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Hint-based Acceleration of Web Proxy Cache. Daniela Rosu Arun Iyengar Daniel Dias IBM T.J.Watson Research Center Unversity of Yuan Ze,Syslab Mike Tien mike@syslab.cse.yzu.edu.tw. Outline. 1. Accelerated Web Proxy
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Hint-based Acceleration of Web Proxy Cache Daniela Rosu Arun Iyengar Daniel Dias IBM T.J.Watson Research Center Unversity of Yuan Ze,Syslab Mike Tien mike@syslab.cse.yzu.edu.tw
Outline • 1.Accelerated Web Proxy • 2.Hint Representation • 3.Hint Consistency • 4.Comparison • 5.Proxy Accelerator Cache • 6.Throughput Improvements • 7.Impact of Hint Management • 8.Summary • 8.Conclusion
1.Accelerated Web Proxy • To speed up proxy caches by reducing their cache-miss overhead. • Extended content-based router called a proxy accelerator(PA). • With embedded O.S optimized for communication.
2.Hint Representation • Accurate–information directory scheme (Hash Table) • Approximate-information based on Bloom Filters --bitmap(hint space) PA(entries,hash table) WP(collision counter)
Hint Representation(cont.) --independently & interleaved
3.Hint Consistency • Protocol ensure that the information at the PA site reflects the content of the WP • Protocol choices --entity that identifies the updates --protocol initiator --rate of update messages --exchanged information • Previously proposed --WP-only update --eager hint register
5.Proxy Accelerator Cache • PA should maximize the hit ratio --size , GDS(1) • WP should minimize the Network-related costs
Throughput Improvements(cont.)(PA cpu speed affect improvement)
Throughput Improvements(cont.)(PA-level cache improve throughput)
8.Summary • Bloom Filter-based scheme exhibits lower computation and communication overhead • WP meta-data may reduce its memory hit ratio • Hint look-up overheads are small with respect to the typical request processing overhead • Eagar hint registration reduces update-related overheads and prevents hit ratio reductions caused by update delay • False hit ratio is more significantly affected by hint representation than by update period
9.Conclusion • This miss ratios at proxy caches are often relatively high,we have developed a method to improve the performance of a cluster-based Web proxy by shifting some of its cache miss-related functionality to be executed on a proxy accelerator • Eagar registration is a “must” and that the Bloom Filter-based scheme is more appropriate than the directory scheme for large WP clusters or when PA and WP nodes have comparable power