Broadcast and dissemination
LECTURE 5
Broadcast:
Organization of Broadcast data
Flat: broadcast the union of the requested data cyclic.
Skewed (Random):
? broadcast different items with different frequencies.
? goal is that the inter-arrival time between two instances of the same item matches the clients needs.
Multi-Disks Organization
? The frequency of broadcasting each item depends on its access probability.
? Data broadcast with the same frequency are viewed as belonging to the same disk.
? Multiple disks of different sizes and speeds are superimposed on the broadcast medium.
? No variant in the inter-arrival time of each item.
1. Round-Robin Scheduling
? The Round-Robin is designed especially for time sharing systems.
? It is similar FCFS but add preemption concept
? A small unit of time, called time quantum
? Each process gets a small unit of CPU time (time quantum), usually 10-100 milliseconds. After this time has elapsed, the process is preempted and added to the end of the ready queue.
2. Priority Scheduling
A priority number (integer) is associated with each process
The CPU is allocated to the process with the highest priority
(smallest integer ? highest priority)
Problem : Starvation – low priority processes may never execute
Solution : Aging – as time progresses increase the priority of the process
Example of Priority Scheduling
Dissemination
1.Dissemination: Pull
2.Dissemination: Push
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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