lsli16

lsli16 - 16-1 Estimating Latency 16-1 Goal: given...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
16-1 16-1 Estimating Latency Goal: given information about events and their handlers ... estimate response times or devise scheduling to insure that deadlines are met. Definitions: Latency [of an interrupt handler or dæmon task to an event]: Time from event occurrence to start of its handler or dæmon task. Response time [of interrupt handler or dæmon task to an event]: Time from event occurrence to response. In class response assumed to be generated at completion of event’s handler. Letaneventoccurat t 1 , its handler start at t 2 and finish at t 3 then the latency is t 2 - t 1 and response time t 3 - t 1 . Run time [of interrupt handler or dæmon task]: The time needed to run 1 on an unloaded system . Actual run time [of interrupt handler or dæmon task]: The time needed to run in a particular situation (considering other CPU activity, etc.). 1 For handlers (which run something like operating system subroutines), run time is total run time. For dæmons (which are tasks managed like any other tasks the OS is running) it’s the amount of run time needed to generate a response. After the response the dæmon will wait for another event, in contrast to a handler which actually finishes execution. At a subsequent event a waiting dæmon moves from the wait state (if the event is handled by a dæmon), while a “fresh” call to a handler is made (if the event is handled by a handler). 16-1 EE 4770 Lecture Transparency. Formatted 12:36, 7 April 1999 from lsli16. 16-1
Background image of page 1

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

View Full DocumentRight Arrow Icon
16-2 16-2 Worst-case latency [of an int. handler or dæmon task to an event]: The longest possible latency given constraints on when events can occur, etc. Worst-case response time [of an int. handler or dæmon task to an event]: The longest possible response time given constraints on when events can occur, etc. Worst-case run time [of an int. handler or dæmon task to an event]: The longest possible actual run time given constraints on when events can occur, etc. For a particular event, response time is always latency plus actual run time. However, the worst-case response time is not necessarily the worst-case latency plus the worst-case actual run-time. Unless otherwise stated, all latencies, actual run times, and response times are worst case. 16-2 EE 4770 Lecture Transparency. Formatted 12:36, 7 April 1999 from lsli16. 16-2
Background image of page 2
16-3 16-3 Classes of problems: One-shot. Assume that each event can occur at most once. Periodic exhaustive. Events periodic, solution found exhaustively. Periodic statistical. Events periodic, solution found using statistical methods. 16-3 EE 4770 Lecture Transparency. Formatted 12:36, 7 April 1999 from lsli16. 16-3
Background image of page 3

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

View Full DocumentRight Arrow Icon
16-4 16-4 Events, Event Types, and Interrupts An event is some occurrence in the process. For example, temperature exceeding a threshold. (This is the definition used throughout the semester.) An event type is a kind of event.
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/11/2011 for the course EE 4770 taught by Professor Staff during the Fall '99 term at LSU.

Page1 / 57

lsli16 - 16-1 Estimating Latency 16-1 Goal: given...

This preview shows document pages 1 - 5. Sign up to view the full document.

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