Assignment2: Calculating of Weighted Mean

1
Assignment2 Calculating of Weighted Mean
Each process Pi keeps value vi and weight wi.
v1 w1
P1
v2 w2
P2
P3
v3 w3
P5
v5 w5
P4
v4 w4
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Assignment 2 (cont)

• The Mailer is a Server
• All threads are Clients
• There are only two main modules in the System
• the Scheduler
• the Mailer

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The Computing System
P2
P3
Scheduler
P1
P5
Msgs
Mailer
P4
Shell
Net creator
(User interface)
System programs
Application programs
OS
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more in the 2nd Assignment ..

• Processes are simulated by threads
• No process tree, but, the special thread - the
  Shell - creates all other threads
• The thread-table is very simplistic, the
  Scheduler keeps track on whos ready
• Inter process communication is enabled for all
  threads - performed by the Mailer
• Threads have IDs, essential for the routing

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A view of the 2nd Assignment ..

• The system is a set of concurrently executing
  threads, all created by the shell
• Threads use system calls for actions related
  to resources (send message)
• There is only one independent module in the
  System
• the Scheduler

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system calls in the 2nd Assignment ..

• System calls are simulated by
• send(), receive()
• But, there are all the real system calls
• suspend(), block(), release()
• So, the best policy is to let these
  extra-functions be called from the system
  module
• Remember, the (global) function called is part
  of the thread of control...

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The Mailer
MailBoxMailer Size unbound
send
T3
m
m
. . .
pop
send
Thread Ti
T8
MailBox1 Size 5
push
m
m
T1
receive
. . .
MailBoxn Size 5
m