src/gromacs/gpu_utils/gpuregiontimer.h

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  35
  36 /*! \libinternal \file
  37  *  \brief Defines the GPU region timer implementation/wrapper classes.
  38  *  The implementations live in gpuregiontimer.cuh for CUDA and gpuregiontimer_ocl.h for OpenCL.
  39  *
  40  *  \author Aleksei Iupinov <a.yupinov@gmail.com>
  41  */
  42
  43 #ifndef GMX_GPU_UTILS_GPUREGIONTIMER_H
  44 #define GMX_GPU_UTILS_GPUREGIONTIMER_H
  45
  46 #include <string>
  47
  48 #include "gromacs/utility/gmxassert.h"
  49
  50 //! Debug GPU timers in debug builds only
  51 #if defined(NDEBUG)
  52 static const bool c_debugTimerState = false;
  53 #else
  54 static const bool c_debugTimerState = true;
  55 #endif
  56
  57 /*! \libinternal \brief
  58  * This is a GPU region timing wrapper class.
  59  * It allows for host-side tracking of the accumulated execution timespans in GPU code
  60  * (measuring kernel or transfers duration).
  61  * It also partially tracks the correctness of the timer state transitions,
  62  * as far as current implementation allows (see TODO in getLastRangeTime() for a disabled check).
  63  * Internally it uses GpuRegionTimerImpl for measuring regions.
  64  */
  65 template<typename GpuRegionTimerImpl>
  66 class GpuRegionTimerWrapper
  67 {
  68     //! The timer state used for debug-only assertions
  69     enum class TimerState
  70     {
  71         Idle,
  72         Recording,
  73         Stopped
  74     } debugState_ = TimerState::Idle;
  75
  76     //! The number of times the timespan has been measured
  77     unsigned int callCount_ = 0;
  78     //! The accumulated duration of the timespans measured (milliseconds)
  79     double totalMilliseconds_ = 0.0;
  80     //! The underlying region timer implementation
  81     GpuRegionTimerImpl impl_;
  82
  83 public:
  84     /*! \brief
  85      * To be called before the region start.
  86      *
  87      * \param[in] deviceStream   The GPU command stream where the event being measured takes place.
  88      */
  89     void openTimingRegion(const DeviceStream& deviceStream)
  90     {
  91         if (c_debugTimerState)
  92         {
  93             std::string error = "GPU timer should be idle, but is "
  94                                 + std::string((debugState_ == TimerState::Stopped) ? "stopped" : "recording")
  95                                 + ".";
  96             GMX_ASSERT(debugState_ == TimerState::Idle, error.c_str());
  97             debugState_ = TimerState::Recording;
  98         }
  99         impl_.openTimingRegion(deviceStream);
 100     }
 101     /*! \brief
 102      * To be called after the region end.
 103      *
 104      * \param[in] deviceStream   The GPU command stream where the event being measured takes place.
 105      */
 106     void closeTimingRegion(const DeviceStream& deviceStream)
 107     {
 108         if (c_debugTimerState)
 109         {
 110             std::string error = "GPU timer should be recording, but is "
 111                                 + std::string((debugState_ == TimerState::Idle) ? "idle" : "stopped")
 112                                 + ".";
 113             GMX_ASSERT(debugState_ == TimerState::Recording, error.c_str());
 114             debugState_ = TimerState::Stopped;
 115         }
 116         callCount_++;
 117         impl_.closeTimingRegion(deviceStream);
 118     }
 119     /*! \brief
 120      * Accumulates the last timespan of all the events used into the total duration,
 121      * and resets the internal timer state.
 122      * To be called after closeTimingRegion() and the command stream of the event having been
 123      * synchronized. \returns The last timespan (in milliseconds).
 124      */
 125     double getLastRangeTime()
 126     {
 127         if (c_debugTimerState)
 128         {
 129             /* The assertion below is commented because it is currently triggered on a special case:
 130              * the early return before the local non-bonded kernel launch if there is nothing to do.
 131              * This can be reproduced in OpenCL build by running
 132              * mdrun-mpi-test -ntmpi 2 --gtest_filter=*Empty*
 133              * Similarly, the GpuRegionTimerImpl suffers from non-nullptr
 134              * cl_event conditionals which ideally should only be asserts.
 135              * TODO: improve internal task scheduling, re-enable the assert, turn conditionals into asserts
 136              */
 137             /*
 138                std::string error = "GPU timer should be stopped, but is " + std::string((debugState_ == TimerState::Idle) ? "idle" : "recording") + ".";
 139                GMX_ASSERT(debugState_ == TimerState::Stopped, error.c_str());
 140              */
 141             debugState_ = TimerState::Idle;
 142         }
 143         double milliseconds = impl_.getLastRangeTime();
 144         totalMilliseconds_ += milliseconds;
 145         return milliseconds;
 146     }
 147     /*! \brief Resets the implementation and total time/call count to zeroes. */
 148     void reset()
 149     {
 150         if (c_debugTimerState)
 151         {
 152             debugState_ = TimerState::Idle;
 153         }
 154         totalMilliseconds_ = 0.0;
 155         callCount_         = 0;
 156         impl_.reset();
 157     }
 158     /*! \brief Gets total time recorded (in milliseconds). */
 159     double getTotalTime() const { return totalMilliseconds_; }
 160     /*! \brief Gets total call count recorded. */
 161     unsigned int getCallCount() const { return callCount_; }
 162     /*! \brief
 163      * Gets a pointer to a new timing event for passing into individual GPU API calls
 164      * within the region if they require it (e.g. on OpenCL).
 165      * \returns The pointer to the underlying single command timing event.
 166      */
 167     CommandEvent* fetchNextEvent()
 168     {
 169         if (c_debugTimerState)
 170         {
 171             std::string error = "GPU timer should be recording, but is "
 172                                 + std::string((debugState_ == TimerState::Idle) ? "idle" : "stopped")
 173                                 + ".";
 174             GMX_ASSERT(debugState_ == TimerState::Recording, error.c_str());
 175         }
 176         return impl_.fetchNextEvent();
 177     }
 178 };
 179
 180 #endif