[CentOS] Linux IO Performance Monitor

Hello Friends,

I wanna to ask how to learn disk (read,write) latency on linux server

I use "iostat -kx 5" command to learn latency.

But i cant understand which field show latency, svctm or iowait ?

And if value svctm is gerater than 15 ms can we say there is a slowly io
performance ?

And i wanna to learn can we list io latency and utilization  for per
process?

Thanks.