root xyz ~ # oc version
This behavior (pods using swap space when they used up all the RAM
assigned to them) was confirmed on two independent clusters. I'll
test that with the OpenShift 1.0.7 as soon as we upgrade, but that
might take some time. Should I create a bug report right now or hold
off until we upgrade to 1.0.7?
Am 2015-11-03 um 02:09 schrieb Derek
I did not see in the original question the version of
OpenShift that was being exercised, but as of Jun 8, upstream
Kubernetes tells docker to disable memory swap for a container
when it launches. So if a limit is specified, the container
should not be able to access swap anymore in recent versions.
If a container is still able to access swap, it would be a
bug either in upstream Kubernetes or Docker that we would need
to track down.
As for allowing swap for other system processes, that won't
work when the Kubelet becomes more intelligent in handling
available memory on a node versus just its capacity
minus scheduled-pods. The long term plan is to allow a Kubelet
to dynamically adjust its reported available memory to the
scheduler to handle when system processes consume more memory as
load increases. For example, as more containers are run, docker
daemon itself consumes more memory.
On Monday, November 2, 2015, Andy Grimm <agrimm redhat com
Why wouldn't you at least set the memsw limit to
match the memory limit as a safeguard, though? There
doesn't seem to be any harm it that, even if best practice
is to disable it. Also, you could allow swappiness to be
set to zero for the pods to prevent them from swapping but
still allow other system processes to do so.
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