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.
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 over 4 GB memory. Without -M option it will use K as unit
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