DeviceManager Class Reference

orchestrate platforms (programming models) and set up the default device on each platform More...

Collaboration diagram for DeviceManager:

Public Member Functions
	DeviceManager (int local_rank, int local_size)
	constructor More...
	~DeviceManager ()
int	getDefaultDeviceNum () const
int	getNumDevices () const

Static Public Member Functions
static void	initializeGlobalDeviceManager (int local_rank, int local_size)
	initialize the global instance of DeviceManager arguments are the same as the constructor More...
static const DeviceManager &	getGlobal ()
	global instance accessor More...

Private Attributes
int	default_device_num
	the id of default device. Must be defined before platform device manager objects More...
int	num_devices
	the number of devices. Must be defined before platform device manager objects More...

Static Private Attributes
static std::unique_ptr< DeviceManager >	global
	the global singleton which can be used to query default devices and all the captured devices. More...

Detailed Description

orchestrate platforms (programming models) and set up the default device on each platform

Currently support CUDA, OpenMP, SYCL

Each platform provides its own device manager class. Each individual device manager initializes all the devices visible to the process and also set the default device. The first initialized platform selects the default device for the current process and all the rest platforms follow that choice.

The device manager on each platform may be constomized to store a list of known device numbers or a list of context device handles depending on the need.

DeviceManager assumes there is only one type of accelerators although they may support multiple platforms. Under this assumption, the numbers of devices captured on all the platforms must agree.

DeviceManager::global is intended to the per-process global instance and should be initialized after MPI initialization in main().

Definition at line 50 of file DeviceManager.h.

Constructor & Destructor Documentation

DeviceManager()

DeviceManager	(	int	local_rank,
		int	local_size
	)

constructor

Parameters

local_rank	the rank id of the node local MPI communicator
local_size	the size of the node local MPI communicator

Definition at line 22 of file DeviceManager.cpp.

References qmcplusplus::app_warning(), and DeviceManager::num_devices.

    : default_device_num(-1),
      num_devices(0)
#if defined(ENABLE_CUDA)
      , cuda_dm_(default_device_num, num_devices, local_rank, local_size)
#endif
#if defined(ENABLE_OFFLOAD)
      , omptarget_dm_(default_device_num, num_devices, local_rank, local_size)
#endif
#if defined(ENABLE_SYCL)
      , sycl_dm_(default_device_num, num_devices, local_rank, local_size)
#endif
{
  if (num_devices > 0)
  {
    if (local_size % num_devices != 0)
      app_warning() << "The number of MPI ranks on the node is not divisible by the number of accelerators. "
                    << "Imbalanced load may cause performance loss.\n";
  }
}

~DeviceManager()

~DeviceManager ( )

default

Member Function Documentation

getDefaultDeviceNum()

int getDefaultDeviceNum ( ) const

inline

Definition at line 62 of file DeviceManager.h.

References DeviceManager::default_device_num.

{ return default_device_num; }

getGlobal()

const DeviceManager & getGlobal ( )

static

global instance accessor

Definition at line 57 of file DeviceManager.cpp.

References DeviceManager::global.

Referenced by QMCMain::QMCMain().

{
  if (!global)
    throw std::runtime_error("DeviceManager::getGlobal the global instance was not initialized.");
  return *global;
}

getNumDevices()

int getNumDevices ( ) const

inline

Definition at line 63 of file DeviceManager.h.

References DeviceManager::num_devices.

Referenced by QMCMain::QMCMain().

{ return num_devices; }

initializeGlobalDeviceManager()

void initializeGlobalDeviceManager ( int  local_rank, int  local_size  )

static

initialize the global instance of DeviceManager arguments are the same as the constructor

Definition at line 47 of file DeviceManager.cpp.

References DeviceManager::global.

Referenced by main(), and QMCMain::QMCMain().

{
  // throw error on subsequent calls to initializeGlobalDeviceManager
  // if the desired behavior is no-op. std::call_once can be used.
  if (global)
    throw std::runtime_error(
        "DeviceManager::initializeGlobalDeviceManager the global instance cannot be initialized again.");
  global = std::make_unique<DeviceManager>(local_rank, local_size);
}

Member Data Documentation

default_device_num

int default_device_num

private

the id of default device. Must be defined before platform device manager objects

Definition at line 86 of file DeviceManager.h.

Referenced by DeviceManager::getDefaultDeviceNum().

global

std::unique_ptr< DeviceManager > global

staticprivate

the global singleton which can be used to query default devices and all the captured devices.

Definition at line 84 of file DeviceManager.h.

Referenced by DeviceManager::getGlobal(), and DeviceManager::initializeGlobalDeviceManager().

num_devices

int num_devices

private

the number of devices. Must be defined before platform device manager objects

Definition at line 88 of file DeviceManager.h.

Referenced by DeviceManager::DeviceManager(), and DeviceManager::getNumDevices().

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The documentation for this class was generated from the following files:

• /home/pk7/projects/qmc/for_cron_doxygen/qmcpack/src/Platforms/DeviceManager.h
• /home/pk7/projects/qmc/for_cron_doxygen/qmcpack/src/Platforms/DeviceManager.cpp