Understanding the Load Average:
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On Unix-like systems, including Linux, the system load is a measurement of the computational work the system is performing. This measurement is displayed as a number. A completely idle computer has a load average of 0. Each running process either using or waiting for CPU resources adds 1 to the load average. So, if your system has a load of 5, five processes are either using or waiting for the CPU.
If we type 'w' from a linux shell terminal, its output looks like bellow
16:19:10 up 22 days, 44 min, 2 users, load average: 1.05, 0.70, 5.09
From left to right, these numbers show you the average load over the last one minute, the last five minutes, and the last fifteen minutes. In other words, the above output means:
two user till login, server is up 22 days 44 min and 16:19:10 is current time
load average over the last 1 minute: 1.05
load average over the last 5 minutes: 0.70
load average over the last 15 minutes: 5.09
Assuming we’re using a single-CPU system, the numbers tell us that:
over the last 1 minute: The computer was overloaded by 5% on average. On average, .05 processes were waiting for the CPU. (1.05)
over the last 5 minutes: The CPU idled for 30% of the time. (0.70)
over the last 15 minutes: The computer was overloaded by 409% on average. On average, 4.09 processes were waiting for the CPU. (5.09)
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