Device Management

aclError aclrtSetDevice(int32_t deviceId)

ret = acl.rt.set_device(device_id)

Specifies the device used for computation, and implicitly creates the default context, which contains two streams, one default stream, and one stream for internal synchronization. It is a synchronous interface.

If acl.rt.set_device is called for multiple times in a process, acl.rt.reset_device does not need to be called to reset the device resources, because the device resources will be reset when the process exits. It is recommended that acl.rt.set_device and acl.rt.reset_device be used in pairs to reset the device resources that are no longer needed in a timely manner.

The following application scenarios are supported:

• The same device can be specified for computation in different processes or threads.
• If a device is specified in a process, multiple threads in the process can share the device to explicitly create a context (acl.rt.create_context).
• In the multi-device scenario, acl.rt.set_device can be called in the process to switch to another device. acl.rt.set_current_context is recommended for switching between devices, which is more efficient than using acl.rt.set_device.

device_id: int, device ID.

After acl.rt.get_device_count is called to obtain the number of available devices, the value range of device ID is [0, number of available devices minus 1].

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

None

None

aclError aclrtResetDevice(int32_t deviceId)

ret = acl.rt.reset_device(device_id)

Resets the computing device and releases the resources (including the default context and stream, and all streams created in the default context) on the device. It is a synchronous interface. If a task in the default context or stream is not complete, resources will be released after the task is complete.

device_id: int, device ID.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

If there are explicitly created contexts, streams, or events on the device to be reset, you are advised to follow the following calling sequence before resetting. Otherwise, exceptions may occur.

The interfaces calling sequence is as follows: call acl.rt.destroy_event to release the event or call acl.rt.destroy_stream to release the explicitly created stream --> call acl.rt.destroy_context to release the explicitly created context --> call acl.rt.reset_device.

None

aclError aclrtGetDevice(int32_t *deviceId)

device_id, ret = acl.rt.get_device()

Obtains the IDs of devices in use. It is a synchronous interface.

None

device_id: int ID of the device in use.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

If neither acl.rt.set_device nor acl.rt.create_context is called to specify a device, an error is returned when acl.rt.get_device is called.

None

aclError aclrtGetRunMode(aclrtRunMode *runMode)

run_mode, ret = acl.rt.get_run_mode()

Obtains the running mode of the current Ascend AI software stack. It is a synchronous interface.

None

run_mode: int, running mode.

• 0: ACL_DEVICE, running on the Control CPU of the device or on the developer edition.
• 1: ACL_HOST, running on the Host CPU.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

None

None

aclError aclrtSetTsDevice(aclrtTsId tsId)

ret = acl.rt.set_ts_device(ts_id)

Sets the Task Schedule required for computation. It is a synchronous interface.

ts_id: int, Task Schedule required for computation. If the Ascend AI software stack contains only the AICORE Task Schedule, this parameter is invalid and the AICORE Task Schedule is used by default.

• 0: ACL_TS_ID_AICORE. Use the AICORE Task Schedule.
• 1: ACL_TS_ID_AIVECTOR. Use the AIVECTOR Task Schedule.
• 2: ACL_TS_ID_RESERVED

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

None

None

aclError aclrtGetDeviceCount(uint32_t *count)

count, ret = acl.rt.get_device_count()

Obtains the number of available devices. It is a synchronous interface.

None

None

count: int, number of devices.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

None

None