To support decisions regarding a host's capacity to run virtual machines, it is
useful to have an expanded set of guest memory statistics.  These should be
collected by the ovirt-guest-agent and made available by the vdsm getVmStats()
API.  Once this has been done, it will be possible to write a host-side MOM
policy for auto-ballooning.

The current set of vetted memory stats is published in the virtio specification: (Appendix G, page 42)

swap_in - the total number of pages swapped in
swap_out - the total number of pages swapped out
minflt - the total number of minor page faults 
majflt - the total number of major page faults
memfree - the amount of memory that is completely unused (in Linux: MemFree)
memtot - the total amount of available memory (in Linux: MemTotal)

In Linux, these values can all be obtained by reading /proc/meminfo and
/proc/vmstat.  On Windows there is an existing implementation in the virtio
balloon driver.

How does everyone feel about adding these to the current set of guest stats?

Adam Litke <>
IBM Linux Technology Center

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