How do I find out Linux Resource utilization to detect system bottlenecks?

vmstat command reports information about processes, memory, paging, block IO, traps, and cpu activity. However, a real advantage of vmstat command output – is to the point and (concise) easy to read/understand. The output of vmstat command use to help identify system bottlenecks. Please note that Linux vmstat does not count itself as a running process.

Here is an output of vmstat command from my enterprise grade system:

$ vmstat -S M

Output:

procs ———–memory———- —swap– —–io—- –system– —–cpu——
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
2  1      0    163    127   1395    0    0  1724  1581   37   42 18 10 48 24  0

Where,

* The fist line is nothing but six different categories. The second line gives more information about each category. This second line gives all data you need.
* -S M: vmstat lets you choose units (k, K, m, M) default is K (1024 bytes) in the default mode. I am using M since this system has  4 GB memory. Without -M option it will use K as unit

Field Description For Vm Mode

(a) procs is the process-related fields are:

* r: The number of processes waiting for run time.
* b: The number of processes in uninterruptible sleep.

(b) memory is the memory-related fields are:

* swpd: the amount of virtual memory used.
* free: the amount of idle memory.
* buff: the amount of memory used as buffers.
* cache: the amount of memory used as cache.

(c) swap is swap-related fields are:

* si: Amount of memory swapped in from disk (/s).
* so: Amount of memory swapped to disk (/s).

(d) io is the I/O-related fields are:

* bi: Blocks received from a block device (blocks/s).
* bo: Blocks sent to a block device (blocks/s).

(e) system is the system-related fields are:

* in: The number of interrupts per second, including the clock.
* cs: The number of context switches per second.

(f) cpu is the CPU-related fields are:

These are percentages of total CPU time.

* us: Time spent running non-kernel code. (user time, including nice time)
* sy: Time spent running kernel code. (system time)
* id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
* wa: Time spent waiting for IO. Prior to Linux 2.5.41, shown as zero.