Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs
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Ixiasoft
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Ixiasoft
5.1.6.10.3. Time-Based Scheduling
Time-based scheduling (TBS) feature is suitable for traffic whose periodicity and rate are predictable. This is an optional feature. To improve the quality-of-service of such traffic:
- The transmit DMA fetches the packet from the host memory for transmission at designated time. This helps the software to setup the transmit descriptors in advance even before packet is ready/available. It reduces the overhead on the software and avoids constant monitoring of the time and helps in preparing descriptors just in time when the packet is targeted to be transmitted.
- The MAC transmits the packet only at the designated/pre-determined time even if the packets are fetched in advance. This helps in maintaining a constant transmission rate that can be consumed by the receiver station; therefore avoiding congestion and excessive buffering in the network.
Description of Time-Based Scheduling
- Full duplex mode
- Link speed is 100Mbps or higher
- MTL and higher configurations
- Configurations in which time-stamping is enabled
Following are the time-based scheduling specific definitions:
- Launch time - The time beyond which MTL can schedule the packet for transmission.
- Fetch time - The time beyond which the Tx DMA can schedule a packet-fetch from the host memory.
- Expiry time - The time beyond which the packet is dropped by MTL.
Enabling the Time-Based Scheduling Feature
Refer to the Setting up the Time-Based Scheduling Function in Programming Model for the EMAC for more information.