目錄

創(chuàng)建私有倉庫

將修改過的nginx鏡像做標(biāo)記封裝，準(zhǔn)備上傳到私有倉庫

將鏡像上傳到私有倉庫

從私有倉庫中下載鏡像到本地

CPU使用率

CPU共享比例

CPU周期限制

CPU 配額控制參數(shù)的混合案例

內(nèi)存限制

Block IO 的限制

限制bps 和iops

---

創(chuàng)建私有倉庫

倉庫（Repository）是集中存放鏡像的地方。

倉庫注冊(cè)服務(wù)器才是存放倉庫具體的服務(wù)器（Registry），每個(gè)服務(wù)器上都可以放置多個(gè)倉庫，而每個(gè)倉庫下可以放置多個(gè)鏡像，每個(gè)鏡像上可以運(yùn)行多個(gè)容器，每個(gè)容器上可以跑一個(gè)應(yīng)用或應(yīng)用組。

安裝docker后，可以通過官方提供的registry鏡像部署一套本地的私有倉庫環(huán)境

[root@localhost ~]# mkdir -p /opt/data/registry

[root@localhost ~]# docker run -d --restart=always -p 5000:5000 -v /opt/data/registry:/tmp/registry registry

Unable to find image 'registry:latest' locally

Trying to pull repository docker.io/library/registry ...

latest: Pulling from docker.io/library/registry

79e9f2f55bf5: Pull complete

0d96da54f60b: Pull complete

5b27040df4a2: Pull complete

e2ead8259a04: Pull complete

3790aef225b9: Pull complete

Digest: sha256:169211e20e2f2d5d115674681eb79d21a217b296b43374b8e39f97fcf866b375

Status: Downloaded newer image for docker.io/registry:latest

a0edf5ac6cdda7464855c98db855c60f32f54bf8f078647dc2b8357aa8581151

[root@localhost ~]# docker ps -l

CONTAINER ID ???????IMAGE ??????????????COMMAND ?????????????????CREATED ????????????STATUS ?????????????PORTS ???????????????????NAMES

a0edf5ac6cdd ???????registry ???????????"/entrypoint.sh /e..." ??31 seconds ago ?????Up 29 seconds ??????0.0.0.0:5000->5000/tcp ??thirsty_ptolemy

準(zhǔn)備測試鏡像

[root@localhost ~]# docker run -d -p 8000:80 nginx???? //將宿主機(jī)8000端口映射給容器的業(yè)務(wù)端口

ea26add1a77cd25a90041acfd3b0994630cecc098de2ed15f088be9b4fa8335a

[root@localhost ~]# docker ps -l

CONTAINER ID ???????IMAGE ??????????????COMMAND ?????????????????CREATED ????????????STATUS ?????????????PORTS ?????????????????NAMES

ea26add1a77c ???????nginx ??????????????"/docker-entrypoin..." ??9 seconds ago ??????Up 8 seconds ???????0.0.0.0:8000->80/tcp ??nifty_knuth

宿主機(jī)訪問8000端口測試：

[root@localhost ~]# docker logs ?ea26add1a77c

[root@localhost ~]# docker tag nginx 192.168.50.59:5000/nginx-awd

將修改過的nginx鏡像做標(biāo)記封裝，準(zhǔn)備上傳到私有倉庫

[root@localhost ~]# cat /etc/docker/daemon.json

{

????????"registry-mirrors":[ "https://nyakyfun.mirror.aliyuncs.com" ]

}

[root@localhost ~]# vim /etc/docker/daemon.json

{

????????"registry-mirrors":[ "https://nyakyfun.mirror.aliyuncs.com" ],"insecure-registries":["192.168.50.59:5000"]

