Load (computing)
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Load, in computing, is a measure of the amount of processing a computer system is currently performing, usually in the form of a scalar and as some variation on a percentage. They come in different forms in the cases of differing operating systems. The average load of a computer system is known as the load average.
- On Unix and Unix-like systems the load average is generally given as three scalar numbers, representing the average number of processes ready to run in the last one, five and fifteen minutes. (Note: On Linux – and possibly other, similar Unix variants – one should divide the load average as reported by the uptime or top commands by the number of CPUs before comparing to load averages for any other system. That's because a multi-processor system has a number of processors to select from among the runnable processes. In some systems the number of CPUs is pre-factored into the load average reporting).
- On Microsoft Windows systems, a percentage of CPU load is generally used, with 100% being full CPU utilization.
Note that the load average is a measure solely of CPU utilization. It is only one factor in overall system performance (and often is the least significant).
The optimum load average is approximately 1 (or 100%) since the system is then not wasting any time and no processes are stalled waiting for CPU time.
However, processes which are awaiting I/O, "sleeping" or "blocked" don't contribute to load average. On modern systems it is common for the performance bottlenecks to be disk I/O, network I/O (latency or bandwidth) and memory constraints (which often are translated into disk I/O through the commonly available virtual memory "paging" (and swapping) mechanism).
External links
- UNIX® Load Average by Dr. Neil Gunther (http://www.teamquest.com/resources/gunther/ldavg1.shtml)
Load (program linking and loading)
- When loading compiled programs into computer memory, a program was linked to the relevant program resources, and then the fully resolved codes then were loaded into computer memory, for execution. This type of program is often called a linking loader.
Load (database loading)
- When loading data into a database management system, a program designed to read input data, and then place it into database tables, is called a loader.