PPT-I/O Systems (3): Clocks and Timers

1 CSE 2431 Introduction to Operating Systems Instructor Adam C Champion PhD Outline Clock Hardware Clock Software Soft Timers 2 Two Types of Clocks Simple clock tied to 110 or 220volt power line causes an interrupt at every voltage cycle 50 or 60 Hz. Sarangi Department of Computer Science Indian Institute of Technology New Delhi India Smruti R Sarangi Pastry 125 brPage 2br Synchronous Systems Asynchronous Systems Outline Synchronous Systems Physical Clocks Quartz Clocks Atomic Clocks GPS Network Spring 2009. L. -9 . Logical Time. 1. Announcements. Project 1 update – Thursday. Due 2/26. HW 1 – due Thursday. 2. Last Lecture . –. Clock Sync Important Lessons. Clocks on different systems will always behave differently. Generated Clocks. The HCC generates two clocks from the . ePLL. 160 MHz clocks and the chip 40 MHz clock, used as a reference:. An 80 MHz clock using a divide by 2 circuit that contains no loops and so is self clearing.. Xen. Bhanu Vattikonda. with . Sambit. Das and . Hovav. . Shacham. 2. Motivation . Project goals. Goals of the paper. Discussion . Future work. Motivation. 3. Recent research efforts have shown that covert channel attacks are possible in the cloud using fine grained timers . Time keeps on slipping, slipping…. Logistics. Last week’s slides online. Sign up on Piazza now. No really, do it now. Papers are loaded in . HotCRP. Sign up for account at . http://cs7780.ccs.neu.edu. Produced by Dave Foord. Terms of use. These timers are free for anyone to use within education or not for profit organisations.. You are entitled to download this presentation and add to your own internal system (e.g. VLE) to distribute to others.. These files have been downloaded and embedded into PP as shockwave flash objects (.swf files) from . http://www.online-stopwatch.com/download-stopwatch/. In PP2007 files can only be linked and not embedded, but if you . Ken Birman. Cornell University. . CS5410 . Fall 2008. . Real time and clocks. Lamport showed that if we care about event ordering, the best option is to use logical clocks. But suppose we care about real time?. Canada. Conseil national de recherches. Canada . Activities in Frequency and Time at the. National Research Council of Canada. Research Officers and Research Council Officers:. John Bernard, Group Leader . Canada. Conseil national de recherches. Canada . Activities in Frequency and Time at the. National Research Council of Canada. Research Officers and Research Council Officers:. John Bernard, Group Leader . October 11, 2018. A.F. Cooper. Context and Motivation. How can we synchronize an asynchronous distributed system?. How do we make global state consistent? . Snapshots / checkpoints. Example: Buying a ticket on Ticketmaster. Countdown timers for PowerPoint Produced by Dave Foord Terms of use These timers are free for anyone to use within education or not for profit organisations. You are entitled to download this presentation and add to your own internal system (e.g. VLE) to distribute to others. Produced by Dave Foord. Terms of use. These timers are free for anyone to use within education or not for profit organisations.. You are entitled to download this presentation and add to your own internal system (e.g. VLE) to distribute to others.. Hadi Esmaeilzadeh. hadi@cc.gatech.edu. . Georgia Institute of Technology. Some slides adopted from Prof. . Milos . Prvulovic. Asynchronous vs. . Synchronious. Glitches and delays are . very. hard to deal with.