linux的cgroup理论：https://www.cnblogs.com/menkeyi/p/10941843.html
容器的资源隔离就是基于linux的cgroup实现。
1.实践linux cgroup
[crmop@localhost ~]$ mount -t cgroup ##查看cgroup挂载，子目录（cpuset即cpu核数,cpu,memory）表示可以被cgroup限制的资源种类
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids)
cgroup on /sys/fs/cgroup/rdma type cgroup (rw,nosuid,nodev,noexec,relatime,rdma)
[root@localhost ~]# cd /sys/fs/cgroup [root@localhost cgroup]# ls ##子目录（cpuset即cpu核数,cpu,memory）表示可以被cgroup限制的资源种类 blkio cpuacct cpuset freezer memory net_cls,net_prio perf_event rdma cpu cpu,cpuacct devices hugetlb net_cls net_prio pids systemd [root@localhost cgroup]# cd cpu ##对cpu子系统来说，提供具体可以被限制的方法，如cfs_period_us与cfs_quota_us组合，
##表示在cfs_period_us时间长度内分得cfs_quota_us的cpu时间，即限制cpu的最高使用率为cfs_quota_us/cfs_period_us*100% [root@localhost cpu]# ls cgroup.clone_children cpuacct.usage cpuacct.usage_percpu_user cpu.cfs_quota_us cpu.stat cgroup.procs cpuacct.usage_all cpuacct.usage_sys cpu.rt_period_us notify_on_release cgroup.sane_behavior cpuacct.usage_percpu cpuacct.usage_user cpu.rt_runtime_us release_agent cpuacct.stat cpuacct.usage_percpu_sys cpu.cfs_period_us cpu.shares tasks [root@localhost cpu]# ll total 0 -rw-r--r-- 1 root root 0 Aug 15 00:55 cgroup.clone_children -rw-r--r-- 1 root root 0 Jun 4 10:18 cgroup.procs -r--r--r-- 1 root root 0 Aug 15 00:55 cgroup.sane_behavior -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.stat -rw-r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_all -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_percpu -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_percpu_sys -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_percpu_user -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_sys -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_user -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.cfs_period_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.cfs_quota_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.rt_period_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.rt_runtime_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.shares -r--r--r-- 1 root root 0 Aug 15 00:55 cpu.stat -rw-r--r-- 1 root root 0 Aug 15 00:55 notify_on_release -rw-r--r-- 1 root root 0 Aug 15 00:55 release_agent -rw-r--r-- 1 root root 0 Aug 15 00:55 tasks [root@localhost cpu]# mkdir container ##这个目录称为一个“控制组”，在该目录下，自动生成该子系统对应的资源限制文件 [root@localhost cpu]# ll total 0 -rw-r--r-- 1 root root 0 Aug 15 00:55 cgroup.clone_children -rw-r--r-- 1 root root 0 Jun 4 10:18 cgroup.procs -r--r--r-- 1 root root 0 Aug 15 00:55 cgroup.sane_behavior drwxr-xr-x 2 root root 0 Aug 15 00:56 container -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.stat -rw-r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_all -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_percpu -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_percpu_sys -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_percpu_user -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_sys -r--r--r-- 1 root root 0 Aug 15 00:55 cpuacct.usage_user -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.cfs_period_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.cfs_quota_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.rt_period_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.rt_runtime_us -rw-r--r-- 1 root root 0 Aug 15 00:55 cpu.shares -r--r--r-- 1 root root 0 Aug 15 00:55 cpu.stat -rw-r--r-- 1 root root 0 Aug 15 00:55 notify_on_release -rw-r--r-- 1 root root 0 Aug 15 00:55 release_agent -rw-r--r-- 1 root root 0 Aug 15 00:55 tasks [root@localhost cpu]# cd container/ [root@localhost container]# ls cgroup.clone_children cpuacct.usage cpuacct.usage_percpu_sys cpuacct.usage_user cpu.rt_period_us cpu.stat cgroup.procs cpuacct.usage_all cpuacct.usage_percpu_user cpu.cfs_period_us cpu.rt_runtime_us notify_on_release cpuacct.stat cpuacct.usage_percpu cpuacct.usage_sys cpu.cfs_quota_us cpu.shares tasks [root@localhost container]# ls cgroup.clone_children cpuacct.usage cpuacct.usage_percpu_sys cpuacct.usage_user cpu.rt_period_us cpu.stat cgroup.procs cpuacct.usage_all cpuacct.usage_percpu_user cpu.cfs_period_us cpu.rt_runtime_us notify_on_release cpuacct.stat cpuacct.usage_percpu cpuacct.usage_sys cpu.cfs_quota_us cpu.shares tasks [root@localhost container]# cat cpu.cfs_period_us 100000 [root@localhost container]# cat cpu.cfs_quota_us ## -1表示不作限制 -1 [root@localhost container]# cat tasks [root@localhost container]# top top - 00:58:19 up 2 days, 7:05, 2 users, load average: 0.01, 0.03, 0.00 Tasks: 187 total, 1 running, 133 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.0 us, 0.3 sy, 0.0 ni, 99.