System information

Kernel Control Groups 125
# Create a child cgroup:
mkdir /freezer/0
# Put a task into this cgroup:
echo $task_pid > /freezer/0/tasks
# Freeze it:
echo FROZEN > /freezer/0/freezer.state
# Unfreeze (thaw) it:
echo THAWED > /freezer/0/freezer.state
Checkpoint/Restart (Control)
Save the state of all processes in a cgroup to a dump file. Restart it later (or just
save the state and continue).
Move a “saved container” between physical machines (as VM can do).
Dump all process images of a cgroup to a file.
Devices (Isolation)
A system administrator can provide a list of devices that can be accessed by
processes under cgroups.
It limits access to a device or a file system on a device to only tasks that belong
to the specified cgroup. For more information, see /usr/src/linux/Docu
mentation/cgroups/devices.txt.
Cpuacct (Control)
The CPU accounting controller groups tasks using cgroups and accounts the CPU
usage of these groups. For more information, see /usr/src/linux/Docu
mentation/cgroups/cpuacct.txt.
CPU (Resource Control)
Share CPU bandwidth between groups with the group scheduling function of CFS
(the scheduler). Mechanically complicated.
Memory (Resource Control)
• Limits memory usage of user space processes.
• Control swap usage by setting swapaccount=1 as a kernel boot para-
meter.
• Limit LRU (Least Recently Used) pages.