With default signal handling, I observe that when a child process keeps in D-state, I can terminate it parent process, and then the D-state child process would become a child of init (pid-1).
继续阅读“Note: The parent of a multi-process program could exit even if it has a D-state child”
I observed that when terminating a process with D-state thread(s), the process would keep in zombie state, instead of being reclaimed by init (pid-1). Here comes the steps to reproduce this behavior.
继续阅读“Note: init not cleaning zombie process if it contains D-state thread(s)”
There's no explicit definition of CPU utilization. Usually, we see CPU time as CPU utilization. The %id, %us, %sy etc seen in vmstat/iostat are CPU time.
These are percentages of total CPU time.
us: Time spent running non-kernel code. (user time, including nice time)
sy: Time spent running kernel code. (system time)
id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.
继续阅读“How Linux measure CPU utilization with Hyper-Threading enabled?”