How to understand "/proc/[pid]/stack"?
How should I understand
/proc/[pid]/stack?
Taken from the man pages for proc:
There are additional helpful pseudo-paths:
[stack] The initial process's (also known as the main thread's) stack.
Just below this, you can find:
[stack:[tid]] (since Linux 3.4)
A thread's stack (where the [tid] is a thread ID). It corresponds to the /proc/[pid]/task/[tid]/path.
Which seems to be what you are looking for.
Nan Xiao is right.
Thread kernel mode stack is under /proc/[PID]/task/[TID]/stack.
you are checking /proc/[PID]/stack, that's the main thread stack so you have only 1. Others are under task folder.
That is for sleep locks. You might also look at perf -g to see spin locks including high system time.