freq_down_threshold, pstate + 1);
179 XBT_DEBUG("Load: %f < threshold: %f -> cannot slow down even more, already in slowest pstate %d", load, freq_down_threshold, pstate);
186 * Add this to your host tag:
187 * - <prop id="plugin/dvfs/governor" value="performance" />
189 * Valid values as of now are: performance, powersave, ondemand, conservative
190 * It doesn't matter if you use uppercase or lowercase.
192 * For the sampling rate, use this:
194 * - <prop id="plugin/dvfs/sampling_rate" value="2" />
196 * This will run the update() method of the specified governor every 2 seconds
199 * These properties can also be used within the <config> tag to configure
200 * these values globally. Using them within the <host> will overwrite this
201 * global configuration
205 static simgrid::xbt::Extension<simgrid::s4u::Host, HostDvfs> EXTENSION_ID;
207 explicit HostDvfs(simgrid::s4u::Host*);
211 simgrid::xbt::Extension<simgrid::s4u::Host, HostDvfs> HostDvfs::EXTENSION_ID;
213 HostDvfs::HostDvfs(simgrid::s4u::Host* ptr) {}
215 HostDvfs::~HostDvfs() = default;
220 using simgrid::plugin::dvfs::HostDvfs;
222 /* **************************** events callback *************************** */
223 static void on_host_added(simgrid::s4u::Host& host)
225 if (dynamic_cast<simgrid::s4u::VirtualMachine*>(&host)) // Ignore virtual machines
228 std::string name = std::string("dvfs-daemon-") + host.get_cname();
229 simgrid::s4u::ActorPtr daemon = simgrid::s4u::Actor::create(name.c_str(), &host, []() {
231 * This lambda function is the function the actor (daemon) will execute
232 * all the time - in the case of the dvfs plugin, this controls when to
233 * lower/raise the frequency.
235 simgrid::s4u::ActorPtr daemon_proc = simgrid::s4u::Actor::self();
237 XBT_DEBUG("DVFS process on %s is a daemon: %d", daemon_proc->get_host()->get_cname(), daemon_proc->is_daemon());
239 std::string dvfs_governor;
240 const char* host_conf = daemon_proc->get_host()->getProperty(property_governor);
241 if (host_conf != nullptr) {
242 dvfs_governor = std::string(daemon_proc->get_host()->getProperty(property_governor));
243 boost::algorithm::to_lower(dvfs_governor);
245 dvfs_governor = xbt_cfg_get_string(property_governor);
246 boost::algorithm::to_lower(dvfs_governor);
249 auto governor = [&dvfs_governor, &daemon_proc]() {
250 if (dvfs_governor == "conservative") {
251 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
252 new simgrid::plugin::dvfs::Conservative(daemon_proc->get_host()));
253 } else if (dvfs_governor == "ondemand") {
254 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
255 new simgrid::plugin::dvfs::OnDemand(daemon_proc->get_host()));
256 } else if (dvfs_governor == "performance") {
257 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
258 new simgrid::plugin::dvfs::Performance(daemon_proc->get_host()));
259 } else if (dvfs_governor == "powersave") {
260 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
261 new simgrid::plugin::dvfs::Powersave(daemon_proc->get_host()));
263 XBT_CRITICAL("No governor specified for host %s, falling back to Performance",
264 daemon_proc->get_host()->get_cname());
265 return std::unique_ptr<simgrid::plugin::dvfs::Governor>(
266 new simgrid::plugin::dvfs::Performance(daemon_proc->get_host()));
271 // Sleep *before* updating; important for startup (i.e., t = 0).
272 // In the beginning, we want to go with the pstates specified in the platform file
273 // (so we sleep first)
274 simgrid::s4u::this_actor::sleep_for(governor->samplingRate());
276 XBT_DEBUG("Governor (%s) just updated!", governor->getName().c_str());
279 XBT_WARN("I should have never reached this point: daemons should be killed when all regular processes are done");
283 // This call must be placed in this function. Otherweise, the daemonize() call comes too late and
284 // SMPI will take this process as an MPI process!
288 /* **************************** Public interface *************************** */
290 /** \ingroup SURF_plugin_load
291 * \brief Initializes the HostDvfs plugin
292 * \details The HostDvfs plugin provides an API to get the current load of each host.
294 void sg_host_dvfs_plugin_init()
296 if (HostDvfs::EXTENSION_ID.valid())
299 HostDvfs::EXTENSION_ID = simgrid::s4u::Host::extension_create<HostDvfs>();
301 sg_host_load_plugin_init();
303 simgrid::s4u::Host::onCreation.connect(&on_host_added);
304 xbt_cfg_register_double(property_sampling_rate, 0.1, nullptr,
305 "How often should the dvfs plugin check whether the frequency needs to be changed?");
306 xbt_cfg_register_string(property_governor, "performance", nullptr,
307 "Which Governor should be used that adapts the CPU frequency?");