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最後更新: 2016-08-03
目睹
- cgroup 的 mount point
- systemd unit types
- Resource
- service unit file (Persistent Cgroups)
- Check status
- systemd-run
- 建立 Unit 及 CPUShares Test
- Cheat List
- user sessions
cgroup 的 mount point
# 找出 cgroup 的 mount point
grep ^cgroup /proc/mounts
cgroup /sys/fs/cgroup/systemd cgroup
rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd 0 0
cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
cgroup /sys/fs/cgroup/hugetlb cgroup rw,nosuid,nodev,noexec,relatime,hugetlb 0 0
cgroup /sys/fs/cgroup/net_cls cgroup rw,nosuid,nodev,noexec,relatime,net_cls 0 0
cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct,cpu 0 0
cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0* mounted automatically by systemd
# 列出 cgroup 的結構
systemd-cgls
├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 21
├─user.slice
│ └─user-0.slice
│ ├─session-634.scope
│ │ ├─31772 sshd: root@pts/0
│ │ ├─31777 -bash
│ │ ├─31961 systemd-cgls
│ │ └─31962 systemd-cgls
│ └─session-629.scope
│ ├─31530 /usr/sbin/CROND -n
│ ├─31536 /bin/bash /usr/share/clamav/freshclam-sleep
│ └─31551 sleep 765
└─system.slice
├─crond.service
│ └─1064 /usr/sbin/crond -n
├─httpd.service
│ ├─ 1059 /usr/sbin/httpd -DFOREGROUND
│ ├─ 2499 vlogger (access log
│ ├─ 2500 /usr/sbin/httpd -DFOREGROUND
│ ├─ 5718 /usr/bin/php-cgi -d magic_quotes_gpc=off -d session.save_path=/usr/local/ispconfig/interface/temp
│ ├─ 5720 /usr/bin/php-cgi -d magic_quotes_gpc=off -d session.save_path=/usr/local/ispconfig/interface/temp
│ ├─ 6295 /usr/bin/php-cgi -d magic_quotes_gpc=off -d session.save_path=/usr/local/ispconfig/interface/temp
│ ├─ 6299 /usr/bin/php-cgi -d magic_quotes_gpc=off -d session.save_path=/usr/local/ispconfig/interface/temp
│ ├─27942 /usr/sbin/httpd -DFOREGROUND
│ ├─30116 /usr/sbin/httpd -DFOREGROUND
│ ├─30502 /usr/sbin/httpd -DFOREGROUND
│ ├─31192 /usr/sbin/httpd -DFOREGROUND
.......................
systemd unit types
Types:
- Service
- Scope
- Slice
Service [name.service]
# 用 unit configureation file 啟動的 proccess
i.e.
/usr/lib/systemd/system/httpd.service
Scope [name.scope]
# A group of externally created processes ( fork() function )
* all user sessions are automatically placed in a separated scope unit,
as well as virtual machines and container processes.
Slice [parent-name.slice]
# Slices do not contain processes, they organize a hierarchy in which scopes and services are placed.
(The actual processes are contained in scopes or in services)
Default 有的 slice
1. root slice called "-.slice"
2. system.slice (the default place for all system services)
3. user.slice (the default place for all user sessions)
4. machine.slice (the default place for all virtual machines and Linux containers)
Resource
CPUShares
By default at 1024
MemoryLimit
By default without limit (Unit: K, M, G)
BlockIOWeight
By default 1000 (Value: 10 ~ 1000)
StartupCPUShares and StartupBlockIOWeight:
Its work like CPUShares and BlockIOWeight but only apply during system startup.
CPUQuota:
It restricts CPU time to the specified percentage, even if the machine is otherwise idle.
Service unit file (Persistent Cgroups)
# Default 的 Unit file 設定
在目錄 /usr/lib/systemd/system/ 內有不同 Service 的 Unit File
/usr/lib/systemd/system/httpd.service
..............
# To assign the Apache service 800 CPU shares
[Service]
CPUShares=800
MemoryLimit=500M
# a path to a block device node
# allows to limit a specific bandwidth for a unit
# the blkio resource controller does not support buffered write operations.
# Implies "BlockIOAccounting=yes"
# 它要指定 partition
BlockIOReadBandwith=/ 5M
BlockIOWriteBandwidth=/ 5M
# Changing Low-level Cgroup Attributes
ControlGroupAttribute=memory.swappiness 70# reload systemd's configuration
systemctl daemon-reload
# restart Apache so that the modified
systemctl restart httpd.service
Remark 沒有 "systemctl daemon-reload" 時會見到
Warning: httpd.service changed on disk. Run 'systemctl daemon-reload' to reload units.
