How to calculate total Linux CPU usage from SAR -u report?

The sar -u command in Linux gives detailed information on Linux CPU usage. Here’s a breakdown of the representation of each column in the output.

%user: user-level CPU.

When a program is running at the user level, the CPU utilization percentage is being measured. During this period, user processes and programs are executed.

%nice: priority level.

The CPU usage percentage happened while the application was running at the user level and had good priority. Processes manage their priorities by using pleasant values.

%system: system level.

The percentage of CPU utilization that occurred while executing at the system level (kernel level).

This includes time spent on executing system calls and handling interrupts.

%iowait: wait time.

The CPU or CPUs were idle for a certain percentage of time while the system had an outstanding disk I/O request. High iowait values might suggest that the system frequently waits on disk operations..

%steal: steal time.

The virtual CPU or CPUs spent a percentage of time waiting involuntarily while the hypervisor was servicing another virtual processor in virtualized environments where resources are shared among multiple virtual machines.

%idle: System idle process.

The CPU or CPUs were idle and the system did not have an outstanding disk I/O request for a certain percentage of time. High idle values indicate that the CPU has been underutilizing

$ sar -u 1 3
Linux 5.4.0-72-generic (hostname)     08/05/2024     _x86_64_    (4 CPU)

12:00:01 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
12:00:02 AM     all      3.00      0.00      1.00      0.50      0.00     95.50
12:00:03 AM     all      4.00      0.00      2.00      0.00      0.00     94.00
12:00:04 AM     all      2.00      0.00      1.50      0.00      0.00     96.50
Average:        all      3.00      0.00      1.50      0.17      0.00     95.33

Explanation:

Timestamp (12:00:01 AM):

The time at which the data was collected.

CPU (all):

The CPU field indicates that the data is aggregated across all CPUs.
If you have multiple CPUs, sar can report individual CPU stats.

%user (3.00): user-level CPU.

At this time, 3% of the CPU’s time was spent executing user-level processes.
The percentage of CPU utilization that occurred while being executed at the user level (application).

%nice (0.00): priority level.

No time was spent on processes with altered priority levels.
The percentage of CPU utilization that occurred while executing at the user level with nice priority was measured.

%system (1.00): system level.

1% of the CPU’s time was spent executing system-level processes.
The percentage of CPU utilization that occurs while executing at the system level (kernel) is measured.

%iowait (0.50): wait time.

0.5% of the CPU’s time was spent waiting for I/O operations to complete.
The percentage of time during which the system had an outstanding disk I/O request while the CPU or CPUs were idle.

%steal (0.00): steal time.

No time was stolen by the hypervisor.
The percentage of time the CPU was idle while waiting for hypervisor operations

%idle (95.50): System idle process.

95.5% of the CPU’s time was idle, indicating low CPU usage at that moment.
The percentage of time that the CPU or CPUs were idle and the system did not have an outstanding disk I/O request was observed.

Average:

The average values of all the collected data points during the period of the sar run.