diff options
| -rw-r--r-- | base/sys_info_posix.cc | 17 | ||||
| -rw-r--r-- | chrome/browser/extensions/api/system_cpu/cpu_info_provider_linux.cc | 47 |
2 files changed, 37 insertions, 27 deletions
diff --git a/base/sys_info_posix.cc b/base/sys_info_posix.cc index c201ae1..3d49bf9 100644 --- a/base/sys_info_posix.cc +++ b/base/sys_info_posix.cc @@ -30,9 +30,20 @@ namespace { #if !defined(OS_OPENBSD) int NumberOfProcessors() { - // It seems that sysconf returns the number of "logical" processors on both - // Mac and Linux. So we get the number of "online logical" processors. - long res = sysconf(_SC_NPROCESSORS_ONLN); + // sysconf returns the number of "logical" (not "physical") processors on both + // Mac and Linux. So we get the number of max available "logical" processors. + // + // Note that the number of "currently online" processors may be fewer than the + // returned value of NumberOfProcessors(). On some platforms, the kernel may + // make some processors offline intermittently, to save power when system + // loading is low. + // + // One common use case that needs to know the processor count is to create + // optimal number of threads for optimization. It should make plan according + // to the number of "max available" processors instead of "currently online" + // ones. The kernel should be smart enough to make all processors online when + // it has sufficient number of threads waiting to run. + long res = sysconf(_SC_NPROCESSORS_CONF); if (res == -1) { NOTREACHED(); return 1; diff --git a/chrome/browser/extensions/api/system_cpu/cpu_info_provider_linux.cc b/chrome/browser/extensions/api/system_cpu/cpu_info_provider_linux.cc index 7885414..927f581 100644 --- a/chrome/browser/extensions/api/system_cpu/cpu_info_provider_linux.cc +++ b/chrome/browser/extensions/api/system_cpu/cpu_info_provider_linux.cc @@ -22,6 +22,17 @@ bool CpuInfoProvider::QueryCpuTimePerProcessor( std::vector<linked_ptr<api::system_cpu::ProcessorInfo> >* infos) { DCHECK(infos); + // WARNING: this method may return incomplete data because some processors may + // be brought offline at runtime. /proc/stat does not report statistics of + // offline processors. CPU usages of offline processors will be filled with + // zeros. + // + // An example of output of /proc/stat when processor 0 and 3 are online, but + // processor 1 and 2 are offline: + // + // cpu 145292 20018 83444 1485410 995 44 3578 0 0 0 + // cpu0 138060 19947 78350 1479514 570 44 3576 0 0 0 + // cpu3 2033 32 1075 1400 52 0 1 0 0 0 std::string contents; if (!base::ReadFileToString(base::FilePath(kProcStat), &contents)) return false; @@ -32,37 +43,25 @@ bool CpuInfoProvider::QueryCpuTimePerProcessor( // Skip the first line because it is just an aggregated number of // all cpuN lines. std::getline(iss, line); - size_t i = 0; while (std::getline(iss, line)) { if (line.compare(0, 3, "cpu") != 0) continue; - // The number of entries in /proc/stat may mismatch the size of infos - // because the number of online processors may change after the value has - // been decided in CpuInfoProvider::QueryInfo(). - // - // TODO(jchuang): fix the fail case by using the number of configured - // processors instead of online processors. - if (i == infos->size()) { - LOG(ERROR) << "Got more entries in /proc/stat than online CPUs"; - return false; - } - uint64 user = 0, nice = 0, sys = 0, idle = 0; + uint32 pindex = 0; int vals = sscanf(line.c_str(), - "%*s %" PRIu64 " %" PRIu64 " %" PRIu64 " %" PRIu64, - &user, &nice, &sys, &idle); - DCHECK_EQ(4, vals); + "cpu%" PRIu32 " %" PRIu64 " %" PRIu64 " %" PRIu64 " %" PRIu64, + &pindex, &user, &nice, &sys, &idle); + if (vals != 5 || pindex >= infos->size()) { + NOTREACHED(); + return false; + } - infos->at(i)->usage.kernel = static_cast<double>(sys); - infos->at(i)->usage.user = static_cast<double>(user + nice); - infos->at(i)->usage.idle = static_cast<double>(idle); - infos->at(i)->usage.total = static_cast<double>(sys + user + nice + idle); - ++i; - } - if (i < infos->size()) { - LOG(ERROR) << "Got fewer entries in /proc/stat than online CPUs"; - return false; + infos->at(pindex)->usage.kernel = static_cast<double>(sys); + infos->at(pindex)->usage.user = static_cast<double>(user + nice); + infos->at(pindex)->usage.idle = static_cast<double>(idle); + infos->at(pindex)->usage.total = static_cast<double>(sys + user + + nice + idle); } return true; |