One example packet processing device includes a buffer, and the packet processing device obtains a to-be-measured packet. In response to determining that occupied storage space in the buffer is less than a preset threshold, the packet processing device reads the to-be-measured information from the buffer, and modifies, based on the to-be-measured information and a first algorithm, a pieces of data in first measurement data corresponding to the to-be-measured packet, where a is a positive integer. In response to determining that occupied storage space in the buffer is greater than or equal to a preset threshold, the packet processing device modifies, based on to-be-measured information and a second algorithm, w pieces of data in second measurement data corresponding to the to-be-measured packet, where w is a positive integer, and w is less than a.