Two-Phase API

An operator API that is called in single-operator API execution mode is usually divided into two phases, for example:

aclnnStatus aclxxXxxGetWorkspaceSize(const aclTensor *src, ..., aclTensor *out, ..., uint64_t *workspaceSize, aclOpExecutor **executor);
aclnnStatus aclxxXxx(void *workspace, uint64_t workspaceSize, aclOpExecutor *executor, aclrtStream stream);

First, aclxxXxxGetWorkspaceSize is called to compute the required workspace size in the process, based on which NPU memory is allocated. Then, aclxxXxx is called to perform computation.

aclxx indicates the operator API prefix, for example, aclnn, while Xxx indicates the operator type, for example, Add.

Note:

• The workspace refers to the temporary memory required by the APIs to complete computation on the AI processor, in addition to the input and output memories.
• The second-phase API aclxxXxx(...) cannot be called repeatedly. For example, the following API call will throw an exception:

  aclxxXxxGetWorkspaceSize(...)  
  aclxxXxx(...)   
  aclxxXxx(...)