3. A system has three processes, Pl, P2, and P3, and four resource classes, whic
ID: 3607126 • Letter: 3
Question
3. A system has three processes, Pl, P2, and P3, and four resource classes, which are 4 tape drives, 2 plotters, 3 scanners, and 1 CD-ROM, respectively. The existing resource vector, C (423 1) () A an instant of time, 1 plotter and 2 scanners are assigned to P1, 2 tape drives and 1 CD-ROM are assigned to P2, I scanner is assigned to P3. Find the current allocation matrix, A, and available resource vector, R. (2) After a quantum of time passed, Pl request for 2 tape drives and Iplotters, P2 requests for 1 tape drive and I scanner, P3 further requests 2 tape drives and 1 CD-ROM. Find the need matrix, N. (3) In above situation, is the entire system deadlocked? If yes, what resources are involved? If not, what is the possible sequence to run these processes?Explanation / Answer
1) Allocation Matrix
r1 r2 r3 r4
p1 0 1 2 0
p2 2 0 0 1
p3 0 0 1 0
r1- tape drive
r2 - plotter
r3 - scanner
r4 -cd-rom
Available Resource Vector (2,1,0,0)
2 Need Matrix
r1 r2 r3 r4
p1 2 1 0 0
p2 1 0 1 0
p3 2 0 0 1
3. Need can not be fullfilled at the same time. It is dead locked.only p1 needs
can be fullfilled. But p2 and p3 needs pertaining to r1,r3 and r4 can not be
fullfilled.
A possible sequence is
run p1 first
run p2 second
run p3 third
1) Allocation Matrix
r1 r2 r3 r4
p1 0 1 2 0
p2 2 0 0 1
p3 0 0 1 0
r1- tape drive
r2 - plotter
r3 - scanner
r4 -cd-rom
Available Resource Vector (2,1,0,0)
2 Need Matrix
r1 r2 r3 r4
p1 2 1 0 0
p2 1 0 1 0
p3 2 0 0 1
3. Need can not be fullfilled at the same time. It is dead locked.only p1 needs
can be fullfilled. But p2 and p3 needs pertaining to r1,r3 and r4 can not be
fullfilled.
A possible sequence is
run p1 first
run p2 second
run p3 third
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