}

[root@localhost ~]# systemctl daemon-reload

[root@localhost ~]# systemctl restart docker

將鏡像上傳到私有倉庫

[root@localhost ~]# docker push 192.168.50.59:5000/nginx-awd

The push refers to a repository [192.168.50.59:5000/nginx-awd]

d874fd2bc83b: Pushed

32ce5f6a5106: Pushed

f1db227348d0: Pushed

b8d6e692a25e: Pushed

e379e8aedd4d: Pushed

2edcec3590a4: Pushed

latest: digest: sha256:ee89b00528ff4f02f2405e4ee221743ebc3f8e8dd0bfd5c4c20a2fa2aaa7ede3 size: 1570

查看

[root@localhost ~]# docker images

REPOSITORY ????????????????????TAG ????????????????IMAGE ID ???????????CREATED ????????????SIZE

centos ????????????????????????exp ????????????????c85e59d0ca2f ???????23 hours ago ???????231 MB

192.168.50.59:5000/nginx-awd ??latest ?????????????605c77e624dd ???????19 months ago ??????141 MB

刪除掉測試

[root@localhost ~]# docker rmi 192.168.50.59:5000/nginx-awd

Untagged: 192.168.50.59:5000/nginx-awd:latest

Untagged: 192.168.50.59:5000/nginx-awd@sha256:ee89b00528ff4f02f2405e4ee221743ebc3f8e8dd0bfd5c4c20a2fa2aaa7ede3

[root@localhost ~]# docker images

REPOSITORY ??????????TAG ????????????????IMAGE ID ???????????CREATED ????????????SIZE

centos ??????????????exp ????????????????c85e59d0ca2f ???????23 hours ago ???????231 MB

docker.io/nginx ?????latest ?????????????605c77e624dd ???????19 months ago ??????141 MB

docker.io/registry ??latest ?????????????b8604a3fe854 ???????20 months ago ??????26.2 MB

docker.io/centos ????latest ?????????????5d0da3dc9764 ???????22 months ago ??????231 MB

從私有倉庫中下載鏡像到本地

[root@localhost ~]# docker pull 192.168.50.59:5000/nginx-awd

Using default tag: latest

Trying to pull repository 192.168.50.59:5000/nginx-awd ...

latest: Pulling from 192.168.50.59:5000/nginx-awd

Digest: sha256:ee89b00528ff4f02f2405e4ee221743ebc3f8e8dd0bfd5c4c20a2fa2aaa7ede3

Status: Downloaded newer image for 192.168.50.59:5000/nginx-awd:latest

[root@localhost ~]# docker images

REPOSITORY ????????????????????TAG ????????????????IMAGE ID ???????????CREATED ????????????SIZE

centos ????????????????????????exp ????????????????c85e59d0ca2f ???????23 hours ago ???????231 MB

192.168.50.59:5000/nginx-awd ??latest ?????????????605c77e624dd ???????19 months ago ??????141 MB

Docker資源限制

Docker容器技術(shù)底層是通過Cgroup（Control?Group?控制組）實(shí)現(xiàn)容器對(duì)物理資源使用的限制，限制的資源包括CPU、內(nèi)存、磁盤三個(gè)方面。基本覆蓋了常見的資源配額和使用量控制。

Cgroup?是Linux 內(nèi)核提供的一種可以限制、記錄、隔離進(jìn)程組所使用的物理資源的機(jī)制，被LXC及Docker等很多項(xiàng)目用于實(shí)現(xiàn)進(jìn)程的資源控制。

Cgroup 是提供將進(jìn)程進(jìn)行分組化管理的功能和接口的基礎(chǔ)結(jié)構(gòu)，Docker中I/O 或內(nèi)存的分配控制等具體的資源管理功能都是通過Cgroup功能來實(shí)現(xiàn)的。這些具體的資源管理功能稱為Cgroup子系統(tǒng)

使用下面的Dockerfile 來創(chuàng)建一個(gè)基于CentOS的stress工具鏡像。

[root@localhost ~]# cat centos-7-x86_64.tar.gz | docker import - centos:7

sha256:6e593ec2c4f80e5d44cd15d978c59c701f02b72b1c7458778854a6dc24d492b8

[root@localhost ~]# mkdir stress

[root@localhost ~]# vim stress/Dockerfile

FROM centos:7

MAINTAINER crushlinux "crushlinux@163.com"

RUN yum -y install wget

RUN wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

RUN yum -y install stress

~ ????????

