chuong 04
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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