Linux sar command usage and code example analysis

1. CPU utilization

sar -p (view all day)
sar -u 1 10 (1: every second, 10: write 10 times)

1.1. CPU output item description

Output	Detailed description
CPU	all means that the statistics are the average of all CPUs.
%user	Shows the percentage of total CPU time used by applications running at the user level.
%nice	Shows the percentage of total CPU time spent on nice operations at the user level.
%system	The percentage of total CPU time spent running at the kernel level.
%iowait	Shows the percentage of total CPU time spent waiting for I/O operations.
%steal	The percentage of virtual CPUs that the hypervisor was waiting to service another virtual process.
%idle	Displays the percentage of CPU idle time to total CPU time.

2. Memory Utilization

sar -r (view all day)
sar -r 1 10 (1: every second, 10: write 10 times)

2.1. Memory output item description

Output	Detailed description
kbmemfree	This value is basically the same as the free value in the free command, so it does not include the buffer and cache space.
kbmemused	This value is basically the same as the used value in the free command, so it includes the buffer and cache space.
%memused	This value is a percentage of kbmemused and the total memory (excluding swap).
kbbuffers and kbcached	These two values are buffer and cache in the free command.
kbcommit	Ensure the memory required by the current system, that is, the memory required to ensure no overflow (RAM + swap).
%commit	This value is a percentage of kbcommit and the total amount of memory (including swap).

3. Disk I/O

sar -d (view all day)
sar -d 1 2 (1: every second, 2: write twice)

3.1. IO output item description

Output	Detailed description
await	Indicates the average waiting time (in milliseconds) for each device I/O operation.
svctm	Indicates the average service time (in milliseconds) for each device I/O operation.
%util	Indicates the percentage of time per second that is spent on I/O operations.

4. Network traffic

sar -n DEV (view all day)
sar -n DEV 1 2 (1: every second, 2: write twice)

4.1. DEV output item description

Output	Detailed description
IFACE	This is the name of the network device.
rxpck/s	The number of packets received per second.
txpck/s	The number of packets sent per second.
rxkB/s	The number of bytes received per second.
txkB/s	The number of bytes sent per second.
rxcmp/s	The number of compressed packets received per second.
txcmp/s	The number of compressed packets sent per second.
rxmcst/s	The number of multicast packets received per second.

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