[root@localhost ~]# cd stress/

[root@localhost stress]# docker build -t centos:stress .

CPU使用率

[root@localhost stress]# ?docker run -itd centos:stress /bin/bash

9d9428089027bf70bf2b4e6a441cab0d465c2f5dd3988420b05c7149d4a9ff3d

????????????????

utes ago ?????????????????????????????suspicious_franklin

[root@localhost stress]# docker ps -a

CONTAINER ID ???????IMAGE ??????????????COMMAND ?????????????????CREATED ????????????STATUS ???????????????????????PORTS ???????????????????NAMES

9d9428089027 ???????centos:stress ??????"/bin/bash" ?????????????39 seconds ago ?????Up 38 seconds ?????????????????????????????????????????silly_mestorf

[root@localhost stress]# vim /sys/fs/cgroup/cpu,cpuacct/cpu.cfs_quota_us

-1

CPU共享比例

當(dāng)多個(gè)容器任務(wù)運(yùn)行時(shí)，很難計(jì)算CPU的使用率，為了使容器合理使用CPU資源，可以通過--cpu-shares選項(xiàng)設(shè)置容器按比例共享CPU資源，這種方式還可以實(shí)現(xiàn)CPU使用率的動(dòng)態(tài)調(diào)整。

命令中的--cpu-shares 選項(xiàng)值不能保證可以獲得1 個(gè)vcpu 或者多少GHz 的CPU 資源，僅僅只是一個(gè)彈性的加權(quán)值。

[root@localhost ~]# docker run --name aa -itd --cpu-shares 1024 centos:stress /bin/bash

1c9d6552e940da713e8ce89c9b10f045aff0b1fcbfdef45f2f9bf1d2189c4604

[root@localhost ~]# docker run --name bb -itd --cpu-shares 1024 centos:stress /bin/bash

4a7ea87192d16d4b8b086c125a467357f28aed00157726367cefea7fada12a21

[root@localhost ~]# docker run --name cc -itd --cpu-shares 2048 centos:stress /bin/bash

7b52275fa1b3c00b1bcbbb5ef6ef165f4b33bc5ccab51908b66e19b7f50fe772

[root@localhost ~]# docker run --name dd -itd --cpu-shares 4096 centos:stress /bin/bash

b56f55536170be6ac5bf25b6e1350e126c05fc44cf54d954a7c9d679ef73c110

默認(rèn)情況下，每個(gè)docker容器的cpu份額都是1024。單獨(dú)一個(gè)容器的份額是沒有意義的。只有在同時(shí)運(yùn)行多個(gè)容器時(shí)，容器的CPU加權(quán)的效果才能體現(xiàn)出來。例如，兩個(gè)容器A、B的CPU份額分別為1000和500，在CPU進(jìn)行時(shí)間片分配的時(shí)候，容器A比容器B多一倍的機(jī)會(huì)獲得CPU的時(shí)間片。但分配的結(jié)果取決于當(dāng)時(shí)主機(jī)和其他容器的運(yùn)行狀態(tài)，實(shí)際上也無法保證容器A一定能獲得CPU時(shí)間片。比如容器A的進(jìn)程一直是空閑的，那么容器B 是可以獲取比容器A更多的CPU時(shí)間片的。極端情況下，比如說主機(jī)上只運(yùn)行了一個(gè)容器，即使它的CPU份額只有50，它也可以獨(dú)占整個(gè)主機(jī)的CPU資源。

換句話說,可以通過cpu shares可以設(shè)置容器使用CPU的優(yōu)先級(jí)，比如啟動(dòng)了兩個(gè)容器及運(yùn)行查看CPU使用百分比。

