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I run gkrellm to monitor my workstation. Total CPU usage usually runs 0-1% at idle; when there is activity, it's usually cyan-colored (user space). It was running clean this morning.
A couple hours ago, I noticed it was running consistently 4-5%, colored orange. top shows a steady 5-6% sy (system - kernel space?), which doesn't show up as %CPU in the process table, so I can't tell from top what is using the cycles.
I did some googling and checked /proc/interrupts, ran vmstat and sar to check interrupt activity, etc. Everything points to IRQ 23, which is running about 12 intr/s. /proc/interrupts shows it as IO-APIC-fasteoi (ehci_hcd:usb1, ehci_hcd:usb2), so apparently a USB device (or maybe bus controller). I don't have that many USB devices attached (one flash disk, a multicard reader, kbd & mouse, UPS, and the printer). I've tried "udevadm trigger" and powered off the printer and removed the flash drive, but the sys% usage remains steady.
How can I find out why so many interrupts are being generated (what device, etc.)?
M Hill
Posted 2014-07-17T22:49:20.853
Reputation: 11
2You think 12 interrupts per second is "so many interrupts"?! Ordinary mouse movement could easily generate that. – David Schwartz – 2014-07-18T01:14:34.657