Features
P5020 QorIQ Communications Processor Product Brief, Rev. 1
Freescale Semiconductor 19
• Because the FMan has up to 256 policing profiles, any frame queue or group of frame queues can
be policed to either drop or mark packets if the flow exceeds a preconfigured rate.
• Policing and classification can be used in conjunction for mitigating Distributed Denial of Service
Attack (DDOS).
• The policing is based on two-rate-three-color marking algorithm (RFC2698). The sustained and
peak rates as well as the burst sizes are user-configurable. Hence, the policing function can
rate-limit traffic to conform to the rate the flow is mapped to at flow set-up time. By prioritizing
and policing traffic prior to software processing, CPU cycles can be focused on the important and
urgent traffic ahead of other traffic.
3.9.4.2 Queue Manager (QMan)
The Queue Manager (QMan) is the main component in the DPAA that allows for simplified sharing of
network interfaces and hardware accelerators by multiple CPU cores. It also provides a simple and
consistent message and data passing mechanism for dividing processing tasks amongst multiple CPU
cores. The QMan features are as follows:
• Common interface between software and all hardware
— Controls the prioritized queuing of data between multiple processor cores, network interfaces,
and hardware accelerators
— Supports both dedicated and pool channels, allowing both push and pull models of multicore
load spreading
• Atomic access to common queues without software locking overhead
• Mechanisms to guarantee order preservation with atomicity and order restoration following
parallel processing on multiple CPUs
• Two-level queuing hierarchy with one or more Channels per Endpoint, eight work queues per
Channel, and numerous frame queues per work queue
• Priority and work conserving fair scheduling between the work queues and the frame queues
• Lossless flow control for ingress network interfaces
• Congestion avoidance (RED/WRED) and congestion management with tail discard and up to 256
congestion groups with each group composed of a user-configured number of frame queues.
3.9.4.3 Buffer Manager (BMan)
The buffer manager (BMan) manages pools of buffers on behalf of software for both hardware
(accelerators and network interfaces) and software use. The BMan features are as follows:
• Common interface for software and hardware
• Guarantees atomic access to shared buffer pools
• Supports 32 buffer pools. Software and hardware buffer consumers can request both different size
buffers and buffers in different memory partitions.
• Supports depletion thresholds with congestion notifications
• On-chip per pool buffer stockpile to minimize access to memory for buffer pool management
• LIFO (last in first out) buffer allocation policy that optimizes cache usage and allocation