[root@localhost ~]# docker run -tid --name cpu1024 --cpu-shares 1024 centos:stress stress -c 10

3aa4978e3257d760b66b8d85a9c78257e982fcff593f4211880a914a59978603

[root@localhost ~]# docker run -tid --name cpu512 --cpu-shares 512 centos:stress stress -c 10

[root@localhost ~]# docker ps -a

CONTAINER ID ???????IMAGE ??????????????COMMAND ????????????CREATED ?????????????STATUS ?????????????PORTS ??????????????NAMES

3aa4978e3257 ???????centos:stress ??????"stress -c 10" ?????About a minute ago ??Up About a minute ??????????????????????cpu1024

8a0048522072 ???????centos:stress ??????"stress -c 10" ?????2 minutes ago ???????Up 2 minutes ???????????????????????????cpu512

[root@localhost ~]# docker exec -it 3a /bin/bash

[root@3aa4978e3257 /]# top

top - 02:46:44 up ?5:45, ?0 users, ?load average: 19.34, 10.07, 4.21

Tasks: ?13 total, ?11 running, ??2 sleeping, ??0 stopped, ??0 zombie

%Cpu(s): 98.6 us, ?1.4 sy, ?0.0 ni, ?0.0 id, ?0.0 wa, ?0.0 hi, ?0.0 si, ?0.0 st

KiB Mem : ?3861056 total, ??846756 free, ??292556 used, ?2721744 buff/cache

KiB Swap: ?2097148 total, ?2097148 free, ???????0 used. ?2961824 avail Mem

???PID USER ?????PR ?NI ???VIRT ???RES ???SHR S %CPU %MEM ????TIME+ COMMAND ??????????????????????????

????11 root ?????20 ??0 ???7260 ????92 ?????0 R ?7.0 ?0.0 ??0:11.83 stress ???????????????????????????

????14 root ?????20 ??0 ???7260 ????92 ?????0 R ?7.0 ?0.0 ??0:11.84 stress ???????????????????????????

?????6 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.7 ?0.0 ??0:11.83 stress ???????????????????????????

?????7 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.7 ?0.0 ??0:11.83 stress ???????????????????????????

?????8 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.7 ?0.0 ??0:11.84 stress ???????????????????????????

?????9 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.7 ?0.0 ??0:11.84 stress ???????????????????????????

????10 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.3 ?0.0 ??0:11.83 stress ???????????????????????????

????12 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.3 ?0.0 ??0:11.82 stress ???????????????????????????

????13 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.3 ?0.0 ??0:11.83 stress ???????????????????????????

????15 root ?????20 ??0 ???7260 ????92 ?????0 R ?6.3 ?0.0 ??0:11.83 stress ???????????????????????????

?????1 root ?????20 ??0 ???7260 ???640 ???548 S ?0.0 ?0.0 ??0:00.01 stress ???????????????????????????

????16 root ?????20 ??0 ??11748 ??1796 ??1444 S ?0.0 ?0.0 ??0:00.01 bash ?????????????????????????????

????31 root ?????20 ??0 ??51872 ??1940 ??1408 R ?0.0 ?0.1 ??0:00.00 top ??????????????????????????????

?開啟了10 個(gè)stress 進(jìn)程，目的是充分讓系統(tǒng)資源變得緊張。只有這樣競爭資源，設(shè)定的資源比例才可以顯現(xiàn)出來。如果只運(yùn)行一個(gè)進(jìn)行，會(huì)自動(dòng)分配到空閑的CPU，這樣比例就無法看出來。由于案例的環(huán)境不一樣，可能導(dǎo)致上面兩張圖中占用CPU 百分比會(huì)不同，但是從cpu share 來看兩個(gè)容器總比例一定會(huì)是1:2。

