Difference between revisions of "util-vserver:Cgroups"
From Linux-VServer
Daniel hozac (Talk | contribs) m (Reverted edits by 127.0.0.1 (Talk); changed back to last version by 217.128.26.129) |
(→Draft - Cgroups and vservers) |
||
| Line 1: | Line 1: | ||
| − | + | Bears run away when you yell at them, even lynxes. , | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
== Draft - Distributing cpu shares with cgroups == | == Draft - Distributing cpu shares with cgroups == | ||
Revision as of 15:00, 23 October 2009
Bears run away when you yell at them, even lynxes. ,
Contents |
From what i gathered in sched-design-CFS.txt [1]
This is simply done by adjusting the cpu.shares. Just do:
echo '512' > /dev/cgroup/<guest name>/cpu.shares
The share you get is equal to the guest's share divided by the sum of the cpu shares of all the guest. So for exemple :
vserver guest 1 => 512 vserver guest 2 => 512 vserver guest 3 => 2048 vserver guest 4 => 512
so you have a total of 3584 cpu shares (2048+512+512+512) , then you get :
vserver guest 1 => 512 / 3584 = 14% cpu vserver guest 2 => 512 / 3584 = 14% cpu vserver guest 3 => 2048 / 3584 = 57% cpu vserver guest 4 => 512 / 3584 = 14% cpu
Note that this is fair scheduling and this will not enfore HARD limit (as far as i know).
You must use the "cgroup" directory. You can apply defaults to all vservers or choose different settings for each guest:
- /etc/vservers/.default/cgroup , this directory contains settings applying to all guest when they start
- /etc/vservers/<guestname>/cgroup , this directory contains settings for the guest when it starts.
Exemple :
mkdir /etc/vservers/.defaults/cgroup mkdir /etc/vservers/<guestname>/cgroup echo '2048' > /etc/vservers/<guestname>/cgroup/cpu.shares # List of CPUs echo 1 > /etc/vservers/<guestname>/cgroup/cpuset.cpus # NUMA nodes echo 1 > /etc/vservers/<guestname>/cgroup/cpuset.mems
Note that /etc/vservers is an exemple, in my Aqueos install i use /usr/local/etc/vservers but /etc/vservers seems to be the defaults for the classic installs.
Regards, Ghislain.
cgroup and CFS based CPU hard limiting that replaces sched_hard
This feature is currently available in patch-2.6.31.2-vs2.3.0.36.15.diff and is in testing phase as of this patch set so report any bugs to the mailing list.
Example for an upper bound of 2/5th (or 40%) of the all cpu power that a guest/cgroup can use :
# force CFS hard limit echo 1 > /etc/vservers/<guestname>/cgroup/cpu.cfs_hard_limit # time assigned to guest (in microseconds) 200000 = 0,2 sec echo 200000 > /etc/vservers/<guestname>/cgroup/cpu.cfs_runtime_us # in each specified period (in microseconds) 500000 = 0,5 sec echo 500000 > /etc/vservers/<guestname>/cgroup/cpu.cfs_period_us
This limit is an hard limit, see it like an upper wall for the ressources used by the cgroup. If you set both cpu share AND hard limit the system will do fine but hard limits takes priority over cpu share scheduling, so cpu share will do the job but each cgroup will have an upper bound that it cannot cross even if the cpu share you gived it is higher.
Hard limit feature adds 3 cgroup files for CFS group scheduler: cfs_runtime_us: Hard limit for the group in microseconds. cfs_period_us: Time period in microseconds within which hard limits is enforced. cfs_hard_limit: The control file to enable or disable hard limiting for the group.
real world exemples of scheduling
this part is to be filled with exemple you have put in place and are working and have been tested, please add the patch and kernel version for each exemple you put here.
