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[RUNTIME] Fix determination of big/little cores domains #13832

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merged 1 commit into from
Jan 24, 2023
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[RUNTIME] Fix determination of big/little cores domains #13832

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9 changes: 7 additions & 2 deletions src/runtime/threading_backend.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -306,7 +306,11 @@ class ThreadGroup::Impl {
int64_t cur_freq = 0;
#if defined(__linux__) || defined(__ANDROID__)
std::ostringstream filepath;
filepath << "/sys/devices/system/cpu/cpu" << i << "/cpufreq/scaling_max_freq";
// according to https://www.kernel.org/doc/Documentation/cpu-freq/user-guide.txt
// it's better to use cpuinfo_max_freq instead of scaling_max_freq for our
// purposes since scaling values can be changed dynamically according "policy limits"
// while we are looking for persistent definition of cores
filepath << "/sys/devices/system/cpu/cpu" << i << "/cpufreq/cpuinfo_max_freq";
std::ifstream ifs(filepath.str());
if (!ifs.fail()) {
if (!(ifs >> cur_freq)) {
Expand Down Expand Up @@ -335,7 +339,8 @@ class ThreadGroup::Impl {
}
}
if (big_count_ + little_count_ != static_cast<int>(sorted_order_.size())) {
LOG(WARNING) << "more than two frequencies detected!";
big_count_ = static_cast<int>(sorted_order_.size()) - little_count_;
LOG(WARNING) << "more than two frequencies detected! Forced big_count_ to " << big_count_;
}
}

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