5:53 a.m.
Hello,
iam currently trying to run LXC Containers with libvirt
but the memory limit doesn't want to work
in the container i see the full 32GB from the Host OS
iam pretty sure that iam missing a configline in the xml
lxc-template ~ # free -m
total used free shared buff/cache
available
Mem: 32108 626 31396 249 85
31396
Swap: 0 0 0
lxc-template ~ #
the host is running debian 9 with default repos
hv1 ~ # dpkg -l | grep virt
ii libgovirt-common 0.3.4-2
all GObject-based library to access oVirt REST API
(common files)
ii libgovirt2:amd64 0.3.4-2
amd64 GObject-based library to access oVirt REST API
ii libvirt-clients 3.0.0-4+deb9u3
amd64 Programs for the libvirt library
ii libvirt-daemon 3.0.0-4+deb9u3
amd64 Virtualization daemon
ii libvirt-daemon-system 3.0.0-4+deb9u3
amd64 Libvirt daemon configuration files
ii libvirt-glib-1.0-0:amd64 1.0.0-1
amd64 libvirt GLib and GObject mapping library
ii libvirt0 3.0.0-4+deb9u3
amd64 library for interfacing with different
virtualization systems
ii python-libvirt 3.0.0-2
amd64 libvirt Python bindings
ii qemu-kvm 1:2.8+dfsg-6+deb9u4
amd64 QEMU Full virtualization on x86 hardware
ii virt-viewer 5.0-1
amd64 Displaying the graphical console of a virtual
machine
ii virtinst 1:1.4.0-5
all Programs to create and clone virtual machines
--
best regards
Markus Raps
11:06 a.m.
Ok
somehow the processes bypasses the group/namespace
under libvirt the cgroups.procs file (
/sys/fs/cgroup/memory/machine/lxc-4296-deb4.libvirt-lxc/cgroup.procs )
shows only one process
with the lxc tools the cgroups.procs file (
/sys/fs/cgroup/memory/lxc/debian/cgroup.procs )
shows up to all 11 processes
--
Mit freundlichen Grüßen / best regards
Markus Raps
3:35 a.m.
On Wed, Aug 01, 2018 at 12:53:58PM +0200, Markus Raps wrote:
Hello,
iam currently trying to run LXC Containers with libvirt
but the memory limit doesn't want to work
in the container i see the full 32GB from the Host OS
iam pretty sure that iam missing a configline in the xml
lxc-template ~ # free -m
total used free shared buff/cache
available
Mem: 32108 626 31396 249 85
31396
Swap: 0 0 0
lxc-template ~ #
The 'free' command reports what is present in the host, which is distinct
from what's made available to the container. This isn't unique to libvirt
LXC containers - in fact any command that is runnning in a cgroup with
memory controller limits applied will see the same behaviour. Apps can't
assume that 'free' reflects the amount of memory that is available to
them. Instead they need to look at cgroups memory controller that they
are placed under (/proc/self/cgroups tells you where)
Regards,
Daniel
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9:53 a.m.
On 06.08.2018 10:35, Daniel P. Berrangé wrote:
The 'free' command reports what is present in the host, which
is distinct
from what's made available to the container. This isn't unique to libvirt
LXC containers - in fact any command that is runnning in a cgroup with
memory controller limits applied will see the same behaviour. Apps can't
assume that 'free' reflects the amount of memory that is available to
them. Instead they need to look at cgroups memory controller that they
are placed under (/proc/self/cgroups tells you where)
I think this is not
completely true... I had a similiar problem in the
past, and I could get it fixed by using e.g. this in the domains XML:
<memtune>
<hard_limit unit='KiB'>4194304</hard_limit>
<soft_limit unit='KiB'>4194304</soft_limit>
<swap_hard_limit unit='KiB'>4194304</swap_hard_limit>
</memtune>
`free` then reports the correct values. Maybe you can give that a try
@Markus Raps? Of course make sure to check out the documentation[1] of
these config elements to make sure you really want what they do.
Regards
Rene
[1] = https://libvirt.org/formatdomain.html#elementsMemoryTuning
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3 comments
3 participants
participants (3)
-
Daniel P. Berrangé -
Markus Raps -
Rene Pasing