Operation Manual
bo
Number of blocks per second sent to a block device (e.g. a disk write). Note that
swapping also impacts the values shown here.
in
Interrupts per second. A high value indicates a high I/O level (network and/or disk).
cs
Number of context switches per second. Simplied this means that the kernel has
to replace executable code of one program in memory with that of another program.
us
Percentage of CPU usage from user processes.
sy
Percentage of CPU usage from system processes.
id
Percentage of CPU time spent idling. If this value is zero over a longer period of
time, your CPU(s) are working to full capacity. This is not necessarily a bad
sign—rather refer to the values in columns r and b to determine if your machine
is equipped with sufcient CPU power.
wa
Time spent waiting for IO. If this value is signicantly higher than zero over a
longer period of time, there is a bottleneck in the I/O system (network or hard disk).
st
Percentage of CPU time used by virtual machines.
See vmstat --help for more options.
13.1.2 System Activity Information: sar and
sadc
sar can generate extensive reports on almost all important system activities, among
them CPU, memory, IRQ usage, IO, or networking. It can either generate reports on
the y or query existing reports gathered by the system activity data collector (sadc).
sar and sadc both gather all their data from the /proc le system.
176 Reference