101 lines
2.8 KiB
C++
101 lines
2.8 KiB
C++
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// Software Name : cppuprofile
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// SPDX-FileCopyrightText: Copyright (c) 2022 Orange
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// SPDX-License-Identifier: BSD-3-Clause
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//
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// This software is distributed under the BSD License;
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// see the LICENSE file for more details.
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//
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// Author: Cédric CHEDALEUX <cedric.chedaleux@orange.com> et al.
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#include "cpumonitor.h"
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#include <fstream>
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#include <sstream>
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using namespace std;
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uprofile::CpuMonitor::CpuMonitor() :
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m_nbCpus(getNumberOfCPUCores())
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{
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m_lastIdleTimes.resize(m_nbCpus, 0);
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m_lastTotalTimes.resize(m_nbCpus, 0);
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}
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uprofile::CpuMonitor::~CpuMonitor()
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{
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}
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size_t uprofile::CpuMonitor::getNumberOfCPUCores()
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{
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size_t nbCores = 0;
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#if defined(__linux__)
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ifstream meminfo("/proc/cpuinfo");
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string str;
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while (getline(meminfo, str)) {
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if (str.rfind("processor", 0) == 0) {
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nbCores++;
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}
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}
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#endif
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return nbCores;
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}
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void uprofile::CpuMonitor::extractCpuTimes(const string& cpuInfo, size_t& idleTime, size_t& totalTime)
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{
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// Remove 'cpu<index' word and
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// extract the idle time and sum all other times
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size_t spacePos = cpuInfo.find(' ');
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if (spacePos == string::npos) {
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return;
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}
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stringstream times(cpuInfo.substr(spacePos + 1));
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int index = 0;
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for (size_t time; times >> time; ++index) {
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if (index == 3) { // idle time i s the 4th param
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idleTime = time;
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}
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totalTime += time;
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}
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}
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vector<float> uprofile::CpuMonitor::getUsage()
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{
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vector<float> usages;
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#if defined(__linux__)
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ifstream procStat("/proc/stat");
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// /proc/stat dumps the following info:
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// user nice system idle iowait irq softirq
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// cpu 2255 34 2290 22625563 6290 127 456
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// cpu0 1132 34 1441 11311718 3675 127 438
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// cpu1 1123 0 849 11313845 2614 0 18
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// ...
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// Each numbers represents the amount of time the CPU has spent performing
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// different kind of work
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for (size_t cpuIndex = 0; cpuIndex < m_nbCpus; ++cpuIndex) {
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string cpuName("cpu");
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cpuName += to_string(cpuIndex);
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// Look in /proc/stack the CPU info
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string line;
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while (getline(procStat, line)) {
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if (line.find(cpuName) != std::string::npos) {
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size_t idleTime = 0, totalTime = 0;
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extractCpuTimes(line, idleTime, totalTime);
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// To compute CPU load, we compute the time the CPU has been idle since the last read.
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float cpuLoad = 100.0 * (1.0 - (float)(idleTime - m_lastIdleTimes[cpuIndex]) / (totalTime - m_lastTotalTimes[cpuIndex]));
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usages.push_back(cpuLoad);
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// Save the times value for the next read
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m_lastIdleTimes[cpuIndex] = idleTime;
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m_lastTotalTimes[cpuIndex] = totalTime;
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break;
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}
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}
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}
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#endif
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return usages;
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}
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