Linux CPU Load

The Load is a little more abstract than it's been seen many times, Mark.

CPU utilization refers to the percentage of CPU consumed during the run

CPU load is in use and waiting for use for a period of time average number of tasks for CPU

This can actually be likened to the road

0 The road is empty

1 The road is slow ...

> 1 over load ....

Multi-core is similar to .....

Here is an example of a blog that illustrates this issue

There is an interesting analogy on the internet, and call to explain the difference between the two, I explained in my own understanding. a public telephone kiosk, there is a person on the phone, four people waiting, each limit the use of the phone for one minute, if someone does not finish the phone within a minute, can only hang up the phone line, waiting for the next round. The phone is the equivalent of the CPU, and the person who is or is waiting for the call is the equivalent of the task. in the use of telephone booths, it is certain that someone will be out of the phone, some people do not call and choose to re-queue, there will be new people in the line here, the number of changes is equivalent to the number of tasks increase or decrease. To count the average load, we counted the number of people for 5 seconds and averaged the statistics at 1th, 5, 15 minutes, resulting in an average load of 1th, 5 and 15 minutes. Some people pick up the phone to play, has been playing 1 minutes, and some people may be in the first 30 seconds to find the phone number, or hesitate to play, after 30 seconds is really on the phone. If you think of the phone as a CPU, the number of people as a task, we say the previous person (Task) CPU utilization is high, the latter one (Task) CPU utilization is low. of course, the CPU does not work in the first 30 seconds, after 30 seconds to rest, just said, some programs involve a lot of computation, so CPU utilization is high, and some programs involved in the calculation of the few, CPU utilization is naturally low. However, regardless of the CPU utilization is high is low, with the number of tasks behind the queue does not necessarily have a relationship. 　

Reference: http://share.blog.51cto.com/278008/495067/

Http://blog.scoutapp.com/articles/2009/07/31/understanding-load-averages