v18stanford.edu-Technology_and_Operating_Systems

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http://w w w .stanford.edu/~ouster/cgi-bin/cs140-w inter12/lecture.php?topic=technology January 11, 2012 Technology and Operating Systems Technology and Operating Systems Lecture Notes for CS 140 Winter 2012 John Ousterhout Many of the basic ideas in operating systems were developed 30-40 years ago, when technology was very different. Are these ideas still relevant today and in the future? Technology changes over the last 25 years: CPU speeds: 15 MHz -> 2 GHz (133x) Memory size: 8 MBytes -> 4 GBytes (500x) Disk capacity: 30 MBytes -> 500 GBytes (16667x) Disk transfer rate: 2 MBytes/sec -> 100 MBytes/sec (50x) Network speed: 10 Mbits/sec -> 1 Gbit/sec (100x) The role of paging: When originally proposed (1960's): Disk speed: 80ms latency, 250 KBytes/sec transfer Memory size: 256 KBytes (64 pages) Time to replace all of memory: 6.4 sec (random access) 1 sec (sequential) Today: Disk speed: 10ms latency, 100 MBytes/sec transfer Memory size: 4 GB (1,000,000 pages) Time to replace all of memory:
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