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 977804 total, 149268 free, 608916 used, 219620 buff/cache KiB Swap: 1048572 total, 1031848 free, 16724 used. 178692 avail Mem
写一个死循环且不作限制，cpu被打满
[root@localhost container]# while : ; do : ; done & [1] 35789 [root@localhost container]# top top - 00:59:04 up 2 days, 7:05, 2 users, load average: 0.16, 0.06, 0.01 Tasks: 187 total, 2 running, 132 sleeping, 0 stopped, 0 zombie %Cpu(s):100.0 us, 0.0 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 977804 total, 151268 free, 606924 used, 219612 buff/cache KiB Swap: 1048572 total, 1031848 free, 16724 used. 180692 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
35789 root 20 0 116376 1328 0 R 99.3 0.1 0:13.47 bash
作资源隔离限制
[root@localhost container]# pwd /sys/fs/cgroup/cpu/container [root@localhost container]# cat cpu.cfs_period_us 100000 [root@localhost container]# cat cpu.cfs_quota_us -1 [root@localhost container]# echo 20000 > cpu.cfs_quota_us ##及限制cpu最高作用率为20% [root@localhost container]# cat cpu.cfs_quota_us 20000 [root@localhost container]# cat tasks [root@localhost container]# echo 35798 > tasks ## 将该进程对应的pid写入对应控制组container的tasks文件 [root@localhost container]# cat tasks 35798 [root@localhost container]# top top - 01:04:12 up 2 days, 7:11, 2 users, load average: 0.80, 0.46, 0.19 Tasks: 189 total, 2 running, 132 sleeping, 0 stopped, 0 zombie %Cpu(s): 12.9 us, 0.4 sy, 0.0 ni, 86.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 977804 total, 149876 free, 608284 used, 219644 buff/cache KiB Swap: 1048572 total, 1031848 free, 16724 used. 179316 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 35798 root 20 0 116376 1328 0 R 19.9 0.1 2:16.42 bash 1157 gdm 20 0 2975120 186892 26480 S 1.0 19.1 3:46.17 gnome-shell
2.docker实践
启动一个容器 docker启动busybox
-i表示输入有效。
-t表示提供一个伪终端，用于我们输入内容。
[root@localhost container]# docker run -it --cpu-period=100000 --cpu-quota=20000 --name my-busybox1 docker.io/busybox /bin/sh
/ # top
Mem: 841296K used, 136508K free, 18500K shrd, 0K buff, 151804K cached
CPU: 0.0% usr 10.0% sys 0.0% nic 90.0% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.00 0.00 0.02 2/365 6
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1 0 root S 1308 0.1 0 0.0 /bin/sh
6 1 root R 1304 0.1 0 0.0 top
Mem: 842244K used, 135560K free, 18500K shrd, 0K buff, 151892K cached
CPU: 1.2% usr 0.6% sys 0.0% nic 97.5% idle 0.6% io 0.0% irq 0.0% sirq
Load average: 0.00 0.00 0.02 3/365 6
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1 0 root S 1308 0.1 0 0.0 /bin/sh
6 1 root R 1304 0.1 0 0.0 top
Mem: 842276K used, 135528K free, 18500K shrd, 0K buff, 151892K cached
CPU: 0.4% usr 0.4% sys 0.0% nic 99.1% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.00 0.00 0.02 2/365 6
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1 0 root S 1308 0.1 0 0.0 /bin/sh
6 1 root R 1304 0.1 0 0.0 top
/ # ps -ef
PID USER TIME COMMAND
1 root 0:00 /bin/sh
7 root 0:00 ps -ef
退出后重新启动已暂停的容器
docker ps查看正在运行的容器列表
[root@localhost container]# docker ps -a ##查看已经暂停的容器 CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9b8c4b4cce0d docker.io/busybox "/bin/sh" About an hour ago Exited (130) 6 minutes ago my-busybox1 [root@localhost container]# docker start 9b8c4b4cce0d ## 启动 9b8c4b4cce0d [root@localhost container]#
进入容器，加入一个死循环，容器内查看cpu使用率
[root@localhost cpu]# docker exec -it 9b8c4b4cce0d /bin/sh
/ # while : ; do : ; done &
/ # top
Mem: 869356K used, 108448K free, 18536K shrd, 0K buff, 167576K cached
CPU: 20.0% usr 0.0% sys 0.0% nic 80.0% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.03 0.02 0.00 3/374 12
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
11 6 root R 1308 0.1 0 20.0 /bin/sh
