1. weight 大于0

如果脚本监测失败，优先级不变，如果成功，优先级增加，如果后续监测失败，则优先级在增加的基础上回退，这个weight不会持续增加或减小，只会存在两个值

2. weight 小于0

如果脚本监测失败，优先级降低，如果成功，优先级不变，这个weight不会持续增加或减小，只会存在两个值


另外，keepalived启动时，不论rise和fall的设置的是多少，首次监测脚本，都会根据上面的原则调整，后续的调整则要只有在进入fall和rise到达之后才会调整



       The  default  weight equals 0, which means that any VRRP instance moni-
       toring the script will transition to the fault state after 
       consecutive  failures  of the script. After that,  consecu-
       tive successes will cause VRRP instances  to  leave  the  fault  state,
       unless  they are also in the fault state due to other scripts or inter-
       faces that they are tracking.

       A  positive  weight  means  that     successes   will   add
         to the priority of all VRRP instances which monitor it.
       On the opposite, a negative weight will be subtracted from the  initial
       priority in case of  failures.


参考：​​https://www.keepalived.org/manpage.html​​