Caching 505 COS 518 Advanced Computer Systems Lecture 9 Michael Freedman Half of 101 Tradeoff Fast Costly small close Slow Cheap large far Based on two assumptions Temporal location Will be accessed again soon ID: 770077
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Caching 50.5* COS 518: Advanced Computer SystemsLecture 9Michael Freedman * Half of 101
TradeoffFast: Costly, small, closeSlow: Cheap, large, far Based on two assumptionsTemporal location: Will be accessed again soonSpatial location: Nearby data will be accessed soon2 Basic caching rule
3 Multi-level caching in hardware https:// en.wikipedia.org /wiki/ Cache_memory
4 Caching in distributed systems Web Caching and Zipf -like Distributions: Evidence and Implications Lee Breslau, Pei Cao, Li Fan, Graham Phillips, Scott Shenker
WebWeb proxies at edge of enterprise networks“Server surrogates” in CDNs downstream of origin DNSCaching popular NS, A recordsFile sharingGnutella & flooding-based p2p networks5 Caching common in distributed systems
6 Caching within datacenter systemsload balancers f ront-end w eb servers DB / backend partitioned identical identical
7 Caching within datacenter systemsload balancers cache f ront-end w eb servers DB / backend partitioned identical identical
8 Caching within datacenter systemsload balancers l ook-through cache f ront-end w eb servers DB / backend partitioned identical identical partitioned
9 Caching within datacenter systemsload balancers l ook-aside cache f ront-end w eb servers DB / backend partitioned identical identical partitioned
10 Caching within datacenter systemsload balancers l ook-aside cache f ront-end w eb servers DB / backend partitioned identical identical partitioned
11 Caching within datacenter systemsload balancers l ook-aside cache f ront-end w eb servers DB / backend partitioned identical identical partitioned
Write-throughData written simultaneously to cache and storageWrite-back Data updated only in cacheOn cache eviction, written “back” to storage12Cache management
13 Caching within datacenter systemsload balancers l ook-aside cache f ront-end w eb servers DB / backend partitioned identical identical partitioned