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Daniel Mosse. Energy-efficient Multi-tier Web Server Clusters. Introduction. Practical use of power control of multi-tier clusters Application: e-commerce or other datacenter usages Goal: meet deadlines AND minimize energy Open software and commodity hardward. Cluster Model.
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Daniel Mosse Energy-efficient Multi-tier Web Server Clusters
Introduction Practical use of power control of multi-tier clusters Application: e-commerce or other datacenter usages Goal: meet deadlines AND minimize energy Open software and commodity hardward
Power Model CPUs can vary frequency and voltage The strategy is: if there is time, slow down processor (and procesing) Real-time tasks have deadlines (that is, tasks must finish by a certain time) How much, then, can we slow down tasks?
CPU speed deadline WCET Smax Smin time Static speed adjustment Assumption: all tasks have the same deadline. Smax Smin time Select the speed based on worst-case execution time,WCET, and deadline
Workload Generation TPC-W Benchmark for e-commerce (Transaction Processing Performance Council) Multiple on-line browser sessions Dynamic page generation and database access Authentication through SSL Real-time properties
Measuring end-to-end time delay WIRT Server node 1 Server node 2 Server node 3 Client Front-end req.php req.php?r=123 Img1.jpg?123 Img2.gif?123 Img3.jpg?123 img1.jpg?123 img2.gif?123 img3.jpg?123
Using a Controller Main metric: Quality of Service Web interaction Web interaction response time (WIRT) Controller metric:Tardiness of a web interaction Tardiness show more precise information about the completion of requests and resource usage
Control servers on-off also! If there are N machines, and we can put some machines to sleep, and turn some machines off How many machines are put to sleep? How many machines are turned off? When do we change state of machines? For machines that are on, how to set speed? Multi-core systems: Heterogeneous vs homogeneous cores Change voltage for each core? What about shared memory?