RHEA-2014:0064 - Product Enhancement Advisory

Topic

A new Memory Overcommitment Manager package is now available.

Description

Memory Overcommitment Manager (MOM) is a policy-driven tool for managing
overcommitment on KVM hosts. Using libvirt, MOM monitors active virtual machines
on hosts, and dynamically configures memory overcommitment policies. MOM
supports control of memory ballooning and Kernel Samepage Merging (KSM).

This update fixes the following bugs:

• Previously the HostKSM collector calculated the number of jiffies that have

been used since the last collection period. However, the count accumulated
indefinitely as it was never reset, which could lead to failure of
ovirt-engine-dwhd. This issue is fixed by calculating the current number of
jiffies used, so get_ksmd_cpu_usage returns the correct results. (BZ#999973)

• When the hypervisor's memory pressure grows, MOM is supposed to reduce guests'

memory to make more memory available to the hypervisor. But instead of selecting
only the guests with free memory available, MOM reduced all guests' memory, so
guests with high memory load had to use swap. This issue is fixed with enhanced
ballooning rules for computing the minimum available memory and reporting the
swap usage of the guests. (BZ#1025845)

All users who require MOM on virtualization hosts are advised to install these
new packages.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/site/articles/11258

Affected Products

• Red Hat Virtualization 3 for RHEL 6 x86_64

Fixes

• BZ - 967562 - PRD33 - mom integration - ksm regression testing
• BZ - 999973 - get_ksmd_cpu_usage returns incorrect results
• BZ - 1025845 - MOM is ballooning all VMs at once, even VMs without free memory enough.

CVEs

(none)

References

(none)