chuong 04

1

1. Liu c xy ra trng hp tr hon v hn nh (starvation hay indefinite blocking) vi gii thut FCFS?2. Vic phc v khch trong nh hng

Thc khch s n v gi mn n cho mnh,Mi mn n cn thi gian chun b khc nhau

Mc tiu:

Gim thi gian i trung bnh ca cc thc khch

Cch lm no s ph hp?

Thng thng cc nh hng s phc v theo kiu FCFS (!)

3. FCFS: Cho lc gantt sau:

ProcessThi im vo

P10

P24

P38

P438

P540

Hy tnh cc thng s:

a) Thi gian hon thnh trung bnh

b) Thi gian i trung bnh

Process Burst Time

P110

P2 29

P3 3

P4 7

P512 Tt c u n thi im 0

a)Xt cc gii thut FCFS, SFJ, v RR vi quantum time = 10

Gii thut no cho

b)Thi gian i trung bnh nh nht?

c)Thi gian p ng trung bnh tt nht?

d)Thi gian hon thnh trung bnh ca process nh nht?

4. Priority Scheduling. Cho bng sau:

Tin trnh u tinThi gian x l

P1315

P213

P356

P424

P5423

Cc tin trnh c vo theo th t P1,P2,P3,P4,P5 ti thi im 0

V lc gantt v tnh thi gian i trung bnh.5. Xt tp cc tin trnh sau (vi thi gian yu cu CPU v u tin km theo) :

Tin trnhThi im vo RLThi gian CPU u tin

P10103

P2132

P3221

P4312

P5454

V gin Gantt v tnh thi gian i trung bnh v thi gian lu li trong h thng trung bnh (turnaround time) cho cc gii thut?

a) SFJ Preemptive

b) RR vi quantum time = 2,

c) iu phi theo u tin c quyn ( u tin 1 > 2 > ...)

6. Round Robin. Tnh thi gian i trung bnh v thi gian hon thnh trung bnhProcessBurst Time

P110

P229

P33

P47

P512

a) Quantum time = 10

b) Quantum time = 5