What is the system load

What is the system load?


In my job we have a data repository running Ubuntu 04/12/03 CLI and when I checked it this morning when I logged in, instead of giving me the normal information, it reported that the information could not be displayed because of the system load above 2 and 2 I was wondering what that means? I had just restarted it because it wasn't responding. Does it have anything to do with the start-up and start-up process?

Reply:


Run the commands or:

The load averages given here are:

Look at my load averages:
This means that in the last minute, an average of 0.05 processes were waiting for resources.

Should you be concerned that the load average is 2? In general, when the load average is greater than the number of CPUs available, an idle process had to wait for a CPU slot.

If the load average is below the output of, don't worry.

See also: What does Load Average mean under Unix / Linux? As Braiam notes, the processes don't just have to wait for the CPU: basics of average usage versus CPU usage







System load or System load average

It is a run queue, that is, a queue of processes waiting for a resource (CPU, I / O, etc.) to become available.

Think of a single core as a single lane with Bridge and Process as cars.

Now the system load is in this situation

  • 0.0 - When there is no traffic on the street.
  • 1.0 -When the traffic on the road is exactly the capacity of the bridge.
  • More than 1 - When the road traffic exceeds the bridge's capacity and the cars have to wait to pass the bridge.

This number is not normalized according to your specifications. In the multiprocessor system, load 2 means 100% utilization of the dual-core processor, load 4 means 100% utilization of the quad-core processor.

You can get your system load with

  • $ Uptime 22:49:47 to 11:47, 4 users, load average: 2.20, 1.03, 0.82

Here are the last three numbers that represent the average system load for 1, 5 and 15 minutes, respectively.

The example above shows that an average of 2.20 processes were waiting to be scheduled in the execution queue in the last minute.




The system load is relevant to the number of CPU cores. For example, if you have a quad-core CPU (4 cores), a value of 1 means the system load is 25% and 4 means 100%.



If you have the Operating time of the Terminals enter , becomes The following is displayed : Load average and three columns of digits, those of one, five and fifteen minutes loaded become. If you have a dual core processor, 2 means 100% utilization, 1 means 50%, etc.





A system load of 2.0 is not very high. On a multi-core system, your CPU may still be partially idle.

A load average is a measure of how congested a CPU core is in relation to the number of processes that want to use it concurrently.

A single-core CPU (single-thread CPU) is assumed below:

  • 0.0

    The CPU does nothing at all. If a process started using the CPU it would be the only one using it.

  • 1,0

    The CPU is being used to its maximum capacity, but there are no conflicts between processes for using the CPU. This means that only a single process is running, so 100% of the CPU time can be used for itself. Alternatively, multiple processes are running, but none of them are using 100% CPU and the combined CPU usage adds up to 100%. They're all still running as fast as they would run even if they had the CPU entirely to themselves.

  • Greater than 1.0

    The CPU is at its maximum and there are multiple processes that want to use it at the same time, so they are running slower than they would otherwise be if they were solely using the CPU. For example, a load average of 3.0 indicates that processes are running at one-third the speed they want to run. A load average of 50.0 indicates that processes are running at 1/50 the speed they want to run because all other processes are running. That is, values ​​higher than 1.0 indicate that the available CPU is being distributed among more and more active processes.

With a multi-core CPU, it is not the meaning of the numbers that changes, but their interpretation. For example, if you have a 4 core CPU, a load of 1.0 still equates to a process with 100% CPU on one core, but there are three other cores. So on a 4-core CPU, the point of maximum efficiency is 4.0 and not 1.0 - and the point at which everything runs at 1/3 efficiency is 12.0 and not 3.0. To add complexity, a single process can have more than one thread, each using its own CPU. So a single process can use 100% of all 4 cores if it has multiple threads.

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