Hello, I am using FreeBSD 8.2-RELEASE on a new computer intended to be used as a backup server on my home LAN. After leaving the system running for a few days, the processor begins to get overwhelmed with processing interrupts on either ehci0 or ehci1. Here is some background on my installation: I am using the "GELI + ZFS" configuration described in another post. I basically followed this guide to the letter, with the exception of not installing a swap partition; the machine has 6 GB of RAM. The important thing to note from this guide is that I have the computer set to boot from a USB thumbdrive, which is physically removed once the operating system has finished booting. Here is some output from top, to illustrate the problem: Code:last pid: 13766; load averages: 0.00, 0.00, 0.00 up 3+03:18:46 02:52:33 42 processes: 1 running, 41 sleeping CPU: 0.0% user, 0.0% nice, 0.0% system, 19.5% interrupt, 80.5% idle Mem: 29M Active, 6844K Inact, 4147M Wired, 16K Cache, 1536M Free Swap: PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 1137 root 1 44 0 9372K 2100K select 0 0:28 0.00% top ... This is what vmstat -i has to say about it: Code:interrupt total rate irq16: ehci0 11672434566 43042 irq19: atapci0+ 611601 2 irq23: ehci1 544034 2 cpu0: timer 542358880 1999 irq256: re0 9199472 33 cpu1: timer 542348239 1999 Total 12767496792 47080 Here's the relevant portions of devinfo -v: Code:nexus0 ... acpi0 ... pcib0 pnpinfo _HID=PNP0A08 _UID=0 at handle=\_SB_.PCI0 pci0 ... ehci0 pnpinfo vendor=0x8086 device=0x3b3c subvendor=0x1462 subdevice=0x7636 class=0x0c0320 at slot=26 function=0 handle=\_SB_.PCI0.USBE usbus0 uhub0 uhub2 pnpinfo vendor=0x8087 product=0x0020 devclass=0x09 devsubclass=0x00 sernum="" release=0x0000 intclass=0x09 intsubclass=0x00 at bus=1 hubaddr=1 port=0 devaddr=2 interface=0 ... ehci1 pnpinfo vendor=0x8086 device=0x3b34 subvendor=0x1462 subdevice=0x7636 class=0x0c0320 at slot=29 function=0 handle=\_SB_.PCI0.EUSB usbus1 uhub1 uhub3 pnpinfo vendor=0x8087 product=0x0020 devclass=0x09 devsubclass=0x00 sernum="" release=0x0000 intclass=0x09 intsubclass=0x00 at bus=1 hubaddr=1 port=1 devaddr=2 interface=0 ukbd0 pnpinfo vendor=0x413c product=0x2105 devclass=0x00 devsubclass=0x00 sernum="" release=0x0352 intclass=0x03 intsubclass=0x01 at bus=2 hubaddr=4 port=1 devaddr=4 interface=0 ... For this particular boot, the bootable USB thumbdrive was on ehci1 before it was removed. I configured a cronjob to log the output of vmstat -i every half hour. Today, between 10:29 and 10:59 local time, the interrupt rate of ehci0 jumped from 1 to 1967. It has been steadily rising since then. The only cronjob that is scheduled to run between those times is an ntpdate, and that task runs every hour. The only USB device plugged into the machine is a USB keyboard. The computer itself has a "MSI H55M-P33 Intel H55 LGA1156" motherboard, four SATA HDDs, and a 2.8 GHz Intel Pentium G6950. Does anyone know what might cause this problem, or what I might be able to do to track down the cause? I'm not very experienced with non-Windows systems so I'm not sure what to try next. Thank you for any assistance!