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)

 

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