Do we have the separate metrics for each namespace

[rex0654335]

We are using the namespace to separate data between users and it works well.
But the metrics from the info command stats didn't separate by namespace as well.
As a user, we want to know the speed of commands for each namespace.

用了namespace 来隔离业务，这个功能很不错。
通过info command stats 来看所有namespace的执行命令统计是合起来的，
有没有独立统计的指标，适用场景：区分namespace 分别执行了哪些命令，频率是多少，方便后期定位问题

[git-hulk]

@rex0654335 Not now, I think you can convert this to issue and PR is always welcome if you're willing to do this.

[liangyuanpeng]

Have created issue #755