lect-05 - Computer Science 425 Distributed Systems Lecture...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
2006, 2007, M. T. Harandi Lecture 5-1 Computer Science 425 Distributed Systems Lecture 5 Time & Synchronization
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2006, 2007, M. T. Harandi Lecture 5-2 : A DS consists of a number of processes. : Each process has a state (values of variables). : Each process takes actions to change its state, or to communicate ( send , receive ). : An event is the occurrence of an action. : Events within a process can be ordered by the time of occurrence. : In DS we also need to know the time order of events on different processors & between different processes. Processes and Events
Background image of page 2
2006, 2007, M. T. Harandi Lecture 5-3 : In DS each processor has its own timer. : Timers drift from true real time at different rates. : Maximum Drift Rate (MDR) of a clock depends on clock characterization and the environment. : Max difference between two clocks with similar MDR is 2 * MDR Physical Clocks & Synchronization Max-Synch-Interval = (Max-Acceptable-Diff) / (MDR * 2)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2006, 2007, M. T. Harandi Lecture 5-4 Synchronizing Physical Clocks C i (t): the reading of the software clock i when the real time is t . External synchronization : For a synchronization bound D>0 , and for source S of UTC time, for i=1,2,. ..,N and for all real times t in I . Clocks C i are accurate to within the bound D . Internal synchronization: For a synchronization bound D>0 , for i, j=1,2,. ..,N and for all real times t in I. Clock C i agree within the bound D . , ) ( ) ( D t C t S i < - D t C t C j i < - ) ( ) (
Background image of page 4
2006, 2007, M. T. Harandi Lecture 5-5 : Uses a time server to synchronize clocks : Time server keeps the reference time : Clients ask the time server for time &
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/01/2009 for the course CS CS421 taught by Professor Kirillmechitov during the Summer '09 term at University of Illinois, Urbana Champaign.

Page1 / 18

lect-05 - Computer Science 425 Distributed Systems Lecture...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online