I have a Python script that reads Linux kernel system calls, using LTTng. So with this script I could read all kernel events.I have some IO operations (open and read file) and with this script I am going to analyze kernel events.I need to know how many bytes have been read from cache and how many have been read from disk.Which kernel events show me the number of bytes read from cache and disk? 
Trace Linux Kernel to find how many bytes read from disk in IO operation
linux;linux kernel;io;events