Providing mechanisms for process synchronization Providing mechanisms for

Providing mechanisms for process synchronization

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Providing mechanisms for process synchronization Providing mechanisms for process communication Providing mechanisms for deadlock handling The operating system is responsible for the following activities in connection with process management:
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1.36 Silberschatz, Galvin and Gagne ©2018 Operating System Concepts – 10 th Edition 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
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1.37 Silberschatz, Galvin and Gagne ©2018 Operating System Concepts – 10 th Edition Storage 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
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1.38 Silberschatz, Galvin and Gagne ©2018 Operating System Concepts – 10 th Edition 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 Free-space management Storage allocation Disk scheduling Some storage need not be fast Tertiary storage includes optical storage, magnetic tape Still must be managed – by OS or applications Varies between WORM (write-once, read-many-times) and RW (read-write)
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1.39 Silberschatz, Galvin and Gagne ©2018 Operating System Concepts – 10 th Edition Performance of Various Levels of Storage Movement between levels of storage hierarchy can be explicit or implicit
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1.40 Silberschatz, Galvin and Gagne ©2018 Operating System Concepts – 10 th Edition Migration of data “A” from Disk to Register Multitasking environments must be careful to use most recent value, no matter where it is stored in the storage hierarchy Multiprocessor environment must provide cache coherency in hardware such that all CPUs have the most recent value in their cache Distributed environment situation even more complex Several copies of a datum can exist Various solutions covered in Chapter 17
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1.41 Silberschatz, Galvin and Gagne ©2018 Operating System Concepts – 10 th Edition I/O Subsystem
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