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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