2_multi_stream

Description

This sample demonstrates task synchronization methods between multiple Streams, including Stream synchronization, Event synchronization, and Notify synchronization.

Product Support

This sample supports the following products:

Product	Supported
Ascend 950PR/Ascend 950DT	Yes
Atlas A3 training series products/Atlas A3 inference series products	Yes
Atlas A2 training series products/Atlas A2 inference series products	Yes

Compile and Run

1. Download the sample code to the environment where CANN software is installed. Switch to the sample directory.

cd ${git_clone_path}/example/1_basic_features/stream/2_multi_stream

2. Set environment variables.

# Replace ${install_root} with the CANN installation root directory. The default installation is in the `/usr/local/Ascend` directory.
source ${install_root}/cann/set_env.sh
export ASCEND_INSTALL_PATH=${install_root}/cann

# Set SOC_VERSION and ASCENDC_CMAKE_DIR
# -SOC_VERSION: Ascend AI processor model, such as Ascend910_9362, Ascend910B2, and so on
# -ASCENDC_CMAKE_DIR: The sample involves calling AscendC operators. Configure the AscendC compiler ascendc.cmake path, such as /usr/local/Ascend/cann/x86_64-linux/tikcpp/ascendc_kernel_cmake
source ${git_clone_path}/example/set_sample_env.sh

3. Run the following command to execute the sample.

bash run.sh

CANN RUNTIME API

The key functionality points and their key interfaces involved in this sample are as follows:

• Initialization
  • Call aclInit interface for initialization configuration.
  • Call aclFinalize interface for deinitialization.
• Device Management
  • Call aclrtSetDevice interface to specify the Device for computation.
  • Call aclrtResetDeviceForce interface to forcefully reset the current computation Device and reclaim Device resources.
• Context Management
  • Call aclrtCreateContext interface to create Context.
  • Call aclrtDestroyContext interface to destroy Context.
• Stream Management
  • Call aclrtCreateStream interface to create Stream.
  • Call aclrtSynchronizeStream interface to block and wait for Stream tasks to complete.
  • Call aclrtSetStreamFailureMode interface to set the operation when Stream execution encounters errors. Default is continue on error, can be set to stop on error.
  • Call aclrtDestroyStreamForce interface to forcefully destroy Stream and discard all tasks.
  • Call aclrtSynchronizeStreamWithTimeout interface for timeout waiting. If exceeding specified time, tasks will be discarded.
• Event Management
  • Call aclrtCreateEvent interface to create Event.
  • Call aclrtRecordEvent interface to record Event.
  • Call aclrtStreamWaitEvent interface to block specified Stream waiting for Event to complete.
  • Call aclrtResetEvent interface to reset Event.
  • Call aclrtSynchronizeEvent interface to block and wait for Event to complete.
  • Call aclrtSynchronizeEventWithTimeout interface for timeout waiting. If exceeding specified time, tasks will be discarded.
• Notify Management
  • Call aclrtCreateNotify interface to create Notify.
  • Call aclrtRecordNotify interface to record Notify.
  • Call aclrtWaitAndResetNotify interface to block and wait for Notify and reset.
  • Call aclrtDestroyNotify interface to destroy Notify.
• Memory Management
  • Call aclrtMalloc interface to allocate memory on Device.
  • Call aclrtFree interface to release memory on Device.
• Data Transfer
  • Call aclrtMemcpy interface to implement data transfer through memory copy.

Sample Output

[INFO]  Use stream synchronize.
[INFO]  Applied resource successfully, beging assigning task.
[INFO]  Begin a long task, num += 1.
[INFO]  Stream synchronize.
[INFO]  Begin a short task, num *= 2.
[INFO]  The answer is 2.
[INFO]  Simulate timeout, wait 1000ms, the task will fail.
[ERROR]  Operation failed: aclrtSynchronizeStreamWithTimeout(stream1, kWaitTimeMs) returned error code 507046
[INFO]  Resource cleanup completed.
[INFO]  Use event synchronize.
...
[INFO]  Use notify synchronize.
[INFO]  The answer is 2.
[INFO]  Resource cleanup completed.