X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/4abb5993262c94ae6ec8aab815fcd703764df371..5f9b6053027484ea411db0d1ee44ac258c9816f1:/src/surf/plugins/host_dvfs.cpp diff --git a/src/surf/plugins/host_dvfs.cpp b/src/surf/plugins/host_dvfs.cpp index 5d518c7e2e..555d67ae53 100644 --- a/src/surf/plugins/host_dvfs.cpp +++ b/src/surf/plugins/host_dvfs.cpp @@ -12,7 +12,6 @@ #include #include #include -#include #include #include #include @@ -61,6 +60,16 @@ public: double samplingRate() { return sampling_rate; } }; +/** + * The linux kernel doc describes this governor as follows: + * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt + * + * > The CPUfreq governor "performance" sets the CPU statically to the + * > highest frequency within the borders of scaling_min_freq and + * > scaling_max_freq. + * + * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency. + */ class Performance : public Governor { public: explicit Performance(simgrid::s4u::Host* ptr) : Governor(ptr) {} @@ -69,6 +78,16 @@ public: std::string getName() override { return "Performance"; } }; +/** + * The linux kernel doc describes this governor as follows: + * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt + * + * > The CPUfreq governor "powersave" sets the CPU statically to the + * > lowest frequency within the borders of scaling_min_freq and + * > scaling_max_freq. + * + * We do not support scaling_min_freq/scaling_max_freq -- we just pick the lowest frequency. + */ class Powersave : public Governor { public: explicit Powersave(simgrid::s4u::Host* ptr) : Governor(ptr) {} @@ -77,8 +96,21 @@ public: std::string getName() override { return "Powersave"; } }; +/** + * The linux kernel doc describes this governor as follows: + * https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt + * + * > The CPUfreq governor "ondemand" sets the CPU frequency depending on the + * > current system load. [...] when triggered, cpufreq checks + * > the CPU-usage statistics over the last period and the governor sets the + * > CPU accordingly. + */ class OnDemand : public Governor { - double freq_up_threshold = 0.95; + /** + * See https://elixir.bootlin.com/linux/v4.15.4/source/drivers/cpufreq/cpufreq_ondemand.c + * DEF_FREQUENCY_UP_THRESHOLD and od_update() + */ + double freq_up_threshold = 0.80; public: explicit OnDemand(simgrid::s4u::Host* ptr) : Governor(ptr) {} @@ -86,12 +118,12 @@ public: std::string getName() override { return "OnDemand"; } void update() override { - double load = sg_host_get_current_load(host); + double load = host->getCoreCount() * sg_host_get_avg_load(host); + sg_host_load_reset(host); // Only consider the period between two calls to this method! - // FIXME I don't like that we multiply with the getCoreCount() just here... - if (load*host->getCoreCount() > freq_up_threshold) { + if (load > freq_up_threshold) { host->setPstate(0); /* Run at max. performance! */ - XBT_INFO("Load: %f > threshold: %f --> changed to pstate %i", load * host->getCoreCount(), freq_up_threshold, 0); + XBT_INFO("Load: %f > threshold: %f --> changed to pstate %i", load, freq_up_threshold, 0); } else { /* The actual implementation uses a formula here: (See Kernel file cpufreq_ondemand.c:158) * @@ -101,14 +133,28 @@ public: * lowest_pstate - load*pstatesCount() */ int max_pstate = host->getPstatesCount() - 1; - int new_pstate = max_pstate - load * max_pstate; + // Load is now < freq_up_threshold; exclude pstate 0 (the fastest) + // because pstate 0 can only be selected if load > freq_up_threshold + int new_pstate = max_pstate - load * (max_pstate + 1); host->setPstate(new_pstate); - XBT_DEBUG("Load: %f --> changed to pstate %i", load*host->getCoreCount(), new_pstate); + XBT_DEBUG("Load: %f < threshold: %f --> changed to pstate %i", load, freq_up_threshold, new_pstate); } } }; +/** + * This is the conservative governor, which is very similar to the + * OnDemand governor. The Linux Kernel Documentation describes it + * very well, see https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt: + * + * > The CPUfreq governor "conservative", much like the "ondemand" + * > governor, sets the CPU frequency depending on the current usage. It + * > differs in behaviour in that it gracefully increases and decreases the + * > CPU speed rather than jumping to max speed the moment there is any load + * > on the CPU. This behaviour is more suitable in a battery powered + * > environment. + */ class Conservative : public Governor { double freq_up_threshold = .8; double freq_down_threshold = .2; @@ -119,8 +165,9 @@ public: virtual std::string getName() override { return "Conservative"; } virtual void update() override { - double load = sg_host_get_current_load(host)*host->getCoreCount(); + double load = host->getCoreCount() * sg_host_get_avg_load(host); int pstate = host->getPstate(); + sg_host_load_reset(host); // Only consider the period between two calls to this method! if (load > freq_up_threshold) { if (pstate != 0) { @@ -143,6 +190,24 @@ public: } }; +/** + * Add this to your host tag: + * - + * + * Valid values as of now are: performance, powersave, ondemand, conservative + * It doesn't matter if you use uppercase or lowercase. + * + * For the sampling rate, use this: + * + * - + * + * This will run the update() method of the specified governor every 2 seconds + * on that host. + * + * These properties can also be used within the tag to configure + * these values globally. Using them within the will overwrite this + * global configuration + */ class HostDvfs { public: static simgrid::xbt::Extension EXTENSION_ID;