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MultiBooks - Tổng hợp IT - PC part 159

Tham khảo tài liệu 'multibooks - tổng hợp it - pc part 159', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Trace routines these entails the dumping display or printing of th program or other contents of the main store during program testing to facilitate error detection - Utilitys are commonly used to perform these functions Copying of files Sorting of data Merging of files Data recovery Reformating of records by reamanging their fields File reorganization Reporting of sys status and usages Question 3. System software There are three main types of memory placement policy - First fit - Best fit - Worst fit 1. First fit policy an incoming job is placed in the first available free space large enough to fit it. This allows the placement decision to be made quickly 2. Best fit policy an incoming job is placed in the free space in which it fits most tightly 3. Worst fit policy an incoming job is placed in the largest possible hole of free space Question 4. Types of scheduling - Scheduling of job is also an important part of any OS. It involves keeping track of and deciding which job is to be executed - Types of scheduling Deadline scheduling First in first out scheduling FIFO Round robin scheduling Shortest job first STF scheduling Shortest remaining time scheduling SRT - More details about types of scheduling In deadline scheduling certains are scheduled to be completed by a specifir time or deadline. Deadline scheduling can be very complex requiring substantial overhead in resource management FIFO scheduling processes are dispatched according to their arrival time in the ready queue. This type of Round robin scheduling is similar to FIFO scheduling but the difference lies in that each job is given a slice of CPU time SJF scheduling shorter jobs are more favoured than longer one. SJF selects job that ensures the next jobs will complete leave the sys as soon as possible SRT scheduling the job will the smallest estimated remaining run time is executed first. In SRT a running job may be replaced by a new job with a shorter estimated run time Chapter 8 MEMORY MANAGEMENT. .