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On Controller Performance in Software-Defined NetworksAuthor: Amin Tootoonchian, Sergey Gorbunov, Yashar Ganjali, Martin Casado and Rob Sherwood
Publisher:
Presenter: Yu Hao, Tseng
Date: 2013/05/29
Outline
• Introduction• NOX-MT• Experiment Setup• Controller Throughput• Controller Response Time• Cbench
Introduction
• How fast can the controller respond to data path requests?• How many data path requests can it handle per second?• For example : • NOX handles around 30k flow initiation events per second while
maintaining a sub-10ms flow install time [14].• Kandula et al. [9] found that a 1500-server cluster has a median
flow arrival rate of 100k flows per second.• Benson et al. [2] show that a network with 100 switches can have
spikes of 10M flows arrivals per second in the worst case.
• We present NOX-MT a publicly-available multithreaded successor of NOX.
3
NOX-MT
• NOX is not optimized for performance and is single-threaded.• The techniques to optimize NOX are including : • I/O batching to minimize the overhead of I/O• Port the I/O handling harness to Boost Asynchronous I/O (ASIO)
library• Use a fast multiprocessor-aware malloc implementation
• NOX-MT is far from perfect.• Heavy use of dynamic memory allocation and redundant memory
copies on a per-request basis• Using locking were robust wait-free alternatives exist
Experiment Setup
• Cbench emulates a configurable number of OpenFlow switches that all communicate with a single OpenFlow controller.
• Each emulated switch sends a configurable number of new flow messages to the OpenFlow controller, waits for the appropriate flow setup responses, and records the difference in time between request and response.
• Cbench supports two modes of operation : • Latency• Throughput
Controller Throughput
• Maximum throughput
Controller Throughput (Cont.)
• Relation with the number of active switches
Controller Throughput (Cont.)
• Relation with the load level
Controller Throughput (Cont.)
• Effect of write-intensive workload
Controller Response Time
• Minimum response time• Average response times of all controllers are between 100 and 150
microseconds.
• Maximum response time
Controller Response Time (Cont.)• Relation with the load level
Controller Response Time (Cont.)• Relation with the number of active switches
Cbench
Cbench (Cont.)
Cbench (Cont.)
• http://www.openflow.org/wk/index.php/Controller_Performance_Comparisons
Cbench (Cont.)responses/s min max avg stdev
NOX 42620.00 232301.74 203830.60 57337.18
POX 7764.75 7939.25 7875.25 54.54