# KernelMonitor.start ## Supported Products > [!NOTE] > > For details about Ascend product models, see [Ascend Product Overview](https://www.hiascend.com/document/detail/en/AscendFAQ/ProduTech/productform/hardwaredesc_0001.html). | Product Type | Supported| | ------------------------------------------- | :------: | | Atlas 350 accelerator cards | √ | | Atlas A3 training products/Atlas A3 inference products| √ | | Atlas A2 training products/Atlas A2 inference products| √ | | Atlas 200I/500 A2 inference products | √ | | Atlas inference products | × | | Atlas training products | × | ## Function Marks the start of Kernel performance data collection. ## Prototype ```python def start(self, cb: Callable[[KernelData], None]) -> MsptiResult: ``` ## Parameter Description

Parameter	Input/Output	Description
cb: callable	Input	Used to pass the profiled Kernel data. Calls the struct KernelData.

## Returns Returns `MsptiResult.MSPTI_SUCCESS` on success, or `MsptiResult.MSPTI_ERROR_INVALID_PARAMETER` if the callback function type is incorrect and the operation fails.