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The main content of this article is "how to monitor the performance of Linux in detail". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to monitor the performance of Linux in detail.

This is part of our ongoing series of Linux commands and performance monitoring. Both the vmstat and iostat commands apply to all major unix-like systems (Linux/unix/FreeBSD/Solaris).

If the vmstat and iostat commands are not available on your system, install the sysstat package. The vmstat,sar and iostat commands are included in the sysstat (system Monitoring tool) package. The iostat command generates statistics for CPU and all devices. You can download the source code package to compile and install sysstat from this connection, but we recommend that you install it through the YUM command.

Install sysstat on a Linux system

The code is as follows:

# yum-y install sysstat

Vmstat-brief information about memory, processes, paging, etc.

Iostat-CPU statistics, input / output statistics for devices and partitions.

Six examples of vmstat commands under Linux

1. List active and inactive memory

Output six columns in the following example. The meaning of each column parsed in the man page of vmstat. The most important are the free properties in memory and the si and so properties in the swap partition.

The code is as follows:

[root@tecmint] # vmstat-a

Procs-memory--swap---io-----system---cpu-

R b swpd free inact active si so bi bo in cs us sy id wa st

10 0 810420 97380 70628 0 0 115 4 89 79 1 6 90 3 0

Free-Free memory space

Si-the amount of data swapped into memory from disk (in KB) per second.

So-the amount of data, in KB, swapped out of memory per second.

Note: if you execute the vmstat command without arguments, it will output a summary report since the system was started.

two。 Execute vmstat every X seconds for N times

The following command will execute vmstat every 2 seconds, and then automatically stop execution after 6 times.

The code is as follows:

[root@tecmint ~] # vmstat 2 6

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 0 810420 22064 101368 0 0 56 3 50 57 0 3 95 20

00 0 810412 22064 101368 00 00 16 35 00 100 00

00 0 810412 22064 101368 00 00 14 35 00 100 00

00 0 810412 22064 101368 00 00 17 38 00 100 00

00 0 810412 22064 101368 00 00 17 35 00 100 00

00 0 810412 22064 101368 00 00 18 36 01 100 00

3. Vmstat command with timestamp

Execute the vmstat command with the-t argument, which will be followed by a timestamp on each line of output, as shown below.

The code is as follows:

[tecmint@tecmint] $vmstat-t 1 5

Procs-memory- swap---io---- system---cpu- timestamp

R b swpd free buff cache si so bi bo in cs us sy id wa st

0 632028 24992 192244 0 0 70 5 55 78 1 3 95 1 0 2012-09-02 14:57:18 IST

1 0 632028 24992 192244 0 000 171 514 1 594 0 2012-09-02 14:57:19 IST

1 00 631904 24992 192244 00 00 195 600 0 5 95 00 2012-09-02 14:57:20 IST

0 631780 24992 192244 0 000 156 524 0 5 95 00 2012-09-02 14:57:21 IST

1 0 631656 24992 192244 000 0 189 5920 5 95 631656 2012-09-02 14:57:22 IST

4. Count all kinds of counters

The-s argument of the vmstat command outputs statistics for various event counters and memory.

The code is as follows:

[tecmint@tecmint] $vmstat-s

1030800 total memory

524656 used memory

277784 active memory

185920 inactive memory

506144 free memory

26864 buffer memory

310104 swap cache

2064376 total swap

0 used swap

2064376 free swap

4539 non-nice user cpu ticks

0 nice user cpu ticks

11569 system cpu ticks

329608 idle cpu ticks

5012 IO-wait cpu ticks

79 IRQ cpu ticks

74 softirq cpu ticks

0 stolen cpu ticks

336038 pages paged in

67945 pages paged out

0 pages swapped in

0 pages swapped out

258526 interrupts

392439 CPU context switches

1346574857 boot time

2309 forks

5. Disk statistics

The-d parameter of vmstat will output statistics for all disks.

