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Remove /proc/cpuinfo fallback path ()

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AIX, WASM (fork of musl for libc) and a few others should now use the sysconf
path. /proc is not portable and cpuinfo is Linux specific. It does not work
anywhere else.
This commit is contained in:
Brad Smith 2025-02-10 12:34:29 -05:00 committed by GitHub
parent 9d8201efd4
commit da9d68953b
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GPG Key ID: B5690EEEBB952194
1 changed files with 4 additions and 48 deletions

52
src/sysinfo.cc
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@ -497,6 +497,7 @@ int GetNumCPUsImpl() {
}
return hardware_threads.max_hthreads;
#elif defined(BENCHMARK_HAS_SYSCTL)
// *BSD, macOS
int num_cpu = -1;
constexpr auto* hwncpu =
#if defined BENCHMARK_OS_MACOSX
@ -509,6 +510,7 @@ int GetNumCPUsImpl() {
if (GetSysctl(hwncpu, &num_cpu)) return num_cpu;
PrintErrorAndDie("Err: ", strerror(errno));
#elif defined(_SC_NPROCESSORS_ONLN)
// Linux, Solaris, AIX, Haiku, WASM, etc.
// Returns -1 in case of a failure.
int num_cpu = static_cast<int>(sysconf(_SC_NPROCESSORS_ONLN));
if (num_cpu < 0) {
@ -517,54 +519,8 @@ int GetNumCPUsImpl() {
}
return num_cpu;
#else
// Fallback for platforms (such as WASM) that aren't covered above.
int num_cpus = 0;
int max_id = -1;
std::ifstream f("/proc/cpuinfo");
if (!f.is_open()) {
std::cerr << "Failed to open /proc/cpuinfo\n";
return -1;
}
#if defined(__alpha__)
const std::string Key = "cpus detected";
#else
const std::string Key = "processor";
#endif
std::string ln;
while (std::getline(f, ln)) {
if (ln.empty()) continue;
std::size_t split_idx = ln.find(':');
std::string value;
#if defined(__s390__)
// s390 has another format in /proc/cpuinfo
// it needs to be parsed differently
if (split_idx != std::string::npos)
value = ln.substr(Key.size() + 1, split_idx - Key.size() - 1);
#else
if (split_idx != std::string::npos) value = ln.substr(split_idx + 1);
#endif
if (ln.size() >= Key.size() && ln.compare(0, Key.size(), Key) == 0) {
num_cpus++;
if (!value.empty()) {
const int cur_id = benchmark::stoi(value);
max_id = std::max(cur_id, max_id);
}
}
}
if (f.bad()) {
PrintErrorAndDie("Failure reading /proc/cpuinfo");
}
if (!f.eof()) {
PrintErrorAndDie("Failed to read to end of /proc/cpuinfo");
}
f.close();
if ((max_id + 1) != num_cpus) {
fprintf(stderr,
"CPU ID assignments in /proc/cpuinfo seem messed up."
" This is usually caused by a bad BIOS.\n");
}
return num_cpus;
// Fallback, no other API exists.
return -1;
#endif
BENCHMARK_UNREACHABLE();
}