[root@localhost ~]# docker exec -it 8a /bin/bash

[root@8a0048522072 /]# top

top - 02:47:53 up ?5:47, ?0 users, ?load average: 20.04, 12.21, 5.38

Tasks: ?13 total, ?11 running, ??2 sleeping, ??0 stopped, ??0 zombie

%Cpu(s): 98.2 us, ?1.8 sy, ?0.0 ni, ?0.0 id, ?0.0 wa, ?0.0 hi, ?0.0 si, ?0.0 st

KiB Mem : ?3861056 total, ??846756 free, ??292548 used, ?2721752 buff/cache

KiB Swap: ?2097148 total, ?2097148 free, ???????0 used. ?2961828 avail Mem

???PID USER ?????PR ?NI ???VIRT ???RES ???SHR S %CPU %MEM ????TIME+ COMMAND ??????????????????????????

?????9 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.7 ?0.0 ??0:15.21 stress ???????????????????????????

????12 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.7 ?0.0 ??0:15.21 stress ???????????????????????????

????14 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.7 ?0.0 ??0:15.20 stress ???????????????????????????

?????6 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.3 ?0.0 ??0:15.20 stress ???????????????????????????

?????7 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.3 ?0.0 ??0:15.19 stress ???????????????????????????

????10 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.3 ?0.0 ??0:15.20 stress ???????????????????????????

????13 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.3 ?0.0 ??0:15.19 stress ???????????????????????????

????15 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.3 ?0.0 ??0:15.21 stress ???????????????????????????

?????8 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.0 ?0.0 ??0:15.19 stress ???????????????????????????

????11 root ?????20 ??0 ???7260 ????92 ?????0 R ?3.0 ?0.0 ??0:15.19 stress ???????????????????????????

?????1 root ?????20 ??0 ???7260 ???640 ???548 S ?0.0 ?0.0 ??0:00.01 stress ???????????????????????????

????16 root ?????20 ??0 ??11772 ??1896 ??1500 S ?0.0 ?0.0 ??0:00.01 bash ?????????????????????????????

31 root ?????20 ??0 ??51872 ??1944 ??1408 R ?0.0 ?0.1 ??0:00.00 top ??

CPU周期限制

cpu-period 和cpu-quota 的單位為微秒（μs）。cpu-period 的最小值為1000 微秒，

最大值為1 秒（10^6 μs），默認(rèn)值為0.1 秒（100000 μs）。cpu-quota 的值默認(rèn)為-1，

表示不做控制。cpu-period、cpu-quota 這兩個(gè)參數(shù)一般聯(lián)合使用。

[root@localhost ~]# ?docker run -it --cpu-period 100000 --cpu-quota 200000 centos:stress /bin/bash

??????????[root@67f52c4e2d20 /]# cat /sys/fs/cgroup/cpu/cpu.cfs_period_us

100000

[root@67f52c4e2d20 /]# cat /sys/fs/cgroup/cpu/cpu.cfs_quota_us ?

200000

CPU 配額控制參數(shù)的混合案例

通過--cpuset-cpus 指定容器A 使用CPU 內(nèi)核0，容器B 只是用CPU 內(nèi)核1。在主機(jī)上只有這兩個(gè)容器使用對(duì)應(yīng)CPU 內(nèi)核的情況，它們各自占用全部的內(nèi)核資源，--cpu-shares 沒有明顯效果。

--cpuset-cpus、--cpuset-mems 參數(shù)只在多核、多內(nèi)存節(jié)點(diǎn)上的服務(wù)器上有效，并且必須與實(shí)際的物理配置匹配，否則也無法達(dá)到資源控制的目的。

