Commit a5fdbec9 authored by Florian Quèze's avatar Florian Quèze
Browse files

Bug 1822483 - Handle wraparounds in RAPL power counters on Intel Macs, r=dlrobertson. 

Differential Revision: https://phabricator.services.mozilla.com/D174065
parent 51b434ce

tools/profiler/core/PowerCounters-mac-amd64.cpp

+38 −17
Original line number Diff line number Diff line
@@ -163,6 +163,8 @@ class RaplDomain final : public BaseProfilerCount { 
  explicit RaplDomain(const char* aLabel, const char* aDescription)

      : BaseProfilerCount(aLabel, nullptr, nullptr, "power", aDescription),

        mSample(0),

        mEnergyStatusUnits(0),

        mWrapAroundCount(0),

        mIsSampleNew(false) {}



  CountSample Sample() override {
@@ -172,7 +174,11 @@ class RaplDomain final : public BaseProfilerCount { 
    // return values in picowatt-hour.

    constexpr double NANOJOULES_PER_JOULE = 1'000'000'000;

    constexpr double NANOJOULES_TO_PICOWATTHOUR = 3.6;

    result.count = mSample * NANOJOULES_PER_JOULE / NANOJOULES_TO_PICOWATTHOUR;



    uint64_t ticks = (uint64_t(mWrapAroundCount) << 32) + mSample;

    double joulesPerTick = (double)1 / (1 << mEnergyStatusUnits);

    result.count = static_cast<double>(ticks) * joulesPerTick *

                   NANOJOULES_PER_JOULE / NANOJOULES_TO_PICOWATTHOUR;



    result.number = 0;

    result.isSampleNew = mIsSampleNew;
@@ -180,15 +186,36 @@ class RaplDomain final : public BaseProfilerCount { 
    return result;

  }



  void AddSample(double aSample) {

  void AddSample(uint32_t aSample, uint32_t aEnergyStatusUnits) {

    if (aSample == mSample) {

      return;

    }



    mEnergyStatusUnits = aEnergyStatusUnits;



    if (aSample > mSample) {

      mIsSampleNew = true;

      mSample = aSample;

      return;

    }



    // Despite being returned in uint64_t fields, the power counter values

    // only use the lowest 32 bits of their fields, and we need to handle

    // wraparounds to avoid our power tracks stopping after a few hours.

    constexpr uint32_t highestBit = 1 << 31;

    if ((mSample & highestBit) && !(aSample & highestBit)) {

      mIsSampleNew = true;

      ++mWrapAroundCount;

      mSample = aSample;

    } else {

      NS_WARNING("unexpected sample with smaller value");

    }

  }



 private:

  double mSample;

  uint32_t mSample;

  uint32_t mEnergyStatusUnits;

  uint32_t mWrapAroundCount;

  bool mIsSampleNew;

};
@@ -203,8 +230,8 @@ class RAPL { 
  // This field records whether the quirk is present.

  bool mHasRamUnitsQuirk;



  // The abovementioned 15.3 microJoules value.

  static constexpr double kQuirkyRamJoulesPerTick = (double)1 / 65536;

  // The abovementioned 15.3 microJoules value. (2^16 = 65536)

  static constexpr double kQuirkyRamEnergyStatusUnits = 16;



  // The struct passed to diagCall64().

  pkg_energy_statistics_t* mPkes;
@@ -331,10 +358,6 @@ class RAPL { 
    delete mRam;

  }



  static double Joules(uint64_t aTicks, double aJoulesPerTick) {

    return double(aTicks) * aJoulesPerTick;

  }



  void Sample() {

    constexpr uint64_t kSupportedVersion = 1;
@@ -365,17 +388,15 @@ class RAPL { 
    // Bits 12:8 are the ESU.

    // Energy measurements come in multiples of 1/(2^ESU).

    uint32_t energyStatusUnits = (mPkes->pkg_power_unit >> 8) & 0x1f;

    double joulesPerTick = ((double)1 / (1 << energyStatusUnits));



    mPkg->AddSample(Joules(mPkes->pkg_energy, joulesPerTick));

    mCores->AddSample(Joules(mPkes->pp0_energy, joulesPerTick));

    mPkg->AddSample(mPkes->pkg_energy, energyStatusUnits);

    mCores->AddSample(mPkes->pp0_energy, energyStatusUnits);

    if (mIsGpuSupported) {

      mGpu->AddSample(Joules(mPkes->pp1_energy, joulesPerTick));

      mGpu->AddSample(mPkes->pp1_energy, energyStatusUnits);

    }

    if (mIsRamSupported) {

      mRam->AddSample(Joules(mPkes->ddr_energy, mHasRamUnitsQuirk

                                                    ? kQuirkyRamJoulesPerTick

                                                    : joulesPerTick));

      mRam->AddSample(mPkes->ddr_energy, mHasRamUnitsQuirk

                                             ? kQuirkyRamEnergyStatusUnits

                                             : energyStatusUnits);

    }

  }

};