High Load – Low IO – Low CPU usage

central-processing-unitioperformance

I have a system whose load is rather high. As you can see from the top output below, CPU usage and I/O is negligible:

top – 17:31:59 up 4 days, 2:34, 2
users, load average: 1.00, 0.99, 1.00

Tasks: 71 total, 1 running, 70
sleeping, 0 stopped, 0 zombie

Cpu(s): 2.0%us, 2.0%sy, 0.0%ni,
95.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Mem: 960720k total, 707288k used, 253432k free,
67328k buffers

Swap: 2811896k total,
2644k used, 2809252k free, 528928k
cached

PID USER PR NI VIRT
RES SHR S %CPU %MEM TIME+ COMMAND

15310 root 20 0 2512 1128 888
R 2.1 0.1 0:00.05 top

I would appreciate any assistance with isolating the cause(s) of high load for when I/O and CPU are not factors.

Best Answer

The high load can also be caused by a few factors:

  • processes in "uninterruptible sleep" (D in the process list), that's processes waiting for some I/O.
  • hardware issues, causing the system to wait for something (can be I/O).

Please check your process list (ps auxf), for any processes which may be in D state, or look weird.

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