1. 1. Best Practices for vCPU to CPU Ratio Management By: Matt Ray
2. 2. What Performance Goals Are You Optimizing? This is a great article about the allocation of vCPU to CPU core allocation for workload performance. But what is the real goal: performance of associated workloads? We may be taking the wrong approach. 2
3. 3. Sweat The Details A computation-intensive workload is capable of an overcommit ratio of up to 6:1, but averages 3:1. What does that mean??? Nothing