How often does the PCI Express Core insert a SKP ordered set?
SKP ordered sets are scheduled for insertion every 1538 symbol times or about every 6.152 us. However, note that the insertion of the SKP ordered set onto the link must follow the rules in section 18.104.22.168 of the base specification. For example, scheduled SKP ordered sets are transmitted if a packet or ordered set is not already in progress; otherwise they are accumulated and then inserted consecutively at the next packet or ordered set boundary. Consequently, if a packet is in the process of being transmitted and the SKP ordered set timer expires, the SKP is not inserted until the packet is finished with transmission. If the timer expires multiple times during the packet transmission, then the SKPs are accumulated and sent at once when the packet finishes.