PCI Express Performance and Data Transfer Efficiency
As of May 2003, no realistic performance and efficiency numbers were available. However, Table 2-3 shows aggregate bandwidth numbers for various Link widths after factoring the overhead of 8b/10b encoding.
|PCI Express Link Width||x1||x2||x4||x8||x12||x16||x32|
|Aggregate Bandwidth (GBytes/sec)||0.5||1||2||4||6||8||16|
DLLPs are 2 doublewords in size. The ACK/NAK and flow control protocol utilize DLLPs, but it is not expected that these DLLPs will use up a significant portion of the bandwidth.
The remainder of the bandwidth is available for TLPs. Between 6-7 doublewords of the TLP is overhead associated with Start and End framing symbols, sequence ID, TLP header, ...