Issues all previously queued OpenCL commands in a command-queue to the device associated with the command-queue.

cl_int clFlush ( cl_command_queue command_queue)


Issues all previously queued OpenCL commands in command_queue to the device associated with command_queue.

clFlush only guarantees that all queued commands to command_queue get issued to the appropriate device. There is no guarantee that they will be complete after clFlush returns.


clFlush returns CL_SUCCESS if the function call was executed successfully. It returns CL_INVALID_COMMAND_QUEUE if command_queue is not a valid command-queue and returns CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

Any blocking commands queued in a command-queue such as clEnqueueReadImage or clEnqueueReadBuffer with blocking_read set to CL_TRUE, clEnqueueWriteImage or clEnqueueWriteBuffer with blocking_write set to CL_TRUE, clEnqueueMapImage or clEnqueueMapBuffer with blocking_map set to CL_TRUE or clWaitForEvents perform an implicit flush of the command-queue.

To use event objects that refer to commands enqueued in a command-queue as event objects to wait on by commands enqueued in a different command-queue, the application must call a clFlush or any blocking commands that perform an implicit flush of the command-queue where the commands that refer to these event objects are enqueued.


OpenCL Specification

Also see


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