DiskUtilizationTracker.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#ifndef TRACK_DISK_UTILIZATION
#define TRACK_DISK_UTILIZATION 0
#endif
 
#include "CoreTypes.h"
 
#if TRACK_DISK_UTILIZATION
#include "HAL/PlatformMisc.h"
#include "HAL/ThreadSafeBool.h"
#include "ProfilingDebugging/CsvProfiler.h"
 
CSV_DECLARE_CATEGORY_EXTERN(DiskIO);
 
#ifndef SPEW_DISK_UTILIZATION
#define SPEW_DISK_UTILIZATION 0
#endif // SPEW_DISK_UTILIZATION
 
struct FDiskUtilizationTracker
{
    struct UtilizationStats
    {
        UtilizationStats() :
            TotalReads(0),
            TotalSeeks(0),
            TotalBytesRead(0),
            TotalSeekDistance(0),
            TotalIOTime(0.0),
            TotalIdleTime(0.0)
        {}
 
        double GetOverallThroughputBS() const
        {
            return (TotalIOTime + TotalIdleTime) > 0.0 ? double(TotalBytesRead) / (TotalIOTime + TotalIdleTime) : 0.0;
        }
 
        double GetOverallThroughputMBS() const
        {
            return GetOverallThroughputBS() / (1024.0 * 1024.0);
        }
 
        double GetReadThrougputBS() const
        {
            return TotalIOTime > 0.0 ? double(TotalBytesRead) / TotalIOTime : 0.0;
        }
 
        double GetReadThrougputMBS() const
        {
            return GetReadThrougputBS() / (1024.0 * 1024.0);
        }
 
        double GetTotalIdleTimeInSeconds() const
        {
            return TotalIdleTime;
        }
 
        double GetTotalIOTimeInSeconds() const
        {
            return TotalIOTime;
        }
 
        double GetPercentTimeIdle() const
        {
            double TotalTime = TotalIOTime + TotalIdleTime;
 
            return TotalTime > 0.0 ? (100.0f * TotalIdleTime) / TotalTime : 0.0;
        }
 
        void Reset()
        {
            TotalReads = 0;
            TotalSeeks = 0;
            TotalBytesRead = 0;
            TotalSeekDistance = 0;
            TotalIOTime = 0.0;
            TotalIdleTime = 0.0;
        }
 
        void Dump() const;
 
        uint64 TotalReads;
        uint64 TotalSeeks;
 
        uint64 TotalBytesRead;
        uint64 TotalSeekDistance;
 
        double TotalIOTime;
        double TotalIdleTime;
    };
 
    UtilizationStats LongTermStats;
    UtilizationStats ShortTermStats;
 
    FCriticalSection CriticalSection;
 
    uint64 IdleStartCycle;
    uint64 ReadStartCycle;
 
    uint64 InFlightBytes;
    int32  InFlightReads;
 
    FThreadSafeBool bResetShortTermStats;
 
    FDiskUtilizationTracker() :
        IdleStartCycle(0),
        ReadStartCycle(0),
        InFlightBytes(0),
        InFlightReads(0)
    {
    }
 
    void StartRead(uint64 InReadBytes, uint64 InSeekDistance = 0);
    void FinishRead();
 
    uint32 GetOutstandingRequests() const
    {
        return InFlightReads;
    }
 
    const struct UtilizationStats& GetLongTermStats() const
    {
        return LongTermStats;
    }
 
    const struct UtilizationStats& GetShortTermStats() const
    {
        return ShortTermStats;
    }
 
    void ResetShortTermStats()
    {
        bResetShortTermStats = true;
    }
 
private:
    static float GetThrottleRateMBS();
    static constexpr float PrintFrequencySeconds = 0.5f;
 
    void MaybePrint();
};
 
extern FDiskUtilizationTracker GDiskUtilizationTracker;
 
struct FScopedDiskUtilizationTracker
{
    FScopedDiskUtilizationTracker(uint64 InReadBytes, uint64 InSeekDistance) 
    {
        GDiskUtilizationTracker.StartRead(InReadBytes, InSeekDistance);
    }
 
    ~FScopedDiskUtilizationTracker()
    {
        GDiskUtilizationTracker.FinishRead();
    }
};
 
#else
 
struct FScopedDiskUtilizationTracker
{
    FScopedDiskUtilizationTracker(uint64 Size, uint64 SeekDistance)
    {
    }
};
 
#endif // TRACK_DISK_UTILIZATION