Load (computing)

It conventionally appears in the form of three numbers which represent the system load during the last one-, five-, and fifteen-minute periods.

All Unix and Unix-like systems generate a dimensionless metric of three "load average" numbers in the kernel.

In operating systems based on the Linux kernel, this information can be easily accessed by reading the /proc/loadavg file.

[4] This, for example, includes processes blocking due to an NFS server failure or too slow media (e.g., USB 1.x storage devices).

Such circumstances can result in an elevated load average, which does not reflect an actual increase in CPU use (but still gives an idea of how long users have to wait).

For systems with multiple CPUs, one must divide the load by the number of processors in order to get a comparable measure.

On modern UNIX systems, the treatment of threading with respect to load averages varies.

[8] A post on the Linux mailing list considers its +1 tick insufficient to avoid Moire artifacts from such collection, and suggests an interval of 4.61 seconds instead.