在系統(tǒng)具有多個(gè)CPU 內(nèi)核的情況下，需要通過cpuset-cpus 為容器CPU 內(nèi)核才能比較方便地進(jìn)行測試。

[root@localhost ~]# docker run -itd --name cpu0 --cpuset-cpus 0 --cpu-shares 512 centos:stress stress -c 1

d3734959ddb9a118d857a5d7d35b426b697b3d6a09670e6041096a74c17b6c4f

[root@localhost ~]# docker ps -a

CONTAINER ID ???????IMAGE ??????????????COMMAND ????????????CREATED ?????????????STATUS ?????????????PORTS ??????????????NAMES

d3734959ddb9 ???????centos:stress ??????"stress -c 1" ??????About a minute ago ??Up 1 second ????????????????????????????cpu0

[root@localhost ~]# docker exec -it d37 /bin/bash

[root@d3734959ddb9 /]# top

top - 06:25:23 up ?3:32, ?0 users, ?load average: 0.42, 0.20, 0.48

Tasks: ??4 total, ??2 running, ??2 sleeping, ??0 stopped, ??0 zombie

%Cpu(s): ?6.3 us, 14.6 sy, ?0.0 ni, 79.1 id, ?0.0 wa, ?0.0 hi, ?0.1 si, ?0.0 st

KiB Mem : ?3861048 total, ??415924 free, ??251640 used, ?3193484 buff/cache

KiB Swap: ?2097148 total, ?2096884 free, ?????264 used. ?2961148 avail Mem

???PID USER ?????PR ?NI ???VIRT ???RES ???SHR S ?%CPU %MEM ????TIME+ COMMAND ?????????????????????????

?????6 root ?????20 ??0 ???7260 ????92 ?????0 R 100.0 ?0.0 ??0:08.09 stress ??????????????????????????

?????1 root ?????20 ??0 ???7260 ???432 ???352 S ??0.0 ?0.0 ??0:00.00 stress ??????????????????????????

?????7 root ?????20 ??0 ??11772 ??1804 ??1444 S ??0.0 ?0.0 ??0:00.01 bash ????????????????????????????

????21 root ?????20 ??0 ??51868 ??1896 ??1388 R ??0.0 ?0.0 ??0:00.00 top ?????????????????????????????

內(nèi)存限制

與操作系統(tǒng)類似，容器可使用的內(nèi)存包括兩部分：物理內(nèi)存和swap。Docker 通過下面兩組參數(shù)來控制容器內(nèi)存的使用量。

1. -m 或--memory：設(shè)置內(nèi)存的使用限額，例如100M, 1024M。
2. --memory-swap：設(shè)置內(nèi)存swap 的使用限額。

3. 當(dāng)執(zhí)行如下命令：

   其含義是允許該容器最多使用200M 的內(nèi)存和300M 的swap。

[root@localhost ~]# ?docker run -it -m 200M --memory-swap=300M progrium/stress --vm 1 --vm-bytes 280M

Unable to find image 'progrium/stress:latest' locally

Trying to pull repository docker.io/progrium/stress ...

latest: Pulling from docker.io/progrium/stress

a3ed95caeb02: Pull complete

871c32dbbb53: Pull complete

dbe7819a64dd: Pull complete

d14088925c6e: Pull complete

58026d51efe4: Pull complete

7d04a4fe1405: Pull complete

1775fca35fb6: Pull complete

5c319e267908: Pull complete

Digest: sha256:e34d56d60f5caae79333cee395aae93b74791d50e3841986420d23c2ee4697bf

Status: Downloaded newer image for docker.io/progrium/stress:latest

stress: info: [1] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd

stress: dbug: [1] using backoff sleep of 3000us

stress: dbug: [1] --> hogvm worker 1 [6] forked

stress: dbug: [6] allocating 293601280 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

stress: dbug: [6] freed 293601280 bytes

stress: dbug: [6] allocating 293601280 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

stress: dbug: [6] freed 293601280 bytes

stress: dbug: [6] allocating 293601280 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

stress: dbug: [6] freed 293601280 bytes

stress: dbug: [6] allocating 293601280 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

stress: dbug: [6] freed 293601280 bytes

stress: dbug: [6] allocating 293601280 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

stress: dbug: [6] freed 293601280 bytes

stress: dbug: [6] allocating 293601280 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

