Class DriverAPINativeMethods.ContextManagement

Combines all API calls for context management

Inheritance

System.Object

DriverAPINativeMethods.ContextManagement

Inherited Members

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Namespace: ManagedCuda

Assembly: ManagedCuda.dll

Syntax

public static class ContextManagement

Methods

cuCtxAttach(ref CUcontext, CUCtxAttachFlags)

Increments the usage count of the context and passes back a context handle in pctx that must be passed to cuCtxDetach(CUcontext) when the application is done with the context. cuCtxAttach(ref CUcontext, CUCtxAttachFlags) fails if there is no context current to the thread. Currently, the flags parameter must be None.

Declaration

[Obsolete("Don't use this CUDA API call with CUDA version >= 4.0.")]
public static CUResult cuCtxAttach(ref CUcontext pctx, CUCtxAttachFlags flags)

Parameters

Type	Name	Description
CUcontext	pctx	Returned context handle of the current context
CUCtxAttachFlags	flags	Context attach flags (must be None)

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxCreate_v2(ref CUcontext, CUCtxFlags, CUdevice)

Creates a new CUDA context and associates it with the calling thread. The flags parameter is described in CUCtxFlags. The context is created with a usage count of 1 and the caller of cuCtxCreate_v2(ref CUcontext, CUCtxFlags, CUdevice) must call cuCtxDestroy(CUcontext) or cuCtxDetach(CUcontext) when done using the context. If a context is already current to the thread, it is supplanted by the newly created context and may be restored by a subsequent call to cuCtxPopCurrent(ref CUcontext).

Declaration

public static CUResult cuCtxCreate_v2(ref CUcontext pctx, CUCtxFlags flags, CUdevice dev)

Parameters

Type	Name	Description
CUcontext	pctx	Returned context handle of the new context
CUCtxFlags	flags	Context creation flags. See CUCtxFlags
CUdevice	dev	Device to create context on

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue, ErrorInvalidDevice, ErrorOutOfMemory, ErrorUnknown. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxDestroy(CUcontext)

Destroys the CUDA context specified by ctx. If the context usage count is not equal to 1, or the context is current to any CPU thread other than the current one, this function fails. Floating contexts (detached from a CPU thread via cuCtxPopCurrent(ref CUcontext)) may be destroyed by this function.

Declaration

[Obsolete("Don't use this CUDA API call with CUDA version >= 4.0.")]
public static CUResult cuCtxDestroy(CUcontext ctx)

Parameters

Type	Name	Description
CUcontext	ctx	Context to destroy

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxDestroy_v2(CUcontext)

Destroys the CUDA context specified by ctx. The context ctx will be destroyed regardless of how many threads it is current to. It is the responsibility of the calling function to ensure that no API call is issued to ctx while cuCtxDestroy_v2() is executing. If ctx is current to the calling thread then ctx will also be popped from the current thread's context stack (as though cuCtxPopCurrent() were called). If ctx is current to other threads, then ctx will remain current to those threads, and attempting to access ctx from those threads will result in the error ErrorContextIsDestroyed.

Declaration

public static CUResult cuCtxDestroy_v2(CUcontext ctx)

Parameters

Type	Name	Description
CUcontext	ctx	Context to destroy

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue, ErrorContextIsDestroyed. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxDetach(CUcontext)

Decrements the usage count of the context ctx, and destroys the context if the usage count goes to 0. The context must be a handle that was passed back by cuCtxCreate_v2(ref CUcontext, CUCtxFlags, CUdevice) or cuCtxAttach(ref CUcontext, CUCtxAttachFlags), and must be current to the calling thread.

Declaration

[Obsolete("Don't use this CUDA API call with CUDA version >= 4.0.")]
public static CUResult cuCtxDetach(CUcontext ctx)

Parameters

Type	Name	Description
CUcontext	ctx	Context to destroy

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxGetApiVersion(CUcontext, ref UInt32)

Returns the API version used to create ctx in version. If ctx is NULL, returns the API version used to create the currently bound context.

This wil return the API version used to create a context (for example, 3010 or 3020), which library developers can use to direct callers to a specific API version. Note that this API version may not be the same as returned by cuDriverGetVersion(ref Int32).

Declaration

public static CUResult cuCtxGetApiVersion(CUcontext ctx, ref uint version)

Parameters

Type	Name	Description
CUcontext	ctx
System.UInt32	version

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorUnknown. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxGetCacheConfig(ref CUFuncCache)

On devices where the L1 cache and shared memory use the same hardware resources, this function returns through pconfig the preferred cache configuration for the current context. This is only a preference. The driver will use the requested configuration if possible, but it is free to choose a different configuration if required to execute functions.

