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PCI Express System Architecture by MindShare, Inc, Ravi Budruk, Don Anderson, Tom Shanley

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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.

Table 2-3. PCI Express Aggregate Throughput for Various Link Widths
PCI Express Link Widthx1x2x4x8x12x16x32
Aggregate Bandwidth (GBytes/sec)0.51246816

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, ...

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