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This article shows you what performance testing commands are available in Linux, which are concise and easy to understand, which can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

1. Uptime$ uptime 23:51:26 up 21:31, 1 user, load average: 30.02, 26.43, 19.0212

This command can roughly see the overall load of the computer, and the numbers after load average represent the average load of the computer in 1min, 5min and 15min, respectively.

2. Dmesg | tail$ dmesg | tail [1880957.563150] perl invoked oom-killer: gfp_mask=0x280da, order=0, oom_score_adj=0 [...] [1880957.563400] Out of memory: Kill process 18694 (perl) score 246 or sacrifice child [1880957.563408] Killed process 18694 (perl) total-vm:1972392kB, anon-rss:1953348kB, file-rss:0kB [2320864.954447] TCP: Possible SYN flooding on port 7001. Dropping request. Check SNMP counters.123456

Print the contents of the kernel ring cache, which can be used to view some errors

In the above example, process 18694 is dropped by kill and TCP request is discarded because memory is out of bounds. Through dmesg, you can quickly determine whether there are any problems that lead to abnormal system performance.

3. Vmstat 1$ vmstat 1 procs-memory- swap---io-----system---cpu- r b swpd free buff cache si so bi bo in cs us sy id wa st 34 00 200889792 73708 591828 00 0 5 6 10 96 1 3 00 32 00 200889920 73708 591860 00 0592 13284 4282 98 11 00 32 00 200890112 73708 591860 00 00 9501 2154 99 1 00 0 32 00 200889568 73712 591856 00 0 48 11900 2459 99 00 32 00 200890208 73712 591860 00 15898 4840 98 11 00 ^ C123456789

Print statistics for processes, memory, swap partitions, IO, CPU, etc.

The format of vmstat is as follows

> vmstat [options] [delay [count]]

The secondary output of vmstat*** represents the average value from boot to vmstat runtime. The rest output is the average value within the specified time interval. In the above example, the value of delay is set to 1. Except for * times, the rest is counted once a second. If count is not set, it will be printed in a loop.

$vmstat 10 3 procs-memory- swap---io-----system---cpu- r b swpd free buff cache si so bi bo in cs us sy id wa st 100 2527112 1086888 13720228 0 0 1 14 2 11 1 99 2527112 0 2527156 1086888 13719856 00 0 104 3003 4901 00 990 00 00 2526412 1086888 13719904 00 0 10 3345 4870 01 990 0123456

In the above example, delay is set to 10 and the count is set to 3, which means that each line is printed for an average of 10 seconds, only 3 times.

Columns to be checked

R: indicates the number of processes running or waiting for CPU scheduling. Because this column of data does not contain statistics for Ibank O, it can be used to detect whether the CPU is saturated. If the number in the r column is greater than the core number of the CPU, it means that the CPU has been saturated.

Free: current remaining memory

Si, so: the number of swap partitions swapped in and out. If the number of swapping in and out is greater than 0, there is insufficient memory.

The statistical information of us, sy, id and wa:CPU, which represents user time, system time (kernel), idle, and wait I Zero, respectively. The time it takes to process system time O is included in the system time, so if the system time exceeds 20%, there may be bottlenecks or anomalies in it.

4. Mpstat-P ALL 1$ mpstat-P ALL Linux 3.10.0-229.el7.x86_64 (localhost.localdomain) 05Compact 2018 _ x86mm 6416 CPU 04:03:55 PM CPU% usr% sys% iowait% irq% soft% steal% guest% gnice% idle 04:03:55 PM all 3.67 0.00 0.61 0.71 0.00 0.00 0.00 0.00 95.02 04:03:55 PM 0 3.52 0.00 0.57 0.76 0.00 0.00 0.00 95.15 04:03:55 PM 1 3.83 0.00 0.61 0.71 0.00 0.00 0.00 94.85 04:03:55 PM 2 3.80 0.00 0.61 0.60 0.00 0.00 0.00 94.99 04:03:55 PM 3 3.68 0.00 0.58 0.60 0.00 0.00 0.00 95.13 04:03:55 PM 4 3.54 0.00 0.57 0.60 0.00 0.00 0.00 0.00 0.00 95.30 [...] 1234567891011

This command is used to print statistics for each CPU once a second and can be used to see if the scheduling of the CPU is uniform.

