week9_wed - CSCC 69H3 Operating Systems Spring 2010...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
CSCC 69H3 Operating Systems Spring 2010 Professor Bianca Schroeder U of T
Background image of page 1

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

View Full DocumentRight Arrow Icon
Before we start some questions: Anybody still working on A2? Anybody whose group has fallen apart?
Background image of page 2
What are possible replacement algorithms? Not-recently-used (NRU) First-in-first-out (FIFO) Least-recently-used (LRU) Least-frequently-used Most-frequently-used Ease of implementation Performance + ~ + ~ - ++ - - - -
Background image of page 3

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

View Full DocumentRight Arrow Icon
What are possible replacement algorithms? Not-recently-used (NRU) First-in-first-out (FIFO) Least-recently-used (LRU) Least-frequently-used Most-frequently-used Ease of implementation Performance + ~ + ~ - ++ - - - -
Background image of page 4
What are possible replacement algorithms? Not-recently-used (NRU) First-in-first-out (FIFO) Least-recently-used (LRU) Least-frequently-used Most-frequently-used Second chance Ease of implementation Performance + ~ + ~ - ++ - - - - + +
Background image of page 5

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

View Full DocumentRight Arrow Icon
Second-Chance Idea: FIFO (First-in-first-out) considers only age NRU (Not recently used) considers only usage Maybe we should combine the two! Second chance algorithm: Don’t evict the oldest page if it has been used. Evict the oldest page that has not been used. Pages that are used often enough to keep reference bits set will not be replaced
Background image of page 6
Modelling Clock 1st page fault: Advance hand to frame 4, use frame 3 2nd page fault (assume none of these pages are referenced) Advance hand to frame 6, use frame 5 R=1 R=1 R=0 0 1 2 3 4 5 6 7 8 Physical Frames
Background image of page 7

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

View Full DocumentRight Arrow Icon
Fixed vs. Variable Space In a multiprogramming system, we need a way to allocate memory to competing processes Problem: How to determine how much memory to give to each process? Fixed space algorithms
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/22/2010 for the course CS CSCC69 taught by Professor Bianca during the Spring '10 term at University of Toronto- Toronto.

Page1 / 23

week9_wed - CSCC 69H3 Operating Systems Spring 2010...

This preview shows document pages 1 - 9. Sign up to view the full document.

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