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Pertemuan 7Masalah-masalah pada Komunikasi

antar Prosesdan

Penjadwalan Batch

Matakuliah : T0316/sistem Operasi

Tahun : 2005

Versi/Revisi : 5

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :• mendemonstrasikan masalah klasik dalam

komunikasi antar proses dan mendemonstrasikan penjadwalan proses pada sistem batch (C3)

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Outline Materi

Classical IPC Problems– Dining Philosophers problem– The Reader and Writers problem– The Sleeping Barber problem

Batch Scheduling– FCFS– Shortest Job First– Shortest Remaining Time Next– Three-Level Scheduling

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Classical IPC problems

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Dining Philosophers (1)

• Philosophers eat/think• Eating needs 2 forks• Pick one fork at a time • How to prevent

deadlock

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Dining Philosophers (2)

A non-solution to the dining philosophers problem

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Dining Philosophers (3)

Solution to dining philosophers problem (part 1)

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Dining Philosophers (4)

Solution to dining philosophers problem (part 2)

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The Readers and Writers Problem

A solution to the readers and writers problem

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The Sleeping Barber Problem (1)

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The Sleeping Barber Problem (2)

Solution to sleeping barber problem.

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Scheduling

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Introduction to Scheduling (1)

• Bursts of CPU usage alternate with periods of I/O wait– a CPU-bound process– an I/O bound process

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Introduction to Scheduling (2)

Scheduling Algorithm Goals

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Scheduling in Batch Systems (1)

First-Come First-Serve

Processes are assigned the CPU in the order they request it

Adv:

Easy to understand and easy to program

Disadv:

Short job may wait too long if long job is in front of it

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Shortest job first scheduling

• Only optimal when all jobs are available simultaneously

the run time must be known in advance

Shortest remaining time next

• The scheduler always chooses the process whose remaining run time is the shortest

the run time must be known in advance

Scheduling in Batch Systems (2)

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Scheduling in Batch Systems (3)

Three level scheduling