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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/system/sys_info.h"
#include <sys/sysctl.h>
#include "base/strings/stringprintf.h"
#include "base/system/sys_info_internal.h"
namespace base {
namespace internal {
// Queries sysctlbyname() for the given key and returns the 32 bit integer value
// from the system or std::nullopt on failure.
// https://github.com/apple/darwin-xnu/blob/2ff845c2e033bd0ff64b5b6aa6063a1f8f65aa32/bsd/sys/sysctl.h#L1224-L1225
std::optional<int> GetSysctlIntValue(const char* key_name) {
int value;
size_t len = sizeof(value);
if (sysctlbyname(key_name, &value, &len, nullptr, 0) != 0) {
return std::nullopt;
}
DCHECK_EQ(len, sizeof(value));
return value;
}
} // namespace internal
// static
int SysInfo::NumberOfEfficientProcessorsImpl() {
int num_perf_levels =
internal::GetSysctlIntValue("hw.nperflevels").value_or(1);
if (num_perf_levels == 1) {
return 0;
}
DCHECK_GE(num_perf_levels, 2);
// Lower values of perflevel indicate higher-performance core types. See
// https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_system_capabilities?changes=l__5
int num_of_efficient_processors =
internal::GetSysctlIntValue(
StringPrintf("hw.perflevel%d.logicalcpu", num_perf_levels - 1)
.c_str())
.value_or(0);
DCHECK_GE(num_of_efficient_processors, 0);
return num_of_efficient_processors;
}
// static
uint64_t SysInfo::AmountOfPhysicalMemoryImpl() {
uint64_t physical_memory;
size_t size = sizeof(physical_memory);
int rv = sysctlbyname("hw.memsize", &physical_memory, &size, nullptr, 0);
PCHECK(rv == 0) << "sysctlbyname(\"hw.memsize\")";
return physical_memory;
}
} // namespace base
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