Memory management to execute a program all or part of

  • No School
  • AA 1
  • DoctorSnow2501
  • 48
  • 100% (1) 1 out of 1 people found this document helpful

This preview shows page 40 - 48 out of 48 pages.

Memory Management To execute a program all (or part) of the instructions must be in memory All (or part) of the data that is needed by the program must be in memory Memory management determines what is in memory and when Optimizing CPU utilization and computer response to users Memory management activities Keeping track of which parts of memory are currently being used and by whom Deciding which processes (or parts thereof) and data to move into and out of memory Allocating and deallocating memory space as needed
Image of page 40
File-system Management OS provides uniform, logical view of information storage Abstracts physical properties to logical storage unit - file Each medium is controlled by device (i.e., disk drive, tape drive) Varying properties include access speed, capacity, data-transfer rate, access method (sequential or random) File -System management Files usually organized into directories Access control on most systems to determine who can access what OS activities include Creating and deleting files and directories Primitives to manipulate files and directories Mapping files onto secondary storage Backup files onto stable (non-volatile) storage media
Image of page 41
Mass-Storage Management Usually disks used to store data that does not fit in main memory or data that must be kept for a long period of time Proper management is of central importance Entire speed of computer operation hinges on disk subsystem and its algorithms OS activities Mounting and unmounting Free -space management Storage allocation Disk scheduling Partitioning Protection Some storage need not be fast Tertiary storage includes optical storage, magnetic tape Still must be managed – by OS or applications
Image of page 42
Storage management: Data view dir21: file21.1 file21.2 file21.3 dir22: file22.1 file22.2 file22.3 dir23: file23.1 file23.2 file23.3 01010 10101 10100 10101 10101 10101 10101 10100 10101 01011 10101 10101 10101 File system based view – content visible as files and directories USER FILE SYSTEM DISK SYSTEM Block based view content considered as blocks of data Physical view – all data just a stream of bits
Image of page 43
UNIX UNIX – limited by hardware functionality, the original UNIX operating system had limited structuring. Systems programs Kernel Consists of everything below the system-call interface and above the physical hardware Provides the file system, CPU scheduling, memory management, and other operating-system functions; a large number of functions for one level
Image of page 44
UNIX Structure
Image of page 45
What are possible OS architectures? How do we build an OS that has all the above functions? UNIX like – monolithic – throw everything into one pile and call it layered! Something more structured..
Image of page 46
Layered Vs Microkernel
Image of page 47
With and without virtual machines
Image of page 48

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture