1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "extensions/browser/api/system_cpu/cpu_info_provider.h" 6 7 #include <cstdio> 8 #include <sstream> 9 10 #include "base/files/file_util.h" 11 #include "base/format_macros.h" 12 13 namespace extensions { 14 15 namespace { 16 17 const char kProcStat[] = "/proc/stat"; 18 19 } // namespace 20 21 bool CpuInfoProvider::QueryCpuTimePerProcessor( 22 std::vector<linked_ptr<core_api::system_cpu::ProcessorInfo> >* infos) { 23 DCHECK(infos); 24 25 // WARNING: this method may return incomplete data because some processors may 26 // be brought offline at runtime. /proc/stat does not report statistics of 27 // offline processors. CPU usages of offline processors will be filled with 28 // zeros. 29 // 30 // An example of output of /proc/stat when processor 0 and 3 are online, but 31 // processor 1 and 2 are offline: 32 // 33 // cpu 145292 20018 83444 1485410 995 44 3578 0 0 0 34 // cpu0 138060 19947 78350 1479514 570 44 3576 0 0 0 35 // cpu3 2033 32 1075 1400 52 0 1 0 0 0 36 std::string contents; 37 if (!base::ReadFileToString(base::FilePath(kProcStat), &contents)) 38 return false; 39 40 std::istringstream iss(contents); 41 std::string line; 42 43 // Skip the first line because it is just an aggregated number of 44 // all cpuN lines. 45 std::getline(iss, line); 46 while (std::getline(iss, line)) { 47 if (line.compare(0, 3, "cpu") != 0) 48 continue; 49 50 uint64 user = 0, nice = 0, sys = 0, idle = 0; 51 uint32 pindex = 0; 52 int vals = 53 sscanf(line.c_str(), 54 "cpu%" PRIu32 " %" PRIu64 " %" PRIu64 " %" PRIu64 " %" PRIu64, 55 &pindex, 56 &user, 57 &nice, 58 &sys, 59 &idle); 60 if (vals != 5 || pindex >= infos->size()) { 61 NOTREACHED(); 62 return false; 63 } 64 65 infos->at(pindex)->usage.kernel = static_cast<double>(sys); 66 infos->at(pindex)->usage.user = static_cast<double>(user + nice); 67 infos->at(pindex)->usage.idle = static_cast<double>(idle); 68 infos->at(pindex)->usage.total = 69 static_cast<double>(sys + user + nice + idle); 70 } 71 72 return true; 73 } 74 75 } // namespace extensions 76