5. Pidstat 1$ pidstat 1 Linux 3.13.0-49-generic (titanclusters-xxxxx) 07 rcuos/0 07:41:02 PM UID PID% usr% system% guest% CPU CPU Command 07:41:03 PM 0 9 0.00 0.94 0.94 1 rcuos/0 07:41:03 PM 0 4214 5. 66 5.66 0.00 11.32 15 mesos-slave 07:41:03 PM 0 4354 0.94 0.94 0.00 1.89 8 java 07:41:03 PM 0 6521 1596.23 1.89 0.00 1598.11 27 java 07:41:03 PM 0 6564 1571.70 7.55 0.00 1579.25 28 java 07:41:03 PM 60004 60154 0 .94 4.72 0.00 5.66 9 pidstat 07:41:03 PM UID PID% usr% system% guest% CPU CPU Command 07:41:04 PM 0 4214 6.00 2.00 8.00 15 mesos-slave 07:41:04 PM 0 6521 1590.00 0.00 1591.00 27 java 07:41:04 PM 0 6564 1573.00 10.00 0.00 1583.00 28 java 07:41:04 PM 108 6718 1.00 0.00 0.00 snmp-pass 07:41:04 PM 60004 60154 1.00 0.00 5.00 9 pidstat ^ C123456789101112131415161718

This command is used to print the CPU usage of each process, similar to what is shown in the top command. The advantage of pidstat is that it scrolls the operation of the process, rather than clearing the screen as top does.

In the above example, the cpu utilization of the two java processes in% CPU reached 1590% and 1573%, respectively, indicating that the java process occupied 16 CPU.

6. Iostat-xz 1

Similar to the vmstat,*** output is the sampling data from the time the system is powered on to the statistics.

$iostat-xz 1 Linux 3.13.0-49-generic (titanclusters-xxxxx) 07 iowait 14 CPU avg-cpu:% user% nice% system% iowait% steal% idle 73.96 0.00 3.73 0.03 0.06 22.21 Device: rrqm/s wrqm/s Randall s rkB/s wkB/s avgrq-sz avgqu- Sz await r_await w_await svctm% util xvda 0.00 0.23 0.21 0.18 4.52 2.08 34.37 0.00 9.98 13.80 5.42 2.44 0.09 xvdb 1.02 8.94 127.97 598.53 0.00 0.43 1.78 0. 28 0.25 0.25 xvdc 0.01 0.00 1.02 8.86 127.79 595.94 146.50 0.00 0.45 1.82 0.30 0.27 0.26 dm-0 0.00 0.00 0.69 2.32 10.47 31.69 28.01 0.01 3.23 0.71 3.98 0. 13 0.04 dm-1 0.00 0.00 0.00 0.94 0.01 3.78 8.00 0.33 345.84 0.04 346.81 0.01 0.00 dm-2 0.00 0.00 0.09 0.07 1.35 0.36 22.50 0.00 2.55 0.23 5.62 1 .78 0.03 [.] ^ C123456789101112131415 check column

The number of reads, writes, read Kbytes, and write Kbytes sent to the reads O device per second is indicated by r _ hand s, w _ hand s, rkB/s, wkB/s.

Await, which represents the average Imax O time that the application was queued and serviced. If this value is greater than the expected time, it indicates that the IActionO device is saturated or abnormal.

Avgqu-sz, which represents the average time that the request was sent to the Igamot device. If the value is greater than 1, the Icano device may be saturated.

% util, the utilization rate of the device per second; if the utilization rate exceeds 60%, the device has abnormal performance

7. Free-m $free-m total used free shared buffers cached Mem: 245998 24545 221453 83 59 541-/ + buffers/cache: 23944 222053 Swap: 0 012345

Columns checked:

Buffers: For the buffer cache, used for block device I/O. Cached: For the page cache, used by file systems.

If buffers and cached are close to 0, it means that the utilization rate of Icano is too high, and there are performance problems in the system.

Free memory is used as cache in Linux. If the application needs to allocate memory, the system can quickly reclaim the memory occupied by cache, so the memory of free contains the part occupied by cache.

8. Sar-n DEV 1

Sar is an acronym for System Activity Reporter, system activity status report.

-n {keyword [,...] | ALL}, used to report network statistics. Keyword can be one or more of the following: DEV, EDEV, NFS, NFSD, SOCK, IP, EIP, ICMP, EICMP, TCP, ETCP, UDP, SOCK6, IP6, EIP6, ICMP6, EICMP6 and UDP6.

