I have a machine that is randomly pausing. In top the CPU stats say that the CPU I/O Wait State is high, often 100% for several seconds, splitting the display to show individual CPUs it seems that randomly one or more CPUs is high in wait states, 100%, or near abouts, for seconds at a time.
top is NOT reporting any application with high utilisation when this happens.
I have determined via iotop that the disks are NOT under any load when this happens.
I last night ran the memtest off the install CD, it completed 8 scans without error in 11 1/2 hours.
My question is, does the CPU I/O also have to stop for network I/O or is there some sort of “buffer” between the two. This machine is being accessed via ssh to run X applications on other machines. So network traffic would be constantly high.
openSUSE 11.1 64 bit
Kernel: (from uname) 2.6.27-29-0.1-default #1 SMP x86-64
CPU: (from /proc/cpuinfo) Intel Core 2 Quad CPU Q8400 @ 2.66 GHz
It sees 4 CPUs
Memory: 8 GB
Motherboard: Intel P5QL Pro Chipset P43.
Disk controller: ICH10 southbridge.
Disks: 4 SATA 1TB disks. The / partition is on a md raid mirrored over 2 disks. The other 2 disks are mounted under /mnt
All partitions formated ext3
Swap: is on one of the mirrored disks.
/boot: is on the other disk of the mirror set.
Network: is a PCIe Gigabit LAN Controller connected to a 100 Mbit switch.