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This article mainly introduces Docker how to achieve CPU resource restrictions, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

One: description

Windows system usage

-- cpu-period int limits the cycle of CPU CFS, ranging from 100ms~1s, i.e. [1000, 1000000]

-- cpu-quota int limits CPU CFS quota, which must be no less than 1ms, that is, > = 1000

-c,-- cpu-shares int CPU shared weights (relative weights)

-- CPU set allowed by cpuset-cpus string. The value can be 0-3, 0, 0, 0, 1.

-- cpuset-mems string is only valid for NUMA systems

Three: command description

1. By default, all containers get an equal proportion of CPU cycles. When there are multiple containers competing for CPU, we can set the percentage of CPU time that each container can use. This ratio is called shared weight and is set by-c or-- cpu-shares. Docker defaults to a weight of 1024 per container. If you do not set it or set it to 0, this default value will be used. The system allocates CPU time to containers according to the shared weights of each container and the shared weights and proportions of all containers.

Suppose you have three containers that are running, and the tasks in all three containers are CPU-intensive. The cpu share weight of the first container is 1024, and the cpu share weight of the other two containers is 512. The first container will get 50% CPU time, while the other two containers will each get 25% CPU time. If you add a fourth container with a cpu share value of 1024, the CPU time for each container will be recalculated. The CPU time of the first container is 33%, and the CPU time of other containers is 16.5%, 16.5% and 33%, respectively.

It is important to note that this ratio is only useful when performing CPU-intensive tasks. On a quad-core system, assume that there are four single-process containers that can each use 100% CPU time of one core, regardless of their cpu shared weights.

On multi-core systems, CPU time weights are calculated on all CPU cores. Even if the CPU time limit of a container is less than 100%, it can use 100% of the time of each CPU core.

2.docker provides two parameters-cpu-period and-cpu-quota to control the CPU clock cycle to which the container can be allocated. -cpu-period is used to specify how often the container redistributes the use of CPU, while-cpu-quota is used to specify the maximum amount of time that can be spent running the container during this period. Unlike-cpu-shares, this configuration specifies an absolute value, and there is no flexibility in it, so the container's use of CPU resources will never exceed the configured value.

Cpu-period and cpu-quota are in microseconds (μ s). The minimum value of cpu-period is 1000 microseconds, the maximum is 1 second (10 ^ 6 μ s), and the default value is 0.1 second (100000 μ s). The default value of cpu-quota is-1, which means that there is no control.

For example, if the container process needs to use a single CPU for 0.2 seconds every second, you can set cpu-period to 1000000 (that is, 1 second) and cpu-quota to 200000 (0.2 seconds). Of course, in a multicore case, if you allow the container process to fully occupy two CPU, you can set cpu-period to 100000 (that is, 0.1s) and cpu-quota to 200000 (0.2s)

Four: testing

The agileek/cpuset-test image is an image used to test CPU, and its function is to fill up the specified CPU resources.

Docker pull agileek/cpuset-test

1. Docker run-it-- cpuset-cpus= "1pm 3" agileek/cpuset / bin/bash

Indicates that processes in the container can be executed on cpu 1 and cpu 3

2. Docker run-it-cpuset-cpus= "0-2" agileek/cpuset / bin/bash

Indicates that processes in the container can be executed on cpu 1 CPU 2 CPU 3

3. Docker run-ti-rm-name mytest-c 1024 agileek/cpuset-test

Open a new port to monitor container CPU usage

Mpstat-P ALL 5 10

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