Description of problem:
During normal usage, VDSM monitors the VM to gather statistics and report them to Engine. To do so, it must use the less amount of host resource as possible,
in order to leave them for VMs.
This is a generic tracker bug for improvements in this area.
after long discussion, many failed attempts and lot of tinkering, patches posted
the new libvirt bulk stats API are an improvement, even more in the long term.
But the biggest source of load is the disk usage threshold check.
This alone drives up the frequency of polling to very high rates.
Once we get events to be notified of disk usage threshold exceeded, we can greatly reduce the frequency of polling to sane values, thus greatly reducing the load of the system and improving the resource usage.
changing to RFE, the improvements is very significant in cases of high number of VMs per host.
Estimated improvements are in order of 2-4 times less CPU usage
VDSM patches all merged for 4.17.0 (oVirt 3.6.0)
MOM needs to be updated (work in progress on that front)
Moving to MODIFIED
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