So, we don’t seem to have a CPU oversubscription scenario in this case.

%iowait means that the CPU is idle, it just happens to have a synchronous I/O submitted by a thread on it before becoming idle. Let’s confirm this with standard OS level commands, to avoid getting misled by potential GUI magic by the monitoring ~]$ wġ1:49:29 up 13 days, 13:55, 2 users, load average: 3446.04, 1242.09, 450.47 The system load, incorrectly labeled as “runnable processes” by the above monitoring tool, jumped to over 3000! Here’s one example from a Linux database server with 32 CPUs: Troubleshooting high system load on Linux So, on Linux, an absurdly high load figure can be caused by having lots of threads in Uninterruptible sleep (D) state, in addition to CPU demand. On Linux, the system load includes threads both in Runnable (R) and in Uninterruptible sleep (D) states (typically disk I/O, but not always).The thread is either currently running on CPU or waiting in the CPU runqueue for the OS scheduler to put it onto CPU Runnable state means “not blocked by anything”, ready to run on CPU.The load average is an average number of threads over a time period (last 1,5,15 mins) that “compete for CPU” on classic unixes or “either compete for CPU or wait in an uninterruptible sleep state” on Linux The unit of system load metric is “number of processes/threads” (or tasks as the scheduling unit is called on Linux).

On classic Unixes, it only counts the demand for CPU (threads in Runnable state)

The system load metric aims to represent the system “resource demand” as just a single number.

Troubleshooting high system load on Linux.

You can drill down into the “linux system load in thousands” and “high system load, but low CPU utilization” problem patterns too. In this post I will show you how to break down Linux system load by the load contributor or reason. High System Load with Low CPU Utilization on Linux?

Check cpu load linux