-n DEV 1 to count the usage of the network every second

-n EDEV 1, count the wrong network information every second

$sar-n DEV 1 Linux 3.10.0-229.el7.x86_64 (localhost.localdomain) 05 take 31 CPU) 03:54:57 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s 03:54:58 PM ens32 3286.00 7207.00 283.34 18333.90 0.00 0.00 03:54:58 PM lo 0.00 0.00 0.00 03:54:58 PM vethe915e51 0.00 0.00 0.00 03:54:58 PM docker0 0.00 0.00 0.00 0.00 0.00 03:54:58 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s 03:54:59 PM ens32 3304.00 7362.00 276.89 18898.51 0.00 0.00 0.00 03:54:59 PM lo 0.00 0.00 0.00 0. 00 0.00 0.00 03:54:59 PM vethe915e51 0.00 0.00 0.00 03:54:59 PM docker0 0.00 0.00 0.00 ^ C123456789101112131415

IFACE, network interface name

Rxpck/s, packets received per second

Txpck/s, the number of messages transmitted per second; (transmit packages)

RxkB/s, kilobytes received per second

TxkB/s, kilobytes sent per second

Rxcmp/s, the number of compressed packets received per second

Txcmp/s, the number of compressed packets sent per second

Rxmcst/s, the number of group packets received per second

9. Sar-n TCP,ETCP 1

This command can be used to roughly determine the throughput of the network, such as the number of network connections initiated and the number of network connections received

TCP, reporting statistics on TCPv4 network traffic

ETCP, reporting statistics about TCPv4 network errors

$sar-n TCP ETCP 1 Linux 3.10.0-514.26.2.el7.x86_64 (aushop) 05 PM 2018 _ x86 Linux 642 CPU 04:16:27 PM active/s passive/s iseg/s oseg/s 04:16:44 PM 0.00 2.00 15.00 13.00 04:16:45 PM 0.00 126.00 203.00 04:16:46 PM 0.00 0.00 99.00 99.00 04:16:47 PM 0.00 0.00 18.00 9.00 04:16:48 PM 0.00 0.00 5.00 6.00 04:16:49 PM 0.00 0.00 1.00 1.00 04:16:50 PM 0.00 1.00 4.00 4 .00 04:16:51 PM 0.00 3.00 171.00 243.00 ^ C12345678910111213

Detected columns:

Active/s: Number of locally-initiated TCP connections per second (e.g., via connect ()), the number of network connections initiated

Passive/s: Number of remotely-initiated TCP connections per second (e.g., via accept ()), the number of network connections received

Retrans/s: Number of TCP retransmits per second, number of retransmissions

10. Top

The top command contains more metric statistics, which is equivalent to a comprehensive command.

Top top-00:15:40 up 21:56, 1 user, load average: 31.09,29.87,29.92 Tasks: 871 total, 1 running, 868 sleeping, 0 stopped, 2 zombie% Cpu (s): 96.8 us, 0.4 sy, 0.0 ni, 2.7 id, 0.1 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 25190241+total, 24921688 used, 22698073+free, 60448 buffers KiB Swap: 0 total 0 used, 0 free. 554208 cached Mem PID USER PR NI VIRT RES SHR S% CPU% MEM TIME+ COMMAND 20248 root 20 0 0.227t 0.012t 18748 S 3090 5.229812 java 4213 root 20 2722544 64640 44232 S 23.5 233R1.00.0 mesos-slave 66128 titancl+ 20 024344 2332 1172 R 1.0 0.07 top 5235 root 20 0 38.227g 54700449996 S 0 . 7 0.2 2:02.74 java 4299 root 20 0 20.015g 2.682g 16836 S 0.3 1.1 33:14.42 java 1 root 20 0 33620 2920 1496 S 0.0 0.0 0:03.82 init 2 root 20 00 00 S 0.0 0.0 0:00.02 kthreadd 3 root 20 0 00 S 0.0 0.00: 05.35 ksoftirqd/0 5 root 0-20 000 S 0.0 0.00: 00.00 kworker/0:0H 6 root 20 00 S 0.0 0.00: 06.94 kworker/u256:0 8 root 20 00 0 0 S 0.0 0.0 2:38.05 rcu_sched1234567891011121314151617181911. Summary

The following picture shows the main functions of various commands, such as using vmstat to view the overall performance of the system, mpstat to view the performance of cpu, pidstat to view the status of processes, iostat to view the status of io, free to view the status of memory, sar to view the status of the network, and so on.

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An overview of common performance tools for Linux

What are the performance testing commands in Linux? have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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