Comment 2 for bug 1830260

To try and get some idea of the performance regression around this I created an 8VCPU/8GB RAM devstack with 4 fake compute nodes and set API_WORKERS=1, and disabled some services I don't need like horizon/tempest/cinder to cut out their load on the host. I then created 150 servers across the 4 hosts:

stack@devstack:~$ openstack server list --host devstack1 | grep test-vm | wc -l
105
stack@devstack:~$ openstack server list --host devstack2 | grep test-vm | wc -l
10
stack@devstack:~$ openstack server list --host devstack3 | grep test-vm | wc -l
15
stack@devstack:~$ openstack server list --host devstack4 | grep test-vm | wc -l
20

Listing servers with the 2.16 microversion to get the host_status field takes somewhere between 1 and 2 seconds:

http://paste.openstack.org/show/753145/

I'll then try to fix this bug and compare the timings with the fix.