Ning Weng ANCS 2005 Design Considerations Design Considerations for Network Processors for Network Processors Operating Systems Operating Systems Tilman Wolf 1 , Ning Weng 2 and Chia- Hui Tai 1 1 University of Massachusetts Amherst 2 Southern Illinois University Carbondale
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Ning WengANCS 2005 Design Considerations for Network Processors Operating Systems Tilman Wolf 1, Ning Weng 2 and Chia-Hui Tai 1 1 University of Massachusetts.
Ning WengANCS NPOS Characteristics Network processing very dynamic process ─ Many different network services and protocols ─ Processing requirements depend on network traffic ─ New algorithm for existing applications, e.g., flow classification Managing network processors is difficult ─ Multiple embedded processor cores ─ Limited memory and processing resources ─ Tight interaction between components Processing elements cannot implement complex OS NPOS requirements: ─ Lightweight ─ Consider multiprocessor nature ─ Adaptive to changes in workload
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Ning Weng ANCS 2005
Design Considerations for Design Considerations for Network Processors Network Processors Operating SystemsOperating Systems
Tilman Wolf1, Ning Weng2 and Chia-Hui Tai1
1University of Massachusetts Amherst2Southern Illinois University Carbondale
Ning Weng ANCS 2005 2
Network Processor SystemsNetwork Processor Systems• System outline:
• Network Processor Operating System (NPOS)─ Manages multicore embedded system─ Considers workload requirements and network traffic
RouterPort
Network Processor
SwitchingFabric
Port
Port
packets
Port
Network Processor
Network Processor
Network Processor
Parallel Architecture
Proc. Proc. Proc.
Proc. Proc. Proc.
Network Processor Operating System
Network Traffic
WorkloadApplication
1
Application 3
Application 2
Ning Weng ANCS 2005 3
NPOS CharacteristicsNPOS Characteristics• Network processing very dynamic process
─ Many different network services and protocols─ Processing requirements depend on network traffic─ New algorithm for existing applications, e.g., flow
classification• Managing network processors is difficult
─ Multiple embedded processor cores─ Limited memory and processing resources ─ Tight interaction between components
• Processing elements cannot implement complex OS• NPOS requirements:
─ Lightweight─ Consider multiprocessor nature─ Adaptive to changes in workload
Ning Weng ANCS 2005 4
ComparisonComparison• Major differences to workstation/server OS
─ Separation between control and data path─ Limited/no user interactions─ Highly regular and “simple” applications─ Processing dominates resource management─ No separation of user-space and kernel-space
• Differences to others NP runtime environments─ Others: NEPAL, Teja, Shangri-La─ Multiple packet processing applications─ Run-time remapping─ Considers parallelism within application─ Not limited to certain hardware
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OutlineOutline• Introduction• NPOS architecture
─ Our approach─ Design parameters
• Application workload─ Partitioning and mapping
• Traffic characterization─ Variation in processing demand
• Results and tradeoffs─ NPOS parameters─ Quantitative tradeoffs
• Example NPOS scenarios
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Architecture of NPOSArchitecture of NPOS• Applications
• Monolithic (one single node): does not exploit parallelism
• Very fine-grained: requires excessive mapping effort
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Traffic CharacterizationTraffic Characterization• We can find a configuration for one particular workload
─ Workload depends on traffic, which changes dynamically• Need to adapt to traffic• Cannot adapt for every packet
─ Need to sample traffic and find configuration for longer time• Traffic models for NPOS:
─ Static: cannot adapt, generally not suitable─ Batch: batch of packet buffered, perfect prediction, long delay─ Predictive batch: sampling of traffic, prediction for entire batch
• Takes advantage of temporal locality of network traffic• Key NPOS parameters:
─ Batch size: number of packets processed using one workload allocation
─ Sample size: number of packets used to predict batch workload• Impact Metric: traffic variation
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TrafficTraffic VariationVariation• Measure for traffic variation v
─ Metric for how different traffic is from what we expected
• ei,j(a): estimated number of packets for application a
• pi,j(a): the actual number of packets for application a
─ Workload allocated according to sample of size l
─ What fraction of packets in batch of size b cannot be processed?
─ Ideal: v=0 all packets match with workload allocation─ Figure:
• Next steps─ Integrate memory management─ Consider different traffic prediction algorithms─ Develop prototype system on IXP platform
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ReferencesReferences[1] Memik, G., and Mangione-smith, W. H. NEPAL: A framework for
efficiently structuring applications for network processors. In Proc. of Second Network Processor Workshop (NP-2) in conjunction with Ninth International Symposium on HPCA, Feb, 2003.
[2] TEJA TECHNOLOGIES. TejaNP Datasheet, 2003. http://www.teja.com.[3] Kokku, R., Rich, T., Kunze, A., Mudigonda, J., Jason, J., and Vin, H. A
case for run-time adaptation in packet processing systems. In Proc. of the 2nd Workshop on Hot Topics in Networks , Nov. 2003.
[4] Ramaswamy, R., Weng, N., and Wolf, T. Application analysis and resource mapping for heterogeneous network processor architectures. In Proc. of Third Workshop on NP-3, Feb, 2004.
[5] Weng, N. and Wolf, T., Pipelining vs. multiprocessors - choosing the right network processor system topology, in Proc. of Advanced Networking and Communications Hardware Workshop, June, 2004.
[6] Weng, N., and Wolf, T. Profiling and mapping of parallel workloads on network processors. In Proc. of The 20th Annual ACM Symposium on Applied Computing, March, 2005.