hal/cocoa/CocoaHeterogeneousCpuInfo.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
   6
   7 #include "Hal.h"
   8 #include "HalTypes.h"
   9 #include <sys/types.h>
  10 #include <sys/sysctl.h>
  11 #include "mozilla/BitSet.h"
  12
  13 namespace mozilla::hal_impl {
  14
  15 mozilla::Maybe<hal::HeterogeneousCpuInfo> CreateHeterogeneousCpuInfo() {
  16 #ifdef __aarch64__
  17   // As of now on Apple Silicon the number of *.logicalcpu_max is the same as
  18   // *.physicalcpu_max.
  19   size_t len = sizeof(uint32_t);
  20   uint32_t pCores = 0;
  21   if (sysctlbyname("hw.perflevel0.logicalcpu_max", &pCores, &len, nullptr, 0)) {
  22     return Nothing();
  23   }
  24
  25   len = sizeof(uint32_t);
  26   uint32_t eCores = 0;
  27   if (sysctlbyname("hw.perflevel1.logicalcpu_max", &eCores, &len, nullptr, 0)) {
  28     return Nothing();
  29   }
  30
  31   hal::HeterogeneousCpuInfo info;
  32   info.mTotalNumCpus = pCores + eCores;
  33
  34   // The API has currently a limit how many cpu cores it can tell about.
  35   for (uint32_t i = 0; i < hal::HeterogeneousCpuInfo::MAX_CPUS; ++i) {
  36     if (pCores) {
  37       --pCores;
  38       info.mBigCpus[i] = true;
  39     } else if (eCores) {
  40       --eCores;
  41       info.mLittleCpus[i] = true;
  42     } else {
  43       break;
  44     }
  45   }
  46
  47   return Some(info);
  48 #else
  49   return Nothing();
  50 #endif
  51 }
  52
  53 const Maybe<hal::HeterogeneousCpuInfo>& GetHeterogeneousCpuInfo() {
  54   static const Maybe<hal::HeterogeneousCpuInfo> cpuInfo =
  55       CreateHeterogeneousCpuInfo();
  56   return cpuInfo;
  57 }
  58
  59 }  // namespace mozilla::hal_impl