Fix getting the CPU frequency on OS X
diff --git a/src/sysinfo.cc b/src/sysinfo.cc
index 4869472..dd1e663 100644
--- a/src/sysinfo.cc
+++ b/src/sysinfo.cc
@@ -280,29 +280,24 @@
// group
#elif defined BENCHMARK_OS_MACOSX
- // returning "mach time units" per second. the current number of elapsed
- // mach time units can be found by calling uint64 mach_absolute_time();
- // while not as precise as actual CPU cycles, it is accurate in the face
- // of CPU frequency scaling and multi-cpu/core machines.
- // Our mac users have these types of machines, and accuracy
- // (i.e. correctness) trumps precision.
- // See cycleclock.h: CycleClock::Now(), which returns number of mach time
- // units on Mac OS X.
- mach_timebase_info_data_t timebase_info;
- mach_timebase_info(&timebase_info);
- double mach_time_units_per_nanosecond =
- static_cast<double>(timebase_info.denom) /
- static_cast<double>(timebase_info.numer);
- cpuinfo_cycles_per_second = mach_time_units_per_nanosecond * 1e9;
-
- int num_cpus = 0;
+ int32_t num_cpus = 0;
size_t size = sizeof(num_cpus);
- int numcpus_name[] = {CTL_HW, HW_NCPU};
- if (::sysctl(numcpus_name, arraysize(numcpus_name), &num_cpus, &size, nullptr,
- 0) == 0 &&
- (size == sizeof(num_cpus)))
+ if (::sysctlbyname("hw.ncpu", &num_cpus, &size, nullptr, 0) == 0 &&
+ (size == sizeof(num_cpus))) {
cpuinfo_num_cpus = num_cpus;
-
+ } else {
+ fprintf(stderr, "%s\n", strerror(errno));
+ std::exit(EXIT_FAILURE);
+ }
+ int64_t cpu_freq = 0;
+ size = sizeof(cpu_freq);
+ if (::sysctlbyname("hw.cpufrequency", &cpu_freq, &size, nullptr, 0) == 0 &&
+ (size == sizeof(cpu_freq))) {
+ cpuinfo_cycles_per_second = cpu_freq;
+ } else {
+ fprintf(stderr, "%s\n", strerror(errno));
+ std::exit(EXIT_FAILURE);
+ }
#else
// Generic cycles per second counter
cpuinfo_cycles_per_second = static_cast<double>(EstimateCyclesPerSecond());
