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Ixiasoft
Visible to Intel only — GUID: yez1483069441698
Ixiasoft
8.3.4.6.2. Example: Tuning for Specific Throughput Requirements
Consider a system in which masters A, B, and C have the following throughput requirements:
- Master A: 1000 MBps operating at 100 MHz
- Master B: 800 MBps operating at 800 MHz
- Master C: 500 MBps operating at 400 Mhz
We achieve this by using the QoS generators in regulator mode. There are other masters in the system, and these three masters may need to "steal" bandwidth from them to achieve the required throughputs. Therefore, all the other QoS generators are configured in limiter mode to cap their bandwidth usage.
To set up the QoS generators for masters A, B, and C, we can use the settings in the following table.
Master | QoS Mode | QoS Bandwidth | QoS Saturation (register value) 18 |
---|---|---|---|
A | Regulator | 2560 | 64 bytes (saturation = 4) |
B | Regulator | 256 | 256 bytes (saturation = 16) |
C | Regulator | 320 | 128 bytes (saturation = 8) |
Not shown are the master urgencies. When a QoS regulator achieves the required bandwidth the urgency is downgraded to allow other masters to achieve their required bandwidth.
We also set the urgency threshold values, P1 and P0. P1 is the urgency when a master falls below the bandwidth threshold. P0 is the urgency when a master is above the bandwidth threshold. regulator mode ensures a minimum bandwidth to the master, by raising the urgency when the bandwidth falls below the threshold, and downgrading it when the bandwidth is back above the threshold.
For any master the value of P1 must be greater or equal than P0.