vm-balancer

kvm virtual machine load balancer and scheduler

vm-balancer is a virtual machine load balancer for KVM hypervisor(w/QEMU & libvirt) -It is capable of efficiently balancing virtual machine loads among up to 8 logical cores(so 4 physical for now) -very helpful for managing images that are quickly spun up and destroyed with no persistence; e.g. cloud images. Potentially offers speedup and host memory savings when run against native qemu auto-ballooning and repin drivers.

VM CPU BALANCER: -the balancer will dynamically repin vcpus for all active vm domains to physical cpus to ensure load balance.

compile & run:

1. make && sudo ./vcpu_scheduler quantum is the period in seconds to run the vcpu_scheduler and must be greater than zero

operation:

operation:

1. cpu balancer connects to hypervisor session through default uri
2. starts sleep by quantum loop, initial setup, pinning, turn off auto-balloon, etc(initial pinning is done to disable internal qemu auto repinning)
3. gather stats and calculate weighted usage for all vcpus and cpus
4. Find busiest and freest cpus. If freest cpu has no vcpus pinned to it, pin first vcpu in queue currently pinned to busiest cpu and continue loop
5. else if busiest cpu usage > 50% threshold and freest cpu < 50% threshold AND busiest cpu has > 1 vcpu pinned to it, pin freest vcpu from busiest cpu to freest cpu if still below threshold. So, every period, make sure the busiest and freest cpus come closer in terms of usage.(e.g. minimize the difference in usage between freest and busiest cpus)
6. repeat

VM MEM BALANCER: -attempts to efficiently reclaim memory from guest vms and distribute memory from a host hypervisor pool to starved guest vms.

compile & run:

1. make && sudo ./memory_coordinator quantum is the period in seconds to run the memory coordinator and must be greater than zero

operation:

1. mem balancer connects to hypervisor session through default uri
2. starts sleep by quantum loop, initial setup, pinning, turn off auto-balloon, etc
3. gather stats and calculate weighted usage
4. for all vms, if a vm's mem usage is above the free threshold(256mb), reclaim the difference / factor where factor is currently 2.
5. if a vms usage is starved(below starve threshold 128mb) and it has not given memory to hypervisor pool, give THRESH_STARVE, where THRESH_STARVE is 128mb * time quantum. if the host does not have enough memory to give, stop. Essentially, set the domain memory to: used memory + thresh starve bytes(128mb) * quantum. This works out to generally giving starved vms a share of the reclaimed memory each period.
6. necessary checks for out-of-memory for host
7. repeat