On 2018年03月12日 11:19, David Rosenstrauch wrote:
My server's been exhibiting some very strange behavior lately. Every couple of days I run into a situation where one core (core #0) on the quad core CPU starts continuously using around 34% of CPU, but I'm not able to see (using htop) any process that's responsible for using all that CPU. Even when I tell htop to show me kernel threads too, I still am not able to see the offending process. Every process remains under 1% CPU usage (except for occasional, small, short-lived spikes up) yet the CPU usage on that core remains permanently hovering at around 34%. The problem goes away when I reboot, but then comes back with a day or so.
I'm rather stumped as to how to fix this. The server is a bit old, running an up-to-date installation of Arch on a Intel Core 2 Quad Q6600 CPU. Any suggestions anyone might have as to either what might be going on here, or how to go about debugging it would be greatly appreciated.
Thanks!
DR
Can you check whether you have enabled "Detailed CPU time" option in htop's setup (F2 -> Display options -> "Detailed CPU time")? From my experience and understanging, htop's CPU meter is accounting IO-wait/IRQ-response time by default but not showing them differently unless you enabled the "Detailed CPU time" option. And these waiting time is not accounted on each process or kernel thread. Enabling that said option will revail more detailed CPU usage info. High IO-wait or IRQ time is itself an indication of some misbehaving hardware, but at least you can be sure that it is not by more "dangerous" malwares or attacks.