This will return a pconfig of PreferNone on devices where the size of the L1 cache and shared memory are fixed.

Declaration

public static CUResult cuCtxGetCacheConfig(ref CUFuncCache pconfig)

Parameters

Type	Name	Description
CUFuncCache	pconfig

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxGetCurrent(ref CUcontext)

Returns in ctx the CUDA context bound to the calling CPU thread. If no context is bound to the calling CPU thread then ctx is set to NULL and Success is returned.

Declaration

public static CUResult cuCtxGetCurrent(ref CUcontext pctx)

Parameters

Type	Name	Description
CUcontext	pctx	Returned context handle

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxGetDevice(ref CUdevice)

Returns in device the ordinal of the current context’s device.

Declaration

public static CUResult cuCtxGetDevice(ref CUdevice device)

Parameters

Type	Name	Description
CUdevice	device	Returned device ID for the current context

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxGetFlags(ref CUCtxFlags)

Returns the flags for the current context

Returns in \p *flags the flags of the current context. See ::cuCtxCreate for flag values.

Declaration

public static CUResult cuCtxGetFlags(ref CUCtxFlags flags)

Parameters

Type	Name	Description
CUCtxFlags	flags	Pointer to store flags of current context

Returns

Type	Description
CUResult

cuCtxGetSharedMemConfig(ref CUsharedconfig)

Returns the current shared memory configuration for the current context.

This function will return in \p pConfig the current size of shared memory banks in the current context. On devices with configurable shared memory banks, cuCtxSetSharedMemConfig(CUsharedconfig) can be used to change this setting, so that all subsequent kernel launches will by default use the new bank size. When cuCtxGetSharedMemConfig(ref CUsharedconfig) is called on devices without configurable shared memory, it will return the fixed bank size of the hardware.

The returned bank configurations can be either: - FourByteBankSize: set shared memory bank width to be natively four bytes. - EightByteBankSize: set shared memory bank width to be natively eight bytes.

Declaration

public static CUResult cuCtxGetSharedMemConfig(ref CUsharedconfig pConfig)

Parameters

Type	Name	Description
CUsharedconfig	pConfig	returned shared memory configuration

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue.

cuCtxGetStreamPriorityRange(ref Int32, ref Int32)

Returns numerical values that correspond to the least and greatest stream priorities.

Returns in leastPriority and greatestPriority the numerical values that correspond to the least and greatest stream priorities respectively. Stream priorities follow a convention where lower numbers imply greater priorities. The range of meaningful stream priorities is given by [greatestPriority, leastPriority]. If the user attempts to create a stream with a priority value that is outside the meaningful range as specified by this API, the priority is automatically clamped down or up to either leastPriority or greatestPriority respectively. See ::cuStreamCreateWithPriority for details on creating a priority stream. A NULL may be passed in for leastPriority or greatestPriority if the value is not desired. This function will return '0' in both leastPriority and greatestPriority if the current context's device does not support stream priorities (see ::cuDeviceGetAttribute).

Declaration

public static CUResult cuCtxGetStreamPriorityRange(ref int leastPriority, ref int greatestPriority)

Parameters

Type	Name	Description
System.Int32	leastPriority	Pointer to an int in which the numerical value for least stream priority is returned
System.Int32	greatestPriority	Pointer to an int in which the numerical value for greatest stream priority is returned

Returns

Type	Description
CUResult

cuCtxPopCurrent(ref CUcontext)

Pops the current CUDA context from the CPU thread. The CUDA context must have a usage count of 1. CUDA contexts have a usage count of 1 upon creation; the usage count may be incremented with cuCtxAttach(ref CUcontext, CUCtxAttachFlags) and decremented with cuCtxDetach(CUcontext).

If successful, cuCtxPopCurrent(ref CUcontext) passes back the old context handle in pctx. That context may then be made current to a different CPU thread by calling cuCtxPushCurrent(CUcontext).

Floating contexts may be destroyed by calling cuCtxDestroy(CUcontext).

If a context was current to the CPU thread before cuCtxCreate_v2(ref CUcontext, CUCtxFlags, CUdevice) or cuCtxPushCurrent(CUcontext) was called, this function makes that context current to the CPU thread again.

Declaration

[Obsolete("Don't use this CUDA API call with CUDA version >= 4.0.")]
public static CUResult cuCtxPopCurrent(ref CUcontext pctx)

Parameters

Type	Name	Description
CUcontext	pctx	Returned new context handle

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxPopCurrent_v2(ref CUcontext)

Pops the current CUDA context from the CPU thread. The CUDA context must have a usage count of 1. CUDA contexts have a usage count of 1 upon creation; the usage count may be incremented with cuCtxAttach(ref CUcontext, CUCtxAttachFlags) and decremented with cuCtxDetach(CUcontext).

