How to understand and read the stack tracing captured by xperf

Hi,

I'm a Enterprise IT Admin and needs to support our internal Windows-based application. I know WPT is a really good performance troubleshooting tools that can tell you the delay by going down to the thread function level. 

I got a stack tracing screenshot like below and just want to know how to read it. As I'm a not a developer, with limited knowledge on this kind of output. 

1. The top one is ntdll.dll!RtUserThreadStart, is it should be read as the function namedRtUserThreadStart was called within the module named ntdll.dll?

2. Then how to understand the "kernel32.dll!BaseThreadInitThunk" which just sit below the top one? Does it mean that BaseThreadInitThunk is a function that was called within function RtlUserThreadStart and it is a function implemented within kernel32.dll module?

3. What's the relationship between kernel32.dll!BaseThreadInitThunk andUSERINIT.EXE!__mainCRTStartup? Why are they in a parallel relationship?

thanks!

Ah_Chao|| MCSE,VCP,EMCSAe