5. Performance > Port-to-Port Performance Characteristics
CPS-1848 User Manual
99
June 2, 2014
Formal Status
This document is confidential and is subject to an NDA.
Integrated Device Technology
5.4
Port-to-Port Performance Characteristics
The performance numbers in this section use a simple measurement consisting of a port-to-port traffic model to characterize
the maximum throughput and minimum latency performance of the CPS-1848. In this case, all traffic is of the same size and
priority. Due to the simple type of traffic, the throughput and latency performance numbers do not change with the priority of the
packets.
5.4.1
Packet Latency Performance
shows the 4x, 2x, and 1x mode latency numbers under no congestion with default arbitration and watermark settings.
The numbers are based on the same ingress and egress port widths and baud rates. The minimum latency is the minimum
time an ingress packet takes to appear on the egress port.
Cut-through mode is assumed to be configured when measuring latency performance.
Table 30: 4x/2x/1x Latency Numbers Under No Congestion
Reference Clock
Ingress and Egress
Port Width
Ingress and Egress
Baud Rate (Gbaud)
Minimum Latency (ns)
1
1. Due to the asynchronous ability of the clock frequencies within the CPS-1848, the latency numbers can increase by as much
as two 312.5 MHz clock period and two reference clock (REF_CLK) period.
156.25 MHz
4x mode
6.25
106.0
5,0
111.6
3.125
128.4
2.5
139.6
1.25
195.6
2x mode
6.25
109.2
5.0
115.6
3.125
134.8
2.5
147.6
1.25
211.6
1x mode
6.25
115.6
5.0
123.6
3.125
147.6
2.5
163.6
1.25
243.6
