Mutual Exclusion Doorways Doorway is a separation mechanism of two areas Processes which pass a doorway at time T prevent neighbour processes entering the same area at a greater time ID: 537168
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Slide1
A polynomial local solution to Mutual ExclusionSlide2
Doorways
Doorway
is a separation mechanism
of two areas.
Processes which pass a doorway at
time T
prevent
neighbour
processes entering the same area at a greater time
than T until exiting
the doorway.Slide3
Asynchronous Dorway
Enry
Code
Exit
Code
m
1 is the I am
going
in
messageSlide4
BehaviourSlide5
Problem with the Asynchronous
Doorway
Slide6
Synchronous Doorway
A process which desires to enter a synchronous doorway is required to wait for
a situation
in which all its
neighbours
are outside the doorway. This is implemented
by checking for a process the states of its neighbours before it enters the doorway.Slide7
Entry
code
:
Exit
code:Slide8
What Can Go Wrong
?Slide9
What if
W
e
Combine?Slide10