6 0 root S 1312 0.1 0 0.0 /bin/sh
1 0 root S 1308 0.1 0 0.0 /bin/sh
12 6 root R 1304 0.1 0 0.0 top
容器外查看，说明容器内的top命令查看的资源是宿主机上，验证了容器只是挂载文件目录，内核还是用的宿主机操作系统内核
同时37732进程即为容器实例的进程，说明容器本质就是一个特殊进程
[root@localhost ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9b8c4b4cce0d docker.io/busybox "/bin/sh" About an hour ago Up 8 minutes my-busybox1 [root@localhost ~]# top top - 02:56:52 up 2 days, 9:03, 2 users, load average: 0.04, 0.02, 0.00 Tasks: 197 total, 5 running, 141 sleeping, 0 stopped, 0 zombie %Cpu(s): 18.8 us, 0.3 sy, 0.0 ni, 80.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 977804 total, 84432 free, 683024 used, 210348 buff/cache KiB Swap: 1048572 total, 999976 free, 48596 used. 133088 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 37732 root 20 0 1308 60 4 R 19.9 0.0 0:36.01 sh 1164 mysql 20 0 1119840 156260 0 S 0.3 16.0 2:22.78 mysqld
在容器外的cgroup并未找到相关的控制组，但在容器内找到对应的限制pid 11
[root@localhost cpu]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
9b8c4b4cce0d docker.io/busybox "/bin/sh" About an hour ago Up 22 minutes my-busybox1
[root@localhost cpu]# top
top - 03:17:02 up 2 days, 9:23, 2 users, load average: 0.41, 0.32, 0.21
Tasks: 198 total, 2 running, 143 sleeping, 0 stopped, 0 zombie
%Cpu(s): 16.7 us, 5.6 sy, 0.0 ni, 72.2 id, 5.6 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 977804 total, 83188 free, 686168 used, 208448 buff/cache
KiB Swap: 1048572 total, 972028 free, 76544 used. 106920 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
37732 root 20 0 1308 56 0 R 12.5 0.0 4:37.74 sh
38908 root 20 0 162028 4580 3864 R 6.2 0.5 0:00.02 top
1 root 20 0 191316 3152 1524 S 0.0 0.3 0:09.62 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.05 kthreadd
3 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_gp
4 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_par_gp
6 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 kworker/0:0H-kb
8 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 mm_percpu_wq
9 root 20 0 0 0 0 S 0.0 0.0 0:08.29 ksoftirqd/0
10 root 20 0 0 0 0 I 0.0 0.0 0:06.56 rcu_sched
11 root rt 0 0 0 0 S 0.0 0.0 0:01.99 migration/0
13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 cpuhp/0
14 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kdevtmpfs
15 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 netns
16 root 20 0 0 0 0 S 0.0 0.0 0:00.03 kauditd
17 root 20 0 0 0 0 S 0.0 0.0 0:00.20 khungtaskd
18 root 20 0 0 0 0 S 0.0 0.0 0:00.00 oom_reaper
19 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 writeback
20 root 20 0 0 0 0 S 0.0 0.0 0:00.59 kcompactd0
21 root 25 5 0 0 0 S 0.0 0.0 0:00.00 ksmd
22 root 39 19 0 0 0 S 0.0 0.0 0:04.96 khugepaged
112 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 kintegrityd
[root@localhost cpu]# cd /sys/fs/cgroup/
[root@localhost cgroup]# ls
blkio cpuacct cpuset freezer memory net_cls,net_prio perf_event rdma
cpu cpu,cpuacct devices hugetlb net_cls net_prio pids systemd
[root@localhost cgroup]# cd cpu
[root@localhost cpu]# ls
cgroup.clone_children cpuacct.stat cpuacct.usage_percpu_sys cpu.cfs_period_us cpu.shares system.slice
cgroup.procs cpuacct.usage cpuacct.usage_percpu_user cpu.cfs_quota_us cpu.stat tasks
cgroup.sane_behavior cpuacct.usage_all cpuacct.usage_sys cpu.rt_period_us notify_on_release user.slice
container cpuacct.usage_percpu cpuacct.usage_user cpu.rt_runtime_us release_agent
[root@localhost cpu]# cd ..
[root@localhost cgroup]# grep 37732 */tasks
rdma/tasks:37732
[root@localhost cgroup]# cd cpu
[root@localhost cpu]# grep 37732 */tasks
[root@localhost cpu]#
[root@localhost ~]# docker exec -it 9b8c4b4cce0d /bin/sh
/ # cd /sys/fs/cgroup/
/sys/fs/cgroup # ls
blkio cpuacct freezer net_cls perf_event systemd
cpu cpuset hugetlb net_cls,net_prio pids
cpu,cpuacct devices memory net_prio rdma
/sys/fs/cgroup # cd cpu
/sys/fs/cgroup/cpu,cpuacct # ls
cgroup.clone_children cpu.rt_runtime_us cpuacct.usage_all cpuacct.usage_user
cgroup.procs cpu.shares cpuacct.usage_percpu notify_on_release
cpu.cfs_period_us cpu.stat cpuacct.usage_percpu_sys tasks
cpu.cfs_quota_us cpuacct.stat cpuacct.usage_percpu_user
cpu.rt_period_us cpuacct.usage cpuacct.usage_sys
/sys/fs/cgroup/cpu,cpuacct # cd ..