If successful, cuCtxPopCurrent(ref CUcontext) passes back the old context handle in pctx. That context may then be made current to a different CPU thread by calling cuCtxPushCurrent(CUcontext).

Floating contexts may be destroyed by calling cuCtxDestroy(CUcontext).

If a context was current to the CPU thread before cuCtxCreate_v2(ref CUcontext, CUCtxFlags, CUdevice) or cuCtxPushCurrent(CUcontext) was called, this function makes that context current to the CPU thread again.

Declaration

public static CUResult cuCtxPopCurrent_v2(ref CUcontext pctx)

Parameters

Type	Name	Description
CUcontext	pctx	Returned new context handle

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxPushCurrent(CUcontext)

Pushes the given context ctx onto the CPU thread’s stack of current contexts. The specified context becomes the CPU thread’s current context, so all CUDA functions that operate on the current context are affected.

The previous current context may be made current again by calling cuCtxDestroy(CUcontext) or cuCtxPopCurrent(ref CUcontext).

The context must be "floating," i.e. not attached to any thread. Contexts are made to float by calling cuCtxPopCurrent(ref CUcontext).

Declaration

[Obsolete("Don't use this CUDA API call with CUDA version >= 4.0.")]
public static CUResult cuCtxPushCurrent(CUcontext ctx)

Parameters

Type	Name	Description
CUcontext	ctx	Floating context to attach

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxPushCurrent_v2(CUcontext)

Pushes the given context ctx onto the CPU thread’s stack of current contexts. The specified context becomes the CPU thread’s current context, so all CUDA functions that operate on the current context are affected.

The previous current context may be made current again by calling cuCtxDestroy(CUcontext) or cuCtxPopCurrent(ref CUcontext).

The context must be "floating," i.e. not attached to any thread. Contexts are made to float by calling cuCtxPopCurrent(ref CUcontext).

Declaration

public static CUResult cuCtxPushCurrent_v2(CUcontext ctx)

Parameters

Type	Name	Description
CUcontext	ctx	Floating context to attach

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxSetCacheConfig(CUFuncCache)

On devices where the L1 cache and shared memory use the same hardware resources, this sets through config the preferred cache configuration for the current context. This is only a preference. The driver will use the requested configuration if possible, but it is free to choose a different configuration if required to execute the function. Any function preference set via cuFuncSetCacheConfig(CUfunction, CUFuncCache) will be preferred over this context-wide setting. Setting the context-wide cache configuration to PreferNone will cause subsequent kernel launches to prefer to not change the cache configuration unless required to launch the kernel.

This setting does nothing on devices where the size of the L1 cache and shared memory are fixed.

Launching a kernel with a different preference than the most recent preference setting may insert a device-side synchronization point.

Declaration

public static CUResult cuCtxSetCacheConfig(CUFuncCache config)

Parameters

Type	Name	Description
CUFuncCache	config

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxSetCurrent(CUcontext)

Binds the specified CUDA context to the calling CPU thread. If ctx is NULL then the CUDA context previously bound to the calling CPU thread is unbound and Success is returned.

If there exists a CUDA context stack on the calling CPU thread, this will replace the top of that stack with ctx. If ctx is NULL then this will be equivalent to popping the top of the calling CPU thread's CUDA context stack (or a no-op if the calling CPU thread's CUDA context stack is empty).

Declaration

public static CUResult cuCtxSetCurrent(CUcontext ctx)

Parameters

Type	Name	Description
CUcontext	ctx	Context to bind to the calling CPU thread

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext. Note that this function may also return error codes from previous, asynchronous launches.

cuCtxSetSharedMemConfig(CUsharedconfig)

Sets the shared memory configuration for the current context.

On devices with configurable shared memory banks, this function will set the context's shared memory bank size which is used for subsequent kernel launches.

Changed the shared memory configuration between launches may insert a device side synchronization point between those launches.

Changing the shared memory bank size will not increase shared memory usage or affect occupancy of kernels, but may have major effects on performance. Larger bank sizes will allow for greater potential bandwidth to shared memory, but will change what kinds of accesses to shared memory will result in bank conflicts.

This function will do nothing on devices with fixed shared memory bank size.

The supported bank configurations are: - DefaultBankSize: set bank width to the default initial setting (currently, four bytes). - FourByteBankSize: set shared memory bank width to be natively four bytes. - EightByteBankSize: set shared memory bank width to be natively eight bytes.

Declaration

public static CUResult cuCtxSetSharedMemConfig(CUsharedconfig config)

Parameters

Type	Name	Description
CUsharedconfig	config	requested shared memory configuration

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext, ErrorInvalidValue.

cuCtxSynchronize()

Blocks until the device has completed all preceding requested tasks. cuCtxSynchronize() returns an error if one of the preceding tasks failed. If the context was created with the BlockingSync flag, the CPU thread will block until the GPU context has finished its work.

Declaration

public static CUResult cuCtxSynchronize()

Returns

Type	Description
CUResult	CUDA Error Codes: Success, ErrorDeinitialized, ErrorNotInitialized, ErrorInvalidContext. Note that this function may also return error codes from previous, asynchronous launches.

cuDevicePrimaryCtxGetState(CUdevice, ref CUCtxFlags, ref Int32)

Get the state of the primary context

Returns in \p *flags the flags for the primary context of \p dev, and in \p *active whether it is active. See ::cuDevicePrimaryCtxSetFlags for flag values.

Declaration

public static CUResult cuDevicePrimaryCtxGetState(CUdevice dev, ref CUCtxFlags flags, ref int active)

Parameters

Type	Name	Description
CUdevice	dev	Device to get primary context flags for
CUCtxFlags	flags	Pointer to store flags
System.Int32	active	Pointer to store context state; 0 = inactive, 1 = active

Returns

Type	Description
CUResult

cuDevicePrimaryCtxRelease(CUdevice)

Release the primary context on the GPU

Releases the primary context interop on the device by decreasing the usage count by 1. If the usage drops to 0 the primary context of device \p dev will be destroyed regardless of how many threads it is current to.

Please note that unlike ::cuCtxDestroy() this method does not pop the context from stack in any circumstances.

Declaration

public static CUResult cuDevicePrimaryCtxRelease(CUdevice dev)

Parameters

Type	Name	Description
CUdevice	dev	Device which primary context is released

Returns

Type	Description
CUResult

cuDevicePrimaryCtxReset(CUdevice)

Destroy all allocations and reset all state on the primary context

Explicitly destroys and cleans up all resources associated with the current device in the current process.

Note that it is responsibility of the calling function to ensure that no other module in the process is using the device any more. For that reason it is recommended to use ::cuDevicePrimaryCtxRelease() in most cases. However it is safe for other modules to call ::cuDevicePrimaryCtxRelease() even after resetting the device.

Declaration

public static CUResult cuDevicePrimaryCtxReset(CUdevice dev)

Parameters

Type	Name	Description
CUdevice	dev	Device for which primary context is destroyed

Returns

Type	Description
CUResult

cuDevicePrimaryCtxRetain(ref CUcontext, CUdevice)

Retain the primary context on the GPU.

Retains the primary context on the device, creating it if necessary, increasing its usage count. The caller must call ::cuDevicePrimaryCtxRelease() when done using the context. Unlike ::cuCtxCreate() the newly created context is not pushed onto the stack.

Context creation will fail with ::CUDA_ERROR_UNKNOWN if the compute mode of the device is ::CU_COMPUTEMODE_PROHIBITED. Similarly, context creation will also fail with ::CUDA_ERROR_UNKNOWN if the compute mode for the device is set to ::CU_COMPUTEMODE_EXCLUSIVE and there is already an active, non-primary, context on the device. The function ::cuDeviceGetAttribute() can be used with ::CU_DEVICE_ATTRIBUTE_COMPUTE_MODE to determine the compute mode of the device. The nvidia-smi tool can be used to set the compute mode for devices. Documentation for nvidia-smi can be obtained by passing a -h option to it.

Please note that the primary context always supports pinned allocations. Other flags can be specified by ::cuDevicePrimaryCtxSetFlags().

Declaration

public static CUResult cuDevicePrimaryCtxRetain(ref CUcontext pctx, CUdevice dev)

Parameters

Type	Name	Description
CUcontext	pctx	Returned context handle of the new context
CUdevice	dev	Device for which primary context is requested

Returns

Type	Description
CUResult

cuDevicePrimaryCtxSetFlags(CUdevice, CUCtxFlags)

Set flags for the primary context

Sets the flags for the primary context on the device overwriting perviously set ones. If the primary context is already created ::CUDA_ERROR_PRIMARY_CONTEXT_ACTIVE is returned.

The three LSBs of the \p flags parameter can be used to control how the OS thread, which owns the CUDA context at the time of an API call, interacts with the OS scheduler when waiting for results from the GPU. Only one of the scheduling flags can be set when creating a context.

Declaration

public static CUResult cuDevicePrimaryCtxSetFlags(CUdevice dev, CUCtxFlags flags)

Parameters

Type	Name	Description
CUdevice	dev	Device for which the primary context flags are set
CUCtxFlags	flags	New flags for the device

Returns

Type	Description
CUResult