1. Feature
Memory guarantees for Containers and Virtual Machines
https://jira.sw.ru/browse/PSBM-42670
2. Description
It's possible to define memory guarantees for both Containers and Virtual
Machines.
VCMMD must ensure dynamic memory configuration of Virtual Environments never
screw up defined VEs memory guarantees.
How to set up memory guarantee for a VE:
# prlctl set VE --memguarantee [%]
Examples:
prlctl set VE --memguarantee 50
prlctl set VE --memguarantee auto
Note: "auto" is for default value (40% for VMs, 20% for CTs)
Unlimited Containers have [FIXME] % memory guarantees by default.
(Virtual Machines cannot be "unlimited" by design.)
3. Products
Virtuozzo 7
Packages:
vcmmd-7.0.38-1
vzkernel-3.10.0-229.7.2.vz7.9.29
prl-disp-service-7.0.235
prlctl-7.0.33
vzctl-7.0.85
4. Testing
* host RAM=X, total sum of currently running VEs = Y (Y<X)
You are trying to start a VE with memory guarantee Z (or increase the memory
guarantee for existing VE to Z).
a) if Z > X - Y - min(X*0.05, 1Gb), operation should fail
b) if Z < (X - Y - min(X*0.05, 1Gb)) * 0.95, operation should succeed
* for each running VE, it should be able to allocate and use memory without OOM,
if total VE usage is not greater than VE's memory limit
* Attempt to set --memquota must fail (otherwise - broken expectations) and
print reasonable error message,
like "This option is deprecated, please use —memguarantee instead".
https://jira.sw.ru/browse/PSBM-41963
5. Known issues
* 'prlctl start VM' is the only way to start VM with memory guarantee
(In other words in case you start a VM via virsh, memory guarantees won't
work for sure.)
https://jira.sw.ru/browse/PSBM-43106
6. What was checked by developer
* cgroups' lowlimit never goes lower than memory guarantees set for a Container
7. Feature owner
vcmmd part - vdavy...@virtuozzo.com
prlctl part - dandr...@virtuozzo.com
dispatcher parts - shr...@virtuozzo.com, i...@virtuozzo.com,
dandr...@virtuozzo.com
vzctl part - i...@virtuozzo.com
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