1. --vm 1：啟動(dòng)1 個(gè)內(nèi)存工作線程。
2. --vm-bytes 280M：每個(gè)線程分配280M 內(nèi)存。

默認(rèn)情況下，容器可以使用主機(jī)上的所有空閑內(nèi)存。與CPU 的cgroups 配置類似，docker 會(huì)自動(dòng)為容器在目錄/sys/fs/cgroup/memory/docker/<容器的完整長ID>中創(chuàng)建相應(yīng)cgroup 配置文件。

因?yàn)?80M 在可分配的范圍（300M）內(nèi)，所以工作線程能夠正常工作，其過程是：

1. 分配280M 內(nèi)存。
2. 釋放280M 內(nèi)存。
3. 再分配280M 內(nèi)存。
4. 再釋放280M 內(nèi)存。
5. 一直循環(huán)......

如果讓工作線程分配的內(nèi)存超過300M，分配的內(nèi)存超過限額，stress 線程報(bào)錯(cuò)，容器退出。

[root@localhost ~]# docker run -it -m 200M --memory-swap=300M progrium/stress --vm 1 --vm-bytes 380M

stress: info: [1] dispatching hogs: 0 cpu, 0 io, 1 vm, 0 hdd

stress: dbug: [1] using backoff sleep of 3000us

stress: dbug: [1] --> hogvm worker 1 [6] forked

stress: dbug: [6] allocating 398458880 bytes ...

stress: dbug: [6] touching bytes in strides of 4096 bytes ...

stress: FAIL: [1] (416) <-- worker 6 got signal 9

stress: WARN: [1] (418) now reaping child worker processes

stress: FAIL: [1] (422) kill error: No such process

stress: FAIL: [1] (452) failed run completed in 1s

Block IO 的限制

默認(rèn)情況下，所有容器能平等地讀寫磁盤，可以通過設(shè)置--blkio-weight 參數(shù)來改變?nèi)萜鱞lock IO 的優(yōu)先級(jí)。

--blkio-weight 與--cpu-shares 類似，設(shè)置的是相對(duì)權(quán)重值，默認(rèn)為500。在下面的例子中，容器A 讀寫磁盤的帶寬是容器B 的兩倍。

[root@localhost ~]# docker run -it --name container_A --blkio-weight 600 centos:stress /bin/bash

[root@ee06408457d8 /]# cat /sys/fs/cgroup/blkio/blkio.weight

600

[root@localhost ~]# docker run -it --name container_B --blkio-weight 300 centos:stress /bin/bash

[root@0ad7376f831b /]# cat /sys/fs/cgroup/blkio/blkio.weight

300

限制bps 和iops

如果在一臺(tái)服務(wù)器上進(jìn)行容器的混合部署，那么會(huì)存在同時(shí)幾個(gè)程序?qū)懘疟P數(shù)據(jù)的情況，這時(shí)可以通過--device-write-iops選項(xiàng)來限制每秒寫io次數(shù)來限制制定設(shè)備的寫速度。相應(yīng)的還有--device-read-iops選項(xiàng)可以限制讀取IO的速度，但是這種方法只能限制設(shè)備，而不能限制分區(qū)，相應(yīng)的Cgroup寫配置文件為/sys/fs/cgroup/blkio/容器ID/?blkio.throttle.write_iops_device。

1. bps 是byte per second，每秒讀寫的數(shù)據(jù)量。
2. iops 是io per second，每秒IO 的次數(shù)。

[root@localhost ~]# docker run -it --device-write-bps /dev/sda:5MB centos:stress /bin/bash

[root@bef94b99dc95 /]# dd if=/dev/zero of=test bs=1M count=100 oflag=direct

100+0 records in

100+0 records out

104857600 bytes (105 MB) copied, 20.0237 s, 5.2 MB/s