OLD Intel® "Haswell" Generation Cluster: Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz 6 Core
NEW Intel® „Skylake“-Generation Cluster: Intel(R) Xeon(R) CPU Platinum 8168 @ 2.7GHz 24 Core
how much performance would i "loose" if i have a new cluster and choose to set EVC mode to Haswell even if its New Xeon Platinum CPUs. It would be a nice benefit to vmotion maschines between clusters but i dont wanna slow down the new hardware too much.
its around 200 VMs, mixed usage 50% Windows 50 % Linux, Exchange, MS servers. No big data rendering or high CPU usage stuff.
Well, Skylake is 2 years newer than Haswell but there is no really a way to measure the impact of enabling EVC... I mean, the impact in a different archicteture usually is with new features and new speed (as everytime is smaller) but it's quite hard to measure that.
Here is a White Paper that talks about: https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/vmware-vsphere-evc-perf...
if you read VMware Knowledge Base about EVC, you can see you are losing following instructions:
Transactional Synchronization Extensions, Supervisor Mode Access Prevention, Multi-Precision Add-Carry Instruction Extensions, PREFETCHW,RDSEED,
Advanced Vector Extensions 512 (AVX512), Persistent Memory Support Instructions, Protection Key Rights, Save Processor Extended States with Compaction, and Save Processor Extended States Supervisor.
Therefore if you're apps are not using any of those, I guess there will be no performance impact at all, especially if you are saying you have no high CPU usage stuff.
If you are decommissioning the old cluster, you can update EVC on the new one later. VMs will then get a new setting during next maintenance (you have to poweroff/on). Nobody will even notice the change.
For example I have 4 generations of CPUs in my environment, starting with IvyBridge and benefit of vmotion is bigger than performance boost between them. Most performance boost which you'll get since sandy bridge is from the increased number of cores per CPU. Although I have some clusters which have higher EVC, most of them are still at IvyBridge