最初由 bye 发布
我再补充一点,就是加拿大的红绿灯特别的S.B.,好象全是遵守固定的时间表,一点动态调整的余地都没有.
比如说吧,你等一个红灯,另一个方向一辆等待的车都没有,他还照样开绿灯.而你等了好长时间也不见动静.
而美国的路口呢,至少我经历过的一个,如果没有人等绿灯,他就会很长时间不变,这样动态调整的程序其实会怎么难整,加拿大人就是懒,懒得掉渣.
Technically, american's policy may not be better
than canada's.
It is like a network (the whole high way system).
Your crosspoint is like a node in the network.
Canada's policy is like traffic shaping, even though
the node has free resource and someone is waiting for
service, it will not get service until it waits enough
time. it is not work-conserving. In a single node case,
this is not efficient.
American policy is like the work conserving case.
Whenever there is free resource and user waiting, the
user get service.
But what would be like in the whole network? serious
congestion maybe caused by the work conserving policy!
Since the traffic is not regulated and the burstness
may be caused internal the network!
You cannot judge the performance of the whole system
in a single node case. In canada, you wait more times,
but each time, you just wait for the green light. In
american, you may just wait for once, but for hours.