Provided by: nvidia-cuda-dev_9.1.85-3ubuntu1_amd64 
NAME
Event Management -
Functions
CUresult cuEventCreate (CUevent *phEvent, unsigned int Flags)
Creates an event.
CUresult cuEventDestroy (CUevent hEvent)
Destroys an event.
CUresult cuEventElapsedTime (float *pMilliseconds, CUevent hStart, CUevent hEnd)
Computes the elapsed time between two events.
CUresult cuEventQuery (CUevent hEvent)
Queries an event's status.
CUresult cuEventRecord (CUevent hEvent, CUstream hStream)
Records an event.
CUresult cuEventSynchronize (CUevent hEvent)
Waits for an event to complete.
CUresult cuStreamBatchMemOp (CUstream stream, unsigned int count, CUstreamBatchMemOpParams *paramArray,
unsigned int flags)
Batch operations to synchronize the stream via memory operations.
CUresult cuStreamWaitValue32 (CUstream stream, CUdeviceptr addr, cuuint32_t value, unsigned int flags)
Wait on a memory location.
CUresult cuStreamWaitValue64 (CUstream stream, CUdeviceptr addr, cuuint64_t value, unsigned int flags)
Wait on a memory location.
CUresult cuStreamWriteValue32 (CUstream stream, CUdeviceptr addr, cuuint32_t value, unsigned int flags)
Write a value to memory.
CUresult cuStreamWriteValue64 (CUstream stream, CUdeviceptr addr, cuuint64_t value, unsigned int flags)
Write a value to memory.
Detailed Description
\brief event management functions of the low-level CUDA driver API (cuda.h)
This section describes the event management functions of the low-level CUDA driver application
programming interface.
Function Documentation
CUresult cuEventCreate (CUevent * phEvent, unsigned int Flags)
Creates an event *phEvent for the current context with the flags specified via Flags. Valid flags
include:
• CU_EVENT_DEFAULT: Default event creation flag.
• CU_EVENT_BLOCKING_SYNC: Specifies that the created event should use blocking synchronization. A CPU
thread that uses cuEventSynchronize() to wait on an event created with this flag will block until the
event has actually been recorded.
• CU_EVENT_DISABLE_TIMING: Specifies that the created event does not need to record timing data. Events
created with this flag specified and the CU_EVENT_BLOCKING_SYNC flag not specified will provide the
best performance when used with cuStreamWaitEvent() and cuEventQuery().
• CU_EVENT_INTERPROCESS: Specifies that the created event may be used as an interprocess event by
cuIpcGetEventHandle(). CU_EVENT_INTERPROCESS must be specified along with CU_EVENT_DISABLE_TIMING.
Parameters:
phEvent - Returns newly created event
Flags - Event creation flags
Returns:
CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT,
CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_OUT_OF_MEMORY
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuEventRecord, cuEventQuery, cuEventSynchronize, cuEventDestroy, cuEventElapsedTime, cudaEventCreate,
cudaEventCreateWithFlags
CUresult cuEventDestroy (CUevent hEvent)
Destroys the event specified by hEvent.
An event may be destroyed before it is complete (i.e., while cuEventQuery() would return
CUDA_ERROR_NOT_READY). In this case, the call does not block on completion of the event, and any
associated resources will automatically be released asynchronously at completion.
Parameters:
hEvent - Event to destroy
Returns:
CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT,
CUDA_ERROR_INVALID_HANDLE
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuEventCreate, cuEventRecord, cuEventQuery, cuEventSynchronize, cuEventElapsedTime, cudaEventDestroy
CUresult cuEventElapsedTime (float * pMilliseconds, CUevent hStart, CUevent hEnd)
Computes the elapsed time between two events (in milliseconds with a resolution of around 0.5
microseconds).
If either event was last recorded in a non-NULL stream, the resulting time may be greater than expected
(even if both used the same stream handle). This happens because the cuEventRecord() operation takes
place asynchronously and there is no guarantee that the measured latency is actually just between the two
events. Any number of other different stream operations could execute in between the two measured events,
thus altering the timing in a significant way.
If cuEventRecord() has not been called on either event then CUDA_ERROR_INVALID_HANDLE is returned. If
cuEventRecord() has been called on both events but one or both of them has not yet been completed (that
is, cuEventQuery() would return CUDA_ERROR_NOT_READY on at least one of the events), CUDA_ERROR_NOT_READY
is returned. If either event was created with the CU_EVENT_DISABLE_TIMING flag, then this function will
return CUDA_ERROR_INVALID_HANDLE.
