This post introduces basic commands for measuring the performance of a server.
Table of Contents
Performance measurement
CPU
The CPU usage can be measured by using the top command.
1
$ top
Memory
The memory usage can be measured by using the free command.
1
$ free -m
When you run the “free” command, the following output is displayed.
1
2
3
total used free shared buff/cache available
Mem: 1999 100 1798 0 100 1898
Swap: 2047 0 2047
The following is the description of each column.
- total: The total amount of memory.
- used: The amount of memory that is used.
- free: The amount of memory that is free.
- shared: The amount of memory that is shared.
- buff/cache: The amount of memory that is used as a buffer or cache.
- available: The amount of memory that is available without swapping.
Basically, the total amount of memory that the process can use is the sum of the “free”, “buff/cache”, and “available” columns.
Disk
The disk usage can be measured by using the df command.
1
$ df -h
When you run the “df” command, the following output is displayed.
1
2
3
4
5
6
7
8
9
10
11
Filesystem Size Used Avail Use% Mounted on
udev 7.8G 0 7.8G 0% /dev
tmpfs 1.6G 1.3M 1.6G 1% /run
/dev/sda1 20G 3.3G 16G 18% /
tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup
/dev/loop0 56M 56M 0 100% /snap/core/7270
/dev/loop1 56M 56M 0 100% /snap/core/7396
/dev/loop2 56M 56M 0 100% /snap/core/7917
...
The following is the description of each column.
- Filesystem: The name of the file system.
- Size: The total size of the file system.
- Used: The amount of the file system that is used.
- Avail: The amount of the file system that is available.
- Use%: The percentage of the file system that is used.
- Mounted on: The mount point of the file system.
Network
The network usage can be measured by using the iftop command.
1
$ iftop
Performance measurement of a backend server
wrk
The wrk command is a HTTP benchmarking tool.
1
2
3
4
5
6
7
8
9
10
# assume that the backend server is located at localhost with 8080 port
# generate 400 HTTP connections with 12 threads for 5 seconds
$ wrk -t 12 -c 400 -d 5 http://localhost:8080
# generate 10 HTTP connections for 5 seconds
$ wrk -c 10 -d 5 http://localhost:8080
# generate 10 HTTP connections for 5 seconds with detailed latency statistics
$ wrk -c 10 -d 5 --latency http://localhost:8080
The following is the description of each option.
- -t: The number of threads.
- -c: The number of connections.
- -d: The duration of the test.
- –latency: Measure latency with more detailed statistics.
wrk2
The wrk2 command is a HTTP benchmarking tool.
1
2
3
4
5
6
7
8
9
10
# assume that the backend server is located at localhost with 8080 port
# generate 400 HTTP connections with 12 threads for 5 seconds
$ wrk2 -t 12 -c 400 -d 5 http://localhost:8080
# generate 10 HTTP connections for 5 seconds
$ wrk2 -c 10 -d 5 http://localhost:8080
# generate 10 HTTP connections for 5 seconds with detailed latency statistics
$ wrk2 -c 10 -d 5 --latency http://localhost:8080
The following is the description of each option.
- -t: The number of threads.
- -c: The number of connections.
- -d: The duration of the test.
- –latency: Measure latency with more detailed statistics.