From time to time, often after I've restored from sleep or finished playing a Steam game, one of my CPU cores is pinned at 100% with no indication of what might be doing it. Running htop, btop, or GNOME system monitor all show the same thing: CPU0 at 100% while the rest are doing near-nothing, and no process in particular seems to be using those resources.
If I restart, it's back to normal, and sometimes I can play a game in Steam or let the computer go to sleep and it doesn't do this, but it happens often enough that's annoying/confusing so I'd like to know if there's a way to either (a) diagnose which processes are using which CPU cores, or (b) somehow "reset" the checking of these values to make sure that something's not just being misreported.
This is a desktop system running Arch & GNOME.
since your CPU has 16 threads ("cores" but not really cores, you probably only have 8 of that), if a process uses up all the capacity of a single core, that will have a 100/16 = ~6% cpu usage. In my experience looking for this really works.. at least on windows, please don't hurt me. it should on linux too, but there I don't have it at such a visible place.
this may not work that much though when your system is under a higher load, and the process you're looking for also has a higher CPU usage, like 30% or something.
in this case you'll want to look for the cpu usage of the individual threads of processes with a higher cpu usage. if you have a process which has a thread with 6% cpu usage (in case of a 16 hardware thread cpu), then that process is at fault. by looking at the name of the thread you may even find out what is its purpose.
Nah fam, you're hurt enough.