Visible to Intel only — GUID: jry1481129291721
Ixiasoft
Visible to Intel only — GUID: jry1481129291721
Ixiasoft
4.5.5.2. Transmit Rate Limiters
The rate limiter is a token-based, flow-control mechanism that prevents a packet from being sent into the network unless enough time has passed since the last packet. This feature provides fair bandwidth sharing among agents. You can program the Streaming TX Rate Limiter register (btrl) to control the rate of traffic injection from an agent into the coherency interconnect.
You configure the rate limiter by selecting a maximum transmission rate and adding a maximum token size for that transmission rate in the Streaming TX Rate Limiter register (btrl) register.
In the diagram above, the token count increases over time at a specified rate. The token count saturates when it hits its maximum, which in this example is 3. When a packet is sent on this interface, the token count decrements. This mechanism ensures that the packet transmission rate does not exceed the rate limit except within a small window defined by the token count.
The token count only decrements by one for command transfers. For data transfers, each data beat decrements the token count.