/sys/fs/cgroup # ls
blkio cpuacct freezer net_cls perf_event systemd
cpu cpuset hugetlb net_cls,net_prio pids
cpu,cpuacct devices memory net_prio rdma
/sys/fs/cgroup # cd cpu
/sys/fs/cgroup/cpu,cpuacct # ls
cgroup.clone_children cpu.rt_runtime_us cpuacct.usage_all cpuacct.usage_user
cgroup.procs cpu.shares cpuacct.usage_percpu notify_on_release
cpu.cfs_period_us cpu.stat cpuacct.usage_percpu_sys tasks
cpu.cfs_quota_us cpuacct.stat cpuacct.usage_percpu_user
cpu.rt_period_us cpuacct.usage cpuacct.usage_sys
/sys/fs/cgroup/cpu,cpuacct # ll
/bin/sh: ll: not found
/sys/fs/cgroup/cpu,cpuacct # ls
cgroup.clone_children cpu.rt_runtime_us cpuacct.usage_all cpuacct.usage_user
cgroup.procs cpu.shares cpuacct.usage_percpu notify_on_release
cpu.cfs_period_us cpu.stat cpuacct.usage_percpu_sys tasks
cpu.cfs_quota_us cpuacct.stat cpuacct.usage_percpu_user
cpu.rt_period_us cpuacct.usage cpuacct.usage_sys
/sys/fs/cgroup/cpu,cpuacct # ls -l
total 0
-rw-r--r-- 1 root root 0 Aug 15 10:10 cgroup.clone_children
-rw-r--r-- 1 root root 0 Aug 15 10:09 cgroup.procs
-rw-r--r-- 1 root root 0 Aug 15 09:47 cpu.cfs_period_us
-rw-r--r-- 1 root root 0 Aug 15 09:47 cpu.cfs_quota_us
-rw-r--r-- 1 root root 0 Aug 15 10:10 cpu.rt_period_us
-rw-r--r-- 1 root root 0 Aug 15 10:10 cpu.rt_runtime_us
-rw-r--r-- 1 root root 0 Aug 15 09:47 cpu.shares
-r--r--r-- 1 root root 0 Aug 15 10:10 cpu.stat
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.stat
-rw-r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage_all
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage_percpu
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage_percpu_sys
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage_percpu_user
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage_sys
-r--r--r-- 1 root root 0 Aug 15 10:10 cpuacct.usage_user
-rw-r--r-- 1 root root 0 Aug 15 10:10 notify_on_release
-rw-r--r-- 1 root root 0 Aug 15 10:10 tasks
/sys/fs/cgroup/cpu,cpuacct # cat tasks
1
11
13
24
/sys/fs/cgroup/cpu,cpuacct # top
Mem: 897488K used, 80316K free, 18616K shrd, 0K buff, 181188K cached
CPU: 27.2% usr 0.0% sys 0.0% nic 72.7% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.40 0.34 0.18 4/389 25
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
11 1 root R 1308 0.1 0 27.2 /bin/sh
13 0 root S 1316 0.1 0 0.0 /bin/sh
1 0 root S 1308 0.1 0 0.0 /bin/sh
25 13 root R 1304 0.1 0 0.0 top
/sys/fs/cgroup/cpu,cpuacct #
/sys/fs/cgroup/cpu,cpuacct #
/sys/fs/cgroup/cpu,cpuacct # ll
/bin/sh: ll: not found
/sys/fs/cgroup/cpu,cpuacct # ls
cgroup.clone_children cpu.rt_runtime_us cpuacct.usage_all cpuacct.usage_user
cgroup.procs cpu.shares cpuacct.usage_percpu notify_on_release
cpu.cfs_period_us cpu.stat cpuacct.usage_percpu_sys tasks
cpu.cfs_quota_us cpuacct.stat cpuacct.usage_percpu_user
cpu.rt_period_us cpuacct.usage cpuacct.usage_sys
/sys/fs/cgroup/cpu,cpuacct # cat cpu.cfs_quota_us
20000
/sys/fs/cgroup/cpu,cpuacct # cat cpu.cfs_period_us
100000
/sys/fs/cgroup/cpu,cpuacct # cat tasks
1
11
13
29
/sys/fs/cgroup/cpu,cpuacct #