Hi, I'm new to Watcher and would like to do some performance and scale testing in a simulated environment and wondering if anyone can give some pointers on what I could be testing or looking for. If possible, I'd like to be able to just setup a single-node devstack with the nova fake virt driver which allows me to create dozens of fake compute nodes. I could also create multiple cells with devstack, but there gets to be a limit with how much you can cram into a single node 8GB RAM 8VCPU VM (I could maybe split 20 nodes across 2 cells). I could then create dozens of VMs to fill into those compute nodes. I'm mostly trying to figure out what could be an interesting set of tests. The biggest problem I'm trying to solve with Watcher is optimizing resource utilization, i.e. once the computes hit the Tetris problem and there is some room on some nodes but none of the nodes are fully packed. I was thinking I could simulate this by configuring nova so it spreads rather than packs VMs onto hosts (or just use the chance scheduler which randomly picks a host), using VMs of varying sizes, and then run some audit / action plan (I'm still learning the terminology here) to live migrate the VMs such that they get packed onto as few hosts as possible and see how long that takes. Naturally with devstack using fake nodes and no networking on the VMs, that live migration is basically a noop, but I'm more interested in profiling how long it takes Watcher itself to execute the actions. Once I get to know a bit more about how Watcher works, I could help with optimizing some of the nova-specific stuff using placement [1]. Any advice or guidance here would be appreciated. [1] https://review.opendev.org/#/c/656448/ -- Thanks, Matt