[理工] [OS] Dead Lock
洪逸 作業系統金寶典
p.5-59
47.Consider a snapshit if the system as shown below. Upon the
next request, P1 makes a request for ( 0 4 2 0) and is granted
immediately. What is the minimum number of initial instances
(i.e. the total number of instances before any [rpcess enters the
system) for each resource type to make sure system still in a
safe after P1's request is granted? (答案請以(a b c d) 方式表示)
Allocation Max
A B C D A B C D
P0 0 0 1 2 0 1 1 2
P1 1 0 0 0 1 7 5 0
P2 1 3 5 4 2 4 5 6
P3 0 4 3 2 0 7 5 2
P4 0 0 1 4 0 6 5 6
Ans:
Need
A B C D
P0 0 1 0 0
P1 0 7 5 0
P2 1 1 0 2
P3 0 3 2 0
P4 0 6 4 2
所以最少 = (3,12,12,12)
這題我嘗試過各種算法，
都解不出這個數字呀Q___Q
是要用到定理那兩個算式嗎？ (Maxi <= m , Maxi總合 < n+m這兩個...)
請大大解決
謝謝!!!!!!!!!!!!!
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