Parameters:
pMilliseconds - Time between hStart and hEnd in ms
hStart - Starting event
hEnd - Ending event
Returns:
CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT,
CUDA_ERROR_INVALID_HANDLE, CUDA_ERROR_NOT_READY
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuEventCreate, cuEventRecord, cuEventQuery, cuEventSynchronize, cuEventDestroy, cudaEventElapsedTime
CUresult cuEventQuery (CUevent hEvent)
Queries the status of all work currently captured by hEvent. See cuEventRecord() for details on what is
captured by an event.
Returns CUDA_SUCCESS if all captured work has been completed, or CUDA_ERROR_NOT_READY if any captured
work is incomplete.
For the purposes of Unified Memory, a return value of CUDA_SUCCESS is equivalent to having called
cuEventSynchronize().
Parameters:
hEvent - Event to query
Returns:
CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_HANDLE,
CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_NOT_READY
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuEventCreate, cuEventRecord, cuEventSynchronize, cuEventDestroy, cuEventElapsedTime, cudaEventQuery
CUresult cuEventRecord (CUevent hEvent, CUstream hStream)
Captures in hEvent the contents of hStream at the time of this call. hEvent and hStream must be from the
same context. Calls such as cuEventQuery() or cuStreamWaitEvent() will then examine or wait for
completion of the work that was captured. Uses of hStream after this call do not modify hEvent. See note
on default stream behavior for what is captured in the default case.
cuEventRecord() can be called multiple times on the same event and will overwrite the previously captured
state. Other APIs such as cuStreamWaitEvent() use the most recently captured state at the time of the API
call, and are not affected by later calls to cuEventRecord(). Before the first call to cuEventRecord(),
an event represents an empty set of work, so for example cuEventQuery() would return CUDA_SUCCESS.
Parameters:
hEvent - Event to record
hStream - Stream to record event for
Returns:
CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT,
CUDA_ERROR_INVALID_HANDLE, CUDA_ERROR_INVALID_VALUE
Note:
This function uses standard semantics.
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuEventCreate, cuEventQuery, cuEventSynchronize, cuStreamWaitEvent, cuEventDestroy,
cuEventElapsedTime, cudaEventRecord
CUresult cuEventSynchronize (CUevent hEvent)
Waits until the completion of all work currently captured in hEvent. See cuEventRecord() for details on
what is captured by an event.
Waiting for an event that was created with the CU_EVENT_BLOCKING_SYNC flag will cause the calling CPU
thread to block until the event has been completed by the device. If the CU_EVENT_BLOCKING_SYNC flag has
not been set, then the CPU thread will busy-wait until the event has been completed by the device.
Parameters:
hEvent - Event to wait for
Returns:
CUDA_SUCCESS, CUDA_ERROR_DEINITIALIZED, CUDA_ERROR_NOT_INITIALIZED, CUDA_ERROR_INVALID_CONTEXT,
CUDA_ERROR_INVALID_HANDLE
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuEventCreate, cuEventRecord, cuEventQuery, cuEventDestroy, cuEventElapsedTime, cudaEventSynchronize
CUresult cuStreamBatchMemOp (CUstream stream, unsigned int count, CUstreamBatchMemOpParams * paramArray,
unsigned int flags)
This is a batch version of cuStreamWaitValue32() and cuStreamWriteValue32(). Batching operations may
avoid some performance overhead in both the API call and the device execution versus adding them to the
stream in separate API calls. The operations are enqueued in the order they appear in the array.
See CUstreamBatchMemOpType for the full set of supported operations, and cuStreamWaitValue32(),
cuStreamWaitValue64(), cuStreamWriteValue32(), and cuStreamWriteValue64() for details of specific
operations.
Basic support for this can be queried with cuDeviceGetAttribute() and
CU_DEVICE_ATTRIBUTE_CAN_USE_STREAM_MEM_OPS. See related APIs for details on querying support for specific
operations.
Parameters:
stream The stream to enqueue the operations in.
count The number of operations in the array. Must be less than 256.
paramArray The types and parameters of the individual operations.
flags Reserved for future expansion; must be 0.
Returns:
CUDA_SUCCESS, CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_NOT_SUPPORTED
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuStreamWaitValue32, cuStreamWaitValue64, cuStreamWriteValue32, cuStreamWriteValue64,
cuMemHostRegister
CUresult cuStreamWaitValue32 (CUstream stream, CUdeviceptr addr, cuuint32_t value, unsigned int flags)
Enqueues a synchronization of the stream on the given memory location. Work ordered after the operation
will block until the given condition on the memory is satisfied. By default, the condition is to wait for
(int32_t)(*addr - value) >= 0, a cyclic greater-or-equal. Other condition types can be specified via
flags.