The code is as follows:

[tecmint@tecmint] $vmstat-d

Disk--reads--writes--IO-

Total merged sectors ms total merged sectors ms cur sec

Ram0 0 0 0

Ram1 0 0 0

Ram2 0 0 0

Ram3 0 0 0

Ram4 0 0 0

Ram5 0 0 0

Ram6 0 0 0

Ram7 0 0 0

Ram8 0 0 0

Ram9 0 0 0

Ram10 0 0 0

Ram11 0 0 0

Ram12 0 0 0

Ram13 0 0 0

Ram14 0 0 0

Ram15 0 0 0

Loop0 0 0 0

Loop1 0 0 0

Loop2 0 0 0

Loop3 0 0 0

Loop4 0 0 0

Loop5 0 0 0

Loop6 0 0 0

Loop7 0 0 0

Sr0 0 0 0

Sda 7712 5145 668732 409619 3282 28884 257402 644566 0 126

Dm-0 11578 0 659242 1113017 32163 0 257384 8460026 0 126

Dm-1 324 0 2592 3845 0 0 0 2

6. Output statistics in units of MB

The-S and-M parameters (uppercase and MB) of vmstat will be output in MB. Vmstat outputs statistics in units of KB by default.

The code is as follows:

[root@tecmint] # vmstat-S M 1 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 0 346 53 476 0 0 95 8 42 55 0 2 96 2 0

00 0 346 53 476 00 00 12 15 00 100 00

00 0 346 53 476 00 00 32 62 00 100 00

00 0 346 53 476 00 00 15 13 00 100 00

0 0 0 346 53 476 0 0 0 34 61 0 1 99 0 0

Six examples of Iostat commands under linux

1. Output CPU and input / output statistics

The iostat command with no parameters will output CPU and output / output statistics for each partition, as shown below.

The code is as follows:

[root@tecmint ~] # iostat

Linux 2.6.32-279.el6.i686 (tecmint.com) 09max 03max 2012 _ i6861CPU)

Avg-cpu:% user nice% system% iowait% steal% idle

0.12 0.01 1.54 2.08 0.00 96.24

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn

Sda 3.59 161.02 13.48 1086002 90882

Dm-0 5.76 159.71 13.47 1077154 90864

Dm-1 0.05 0.38 0.00 2576 0

two。 Only output statistics for CPU

The-c argument of the iostat command outputs only the statistics for CPU, as shown below.

The code is as follows:

[root@tecmint] # iostat-c

Linux 2.6.32-279.el6.i686 (tecmint.com) 09max 03max 2012 _ i6861CPU)

Avg-cpu:% user nice% system% iowait% steal% idle

0.12 0.01 1.47 1.98 0.00 96.42

3. Output only disk input / output statistics

The-d parameter of the iostat command outputs only the input / output statistics for all partitions of the disk, as shown below.

The code is as follows:

[root@tecmint ~] # iostat-d

Linux 2.6.32-279.el6.i686 (tecmint.com) 09max 03max 2012 _ i6861CPU)

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn

Sda 3.35 149.81 12.66 1086002 91746

Dm-0 5.37 148.59 12.65 1077154 91728

Dm-1 0.04 0.36 0.00 2576 0

4. Output only the input / output statistics of a disk

By default, the iostat command outputs statistics for all partitions, but if you add the-p parameter and disk device name to the iostat command, the command will output only the input / output statistics for the listed disks, as shown below.

The code is as follows:

[root@tecmint] # iostat-p sda

Linux 2.6.32-279.el6.i686 (tecmint.com) 09max 03max 2012 _ i6861CPU)

Avg-cpu:% user nice% system% iowait% steal% idle

0.11 0.01 1.44 1.92 0.00 96.52

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn

Sda 3.32 148.52 12.55 1086002 91770

Sda1 0.07 0.56 0.00 4120 18

Sda2 3.22 147.79 12.55 1080650 91752

5. Output Statistics for logical Volume Management (LVM)

The-N (uppercase) parameter of the iostat command outputs LVM statistics, as shown below. LVM is a mechanism for managing disk partitions in the linux environment, which is a logical layer between disk partitions and the file system.

The code is as follows:

[root@tecmint] # iostat-N

Linux 2.6.32-279.el6.i686 (tecmint.com) 09max 03max 2012 _ i6861CPU)

Avg-cpu:% user nice% system% iowait% steal% idle

0.11 0.01 1.39 1.85 0.00 96.64

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn

Sda 3.20 142.84 12.16 1086002 92466

Vg_tecmint-lv_root 5.13 141.68 12.16 1077154 92448

Vg_tecmint-lv_swap 0.04 0.34 0.00 2576 0

6. Iostat version information

The-V (uppercase) parameter of iostat will output the version information of iostat, as shown below.

The code is as follows:

[root@tecmint] # iostat-V

Sysstat version 9.0.4

(C) Sebastien Godard (sysstat orange.fr)

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