Using Vmstat for Profiling

Taken from RHEL Performance Tuning Student Booklet The vmstat command, if given no arguments, will print out the averages of various system statistics since boot. The vmstat command accepts two arguments. The first is the delay, and the second is the count. The delay is a value in seconds between output. The count is the number of iterations of statistics to report.

[root@lime ~]# vmstat 4 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
0  0   2832 145216 194528 6772048    0    0     0     1    0    1  0  0 100  0  0
0  0   2832 145200 194528 6772048    0    0     0     1   44   45  0  0 100  0  0
0  0   2832 145208 194528 6772048    0    0     0     8   46   45  0  0 100  0  0
1  0   2832 145208 194528 6772048    0    0     0     0   44   46  0  0 100  0  0
0  0   2832 145208 194528 6772048    0    0     0     3   46   55  0  0 100  0  0

Category	Statistics	Definition
Process related	r	The number of processes waiting for runtime
Process related	b	The number of processes in uninterruptible sleep
memory	swpd	The amount of memory currently used in swap spaces
memory	free	The amount of idle (immediately available) memory
memory	buff	The amount of memory used as buffers
memory	cache	The amount of memory used as cache
swap: paging statistics	si	Pages of memory swapped in per second
swap: paging statistics	so	Pages of memory swapped out per second
io: block I/O statistics	bi	Blocks per second received from block devices
io: block I/O statistics	bo	Blocks per second sent to block devices
system	in	Interrupts raised per second
system	cs	Context switches per second
cpu: how CPU time is used	us	Percentage of time spent running user-space code
cpu: how CPU time is used	sy	Percentage of time spent running kernel code
cpu: how CPU time is used	id	Percentage of time spent idle
cpu: how CPU time is used	wa	Percentage of time spent blocked while waiting for I/O to complete
cpu: how CPU time is used	st	Percentage of time where the CPU had a process ready to run, but CPU time was stolen by the hypervisor supporting this virtual machine (typically because the CPU is being used by another guest virtual machine)