If the memory was registered via cuMemHostRegister(), the device pointer should be obtained with
cuMemHostGetDevicePointer(). This function cannot be used with managed memory (cuMemAllocManaged).
Support for this can be queried with cuDeviceGetAttribute() and
CU_DEVICE_ATTRIBUTE_CAN_USE_STREAM_MEM_OPS. The only requirement for basic support is that on Windows, a
device must be in TCC mode.
Parameters:
stream The stream to synchronize on the memory location.
addr The memory location to wait on.
value The value to compare with the memory location.
flags See CUstreamWaitValue_flags.
Returns:
CUDA_SUCCESS, CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_NOT_SUPPORTED
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuStreamWaitValue64, cuStreamWriteValue32, cuStreamWriteValue64 cuStreamBatchMemOp,
cuMemHostRegister, cuStreamWaitEvent
CUresult cuStreamWaitValue64 (CUstream stream, CUdeviceptr addr, cuuint64_t value, unsigned int flags)
Enqueues a synchronization of the stream on the given memory location. Work ordered after the operation
will block until the given condition on the memory is satisfied. By default, the condition is to wait for
(int64_t)(*addr - value) >= 0, a cyclic greater-or-equal. Other condition types can be specified via
flags.
If the memory was registered via cuMemHostRegister(), the device pointer should be obtained with
cuMemHostGetDevicePointer().
Support for this can be queried with cuDeviceGetAttribute() and
CU_DEVICE_ATTRIBUTE_CAN_USE_64_BIT_STREAM_MEM_OPS. The requirements are compute capability 7.0 or
greater, and on Windows, that the device be in TCC mode.
Parameters:
stream The stream to synchronize on the memory location.
addr The memory location to wait on.
value The value to compare with the memory location.
flags See CUstreamWaitValue_flags.
Returns:
CUDA_SUCCESS, CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_NOT_SUPPORTED
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuStreamWaitValue32, cuStreamWriteValue32, cuStreamWriteValue64, cuStreamBatchMemOp,
cuMemHostRegister, cuStreamWaitEvent
CUresult cuStreamWriteValue32 (CUstream stream, CUdeviceptr addr, cuuint32_t value, unsigned int flags)
Write a value to memory. Unless the CU_STREAM_WRITE_VALUE_NO_MEMORY_BARRIER flag is passed, the write is
preceded by a system-wide memory fence, equivalent to a __threadfence_system() but scoped to the stream
rather than a CUDA thread.
If the memory was registered via cuMemHostRegister(), the device pointer should be obtained with
cuMemHostGetDevicePointer(). This function cannot be used with managed memory (cuMemAllocManaged).
Support for this can be queried with cuDeviceGetAttribute() and
CU_DEVICE_ATTRIBUTE_CAN_USE_STREAM_MEM_OPS. The only requirement for basic support is that on Windows, a
device must be in TCC mode.
Parameters:
stream The stream to do the write in.
addr The device address to write to.
value The value to write.
flags See CUstreamWriteValue_flags.
Returns:
CUDA_SUCCESS, CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_NOT_SUPPORTED
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuStreamWriteValue64, cuStreamWaitValue32, cuStreamWaitValue64, cuStreamBatchMemOp,
cuMemHostRegister, cuEventRecord
CUresult cuStreamWriteValue64 (CUstream stream, CUdeviceptr addr, cuuint64_t value, unsigned int flags)
Write a value to memory. Unless the CU_STREAM_WRITE_VALUE_NO_MEMORY_BARRIER flag is passed, the write is
preceded by a system-wide memory fence, equivalent to a __threadfence_system() but scoped to the stream
rather than a CUDA thread.
If the memory was registered via cuMemHostRegister(), the device pointer should be obtained with
cuMemHostGetDevicePointer().
Support for this can be queried with cuDeviceGetAttribute() and
CU_DEVICE_ATTRIBUTE_CAN_USE_64_BIT_STREAM_MEM_OPS. The requirements are compute capability 7.0 or
greater, and on Windows, that the device be in TCC mode.
Parameters:
stream The stream to do the write in.
addr The device address to write to.
value The value to write.
flags See CUstreamWriteValue_flags.
Returns:
CUDA_SUCCESS, CUDA_ERROR_INVALID_VALUE, CUDA_ERROR_NOT_SUPPORTED
Note:
Note that this function may also return error codes from previous, asynchronous launches.
See also:
cuStreamWriteValue32, cuStreamWaitValue32, cuStreamWaitValue64, cuStreamBatchMemOp,
cuMemHostRegister, cuEventRecord
Author
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