tools/profiler/core/ProfilerCPUFreq-linux-android.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "ProfilerCPUFreq.h"
   6 #include "nsThreadUtils.h"
   7 #include <fcntl.h>
   8 #include <unistd.h>
   9
  10 ProfilerCPUFreq::ProfilerCPUFreq() {
  11   if (!mCPUCounters.resize(mozilla::GetNumberOfProcessors())) {
  12     NS_WARNING("failing to resize the mCPUCounters vector");
  13     return;
  14   }
  15
  16   for (unsigned cpuId = 0; cpuId < mCPUCounters.length(); ++cpuId) {
  17     const size_t buf_sz = 64;
  18     char buf[buf_sz];
  19     int rv = sprintf(
  20         buf, "/sys/devices/system/cpu/cpu%u/cpufreq/scaling_cur_freq", cpuId);
  21     if (NS_WARN_IF(rv < 0)) {
  22       continue;
  23     }
  24
  25     int fd = open(buf, O_RDONLY);
  26     if (NS_WARN_IF(!fd)) {
  27       continue;
  28     }
  29
  30     mCPUCounters[cpuId].fd = fd;
  31   }
  32 }
  33
  34 ProfilerCPUFreq::~ProfilerCPUFreq() {
  35   for (CPUCounterInfo& CPUCounter : mCPUCounters) {
  36     int fd = CPUCounter.fd;
  37     if (NS_WARN_IF(!fd)) {
  38       continue;
  39     }
  40     close(fd);
  41     CPUCounter.fd = 0;
  42   }
  43 }
  44
  45 uint32_t ProfilerCPUFreq::GetCPUSpeedMHz(unsigned cpuId) {
  46   MOZ_ASSERT(cpuId < mCPUCounters.length());
  47   int fd = mCPUCounters[cpuId].fd;
  48   if (NS_WARN_IF(!fd)) {
  49     return 0;
  50   }
  51
  52   long rv = lseek(fd, 0, SEEK_SET);
  53   if (NS_WARN_IF(rv < 0)) {
  54     return 0;
  55   }
  56
  57   const size_t buf_sz = 64;
  58   char buf[buf_sz];
  59   rv = read(fd, buf, buf_sz);
  60   if (NS_WARN_IF(rv < 0)) {
  61     return 0;
  62   }
  63
  64   int cpufreq = 0;
  65   rv = sscanf(buf, "%u", &cpufreq);
  66   if (NS_WARN_IF(rv != 1)) {
  67     return 0;
  68   }
  69
  70   // Convert kHz to MHz, rounding to the nearst 10Mhz, to ignore tiny
  71   // variations that are likely due to rounding errors.
  72   return uint32_t(cpufreq / 10000) * 10;
  73 }