# 由 command 設定
# 它是直接有效, 不用 "systemctl daemon-reload" 及 "systemctl restart httpd", Reboot 後依然有效 !!
systemctl set-property httpd.service MemoryLimit=300M
systemctl set-property httpd.service CPUShares=800
systemctl set-property httpd.service BlockIOReadBandwith='/ 5M'
# Limit Swap
systemctl set-property httpd.service ControlGroupAttribute="memory.swappiness 30"
systemctl set-property httpd.service ControlGroupAttribute="memory.memsw.limit_in_bytes 524288000"
此 command 會建立
/etc/systemd/system/httpd.service.d/50-MemoryLimit.conf
[Service] MemoryLimit=314572800
Check status
# list all active units on the system
systemctl [list-units]
Column
LOAD — indicates if the unit configuration file was properly loaded.
ACTIVE — the high-level unit activation state, which is a generalization of SUB.
SUB — the low-level unit activation state.
... loaded active running ...
# display detailed information about a system unit
systemctl status httpd
Drop-In: /etc/systemd/system/httpd.service.d
└─50-CPUShares.conf, 50-MemoryLimit.conf# a cgroup tree of the memory resource controller
systemd-cgls memory
memory: ├─ 1 /usr/lib/systemd/systemd --switched-root --system --deserialize 21 ├─1382 /sbin/agetty --noclear tty1 linux ├─user.slice │ ├─24215 sshd: root@pts/0 │ ├─24221 -bash │ ├─25579 systemd-cgls memory │ └─25580 systemd-cgls memory └─system.slice ├─pure-ftpd.service │ └─739 pure-ftpd (SERVER) ...
# Tasks %CPU Memory Input/s Output/s
systemd-cgtop
# To get the current CPUShares service
systemctl show -p CPUShares httpd.service
CPUShares=???
# -p, --property= comma-separated list
# systemctl show will show all available properties.
systemctl show -p MemoryLimit # Unit: bytes
MemoryLimit=???
systemd-run
Start a transient service or scope unit and run a custom command in this unit.
Usage
systemd-run --unit=unit_name --scope --slice=slice_name command
Optional
--unit # not specified => a unit name will be generated automatically
--scope # Default: service (running in the background)
--slice # Default: system.slice
e.g.
systemd-run --unit=dd-test dd if=/dev/mapper/centos-root of=/dev/null
systemctl status dd-test
● dd-test.service - /usr/bin/dd if=/dev/mapper/centos-root of=/dev/null
Loaded: loaded (/run/systemd/system/dd-test.service; static; vendor preset: disabled)
Drop-In: /run/systemd/system/dd-test.service.d
└─50-Description.conf, 50-ExecStart.conf
Active: active (running) since Thu 2016-08-04 10:01:59 HKT; 1min 2s ago
Main PID: 3403 (dd)
Memory: 323.5M
CGroup: /system.slice/dd-test.service
└─3403 /usr/bin/dd if=/dev/mapper/centos-root of=/dev/null
"static" => does not have permanent unit configuration
設定 runtime value
Transient cgroups are released automatically as soon as the processes they contain finish.
systemctl set-property --runtime unit_name property=value
e.g.
# 1Mbyte/s
systemctl set-property --runtime dd-test BlockIOReadBandwidth='/dev/mapper/centos-root 1M'
查看 dd status
kill -USR1 $(pgrep ^dd)
To terminate unit
systemctl kill dd-test.service
systemctl status dd-test
● dd-test.service
Loaded: not-found (Reason: No such file or directory)
Active: inactive (dead)
Test: 建立 Unit 去測試 CPUShares
/etc/systemd/system/sha1sum.service
[Unit]
Description=The sha1sum service that does nothing useful
After=remote-fs.target nss-lookup.target
[Service]
ExecStart=/usr/bin/sha1sum /dev/zero
ExecStop=/bin/kill -WINCH ${MAINPID}
[Install]
WantedBy=multi-user.target/etc/systemd/system/md5sum.service
[Unit]
Description=The md5sum service that does nothing useful
After=remote-fs.target nss-lookup.target
[Service]
ExecStart=/usr/bin/md5sum /dev/zero
ExecStop=/bin/kill -WINCH ${MAINPID}
[Install]
WantedBy=multi-user.targetsystemctl start md5sum
systemctl start sha1sum
systemctl set-property md5sum CPUShares=700
systemctl set-property sha1sum CPUShares=300
# 找出它們的 pid
systemctl show md5sum | grep MainPID
systemctl show md5sum | grep MainPID
# 查看 CPU 情況
ps -p 2662,2668 -o pid,comm,cputime,%cpu
PID COMMAND TIME %CPU 2662 md5sum 02:01:35 69.7 2668 sha1sum 00:52:32 30.1
Cheat List
set-property
systemctl set-property httpd.service MemoryLimit=300M
systemctl set-property httpd.service CPUShares=800
systemctl set-property httpd.service BlockIOReadBandwith='/ 5M'
systemctl set-property httpd.service ControlGroupAttribute="memory.swappiness 30"
systemctl set-property httpd.service ControlGroupAttribute="memory.memsw.limit_in_bytes 524288000"
user sessions
user-1000.slice
Other
machinectl
used to introspect and control the state of the systemd(1) virtual machine and
container registration manager systemd-machined.service
Doc
https://www.freedesktop.org/software/systemd/man/systemd.directives.html
man systemd.exec
man systemd.resource-control
man systemd-system.conf
