I'm continually getting vague reports of "slowness" with virtual desktops, however this one actually came with a verifiable, reproducible symptom.
When a user is typing in a browser or a document, at times, the display of characters lags behind the typing. Sometimes pretty far behind.
Right now I've got about 300 powered-on VMs on a Cisco UCS stack (8 B200M3s), using SSD for the replica disk and a 10G datacenter backbone, 1G to the clients. We have plenty of host resources and we should not have any I/O or network bottlenecks.
In the past, I've been directed to essentially throw resources at our virtual desktops, i.e. 1 vCPU, make it 2, now make it 4, etc., .etc.
My working hypothesis is that at 4 vCPU per desktop, I'm running into CPU scheduling issues. The problem reported coincides with a recent creation of a few additional pools of desktops, which essentially doubled the number of running VMs.
What should I look for to continue troubleshooting? I'd like to be able to show that by reducing the vCPU to a dual-core, this could free up the scheduling issue, assuming that is the problem.
If there's some other possible source of this problem, that'd be helpful to know too.