Linux, Mac, and other UNIX-like systems can show the "load average" information. These numbers tell you, CPU your system, hard drive, and how busy the other resources. They seem hard to understand, but to know them is actually very easy.
Whether you are using Linux desktop or server version, also, or Linux-based router firmware, Linux or BSD-based network-attached storage system, and even Mac OS X, you are likely to see anywhere "load average" of measure.
Load VS average load
On UNIX-like systems, including Linux system, the system load is used to evaluate the implementation of the measure of how much work, this metric is out with a digital display. A computer is completely idle, the average load is zero. Each process is running, whether it is being used or waiting for CPU resources, will give an average load plus 1. So if your system load average is 5, indicating that there are five processes are using or waiting for CPU.
The traditional UNIX systems are generally only wait for the process of the CPU count, but Linux is also waiting for other resources to be counted into the process. For example those who are waiting for the hard disk read and write process.
For its part, the load parameter does not mean anything, if some of the processes are using CPU, your computer might load to zero in an instant, and in another instant they may load of 5 ,. Even if you can know the number of the load at any given time, these figures basically does not make sense.
This is the UNIX-like systems do not show the cause of the current moment load. They use an average load - over several time periods, the average computer load. These will tell you that your computer in the end how much work is performed.
View average load
The average load can be displayed on the terminal as well as different graphics tools, including command-line and gnome system monitoring tools. In fact, check your average load simplest and most standard way is to run "uptime" command in a terminal. This command displays your computer's average load, as well as the computer is turned on time.
uptime command can be run on Linux, Mac OS X or other UNIX-like systems. If you are using Linux or BSD-based device has a web interface - such as DD-WRT firmware or NAS routing system - you'll likely see the average load information on the status page.
Understand the average load
You first see average load, this figure looks completely pointless. The following is a sample output load average
load average: 1.05, 0.70, 5.09
From left to right, these figures show it to you in the past 1 minute past 5 minutes, the average load over the last 15 minutes. In other words, the above output means:
Past minute load average: 1.05
Over the past five minutes load average: 0.70
Over the past 15 minutes load average: 5.09
Output time period is omitted to save space, as long as you are familiar with the time period, you can quickly sweep over the average number of loads and understand what they mean.
Exactly speaking, these numbers in the end what it means
Let's use the above numbers to understand the real meaning of the average load. Suppose you are using a single-processor system, these numbers will tell us:
In the past 1 minutes: computer overload average of 5%. On average, .05 processes are waiting for CPU. (1.05)
In the past 5 minutes: CPU 30% of the time remain idle. (0.70)
In the past 15 minutes: The average computer overload 409%. On average, 4.09 process is waiting CPU. (5.09)
Your system may have more than one CPU, or a multi-core CPU. Then the average load will be a little different. For example, if you load average on a single-processor system is 2, which means that your system is overloaded 100% - the entire time cycle, when a process when using the CPU, another process is waiting for CPU. However, in the two-CPU system, which just means that the resource entirely - then the entire time period, the use of two different processes in two different CPU. On a four-CPU system, indicating that resource usage is half - two processes use two CPU, two CPU idle.
To understand the significance of digital load average, you need to know the number of your system CPU, CPU load average of 6.03 means that a single system is severely overloaded, but in the eight-CPU system was running well represented.
The average useful load on the server and embedded systems, you can glance over to make sure your system is running. If overloaded, you may want to deal with what those wasteful process, provide more hardware resources, or some of the work is to be transferred to another system.