Question

考虑到三个服务器A，B，C，其中A可以处理50％的流量，B可以处理30％的流量，C可以处理20％的流量，得出一个公式来有效地分配负载。服务器的当前负载也是该功能的输入。

我无法想出他要求的“公式”。这个问题有什么具体的答案吗？

Answer 1

分发可能适用的负载有几种不同的方法。

案例1.随机分配与每个服务器负载成比例偏差：

for each request
  let x = uniformly distributed random number between 0 and 1
  if x <= 0.5
    goto A
  else if x <= 0.8
    goto B
  else
    goto C

案例2. Round-Robin与每个服务器负载成比例地偏向：

let x = new list
push A on x 5 times
push B on x 3 times
push C on x 2 times

for each request
  y = pop x
  goto y
  push y to back of x

案例3.忘记当前负载的假定容量和轮询

let La = A, load of A
let Lb = B, load of B
let Lc = C, load of C

goto argmin (La,Lb,Lc)

Answer 2

基本上，计算在每个服务器上提供服务的相对成本，并在一些小的固定时间段内，将发送到所述服务器的请求的总成本相加。类似的东西：

Cost_A = 20/50
Cost_B = 20/30
Cost_C = 20/20

Running_Total_A = 0 
Running_Total_B = 0
Running_Total_c = 0

while true: 
   If One minute has passed:
     Running_Total_A = 0 
     Running_Total_B = 0
     Running_Total_c = 0

   IF (Min(Running_Total_A,Running_Total_B,Running_Total_C) == Running_Total_A):
     Running_Total_A += Cost_A
     RouteTo(A)
   ELSE IF (Min(Running_Total_A,Running_Total_B,Running_Total_C) == Running_Total_B):
     Running_Total_B += Cost_B
     RouteTo(B)
   ELSE IF (Min(Running_Total_A,Running_Total_B,Running_Total_C) == Running_Total_C):
     Running_Total_C += Cost_C
     RouteTo(C)

查找负载最少的服务器

2 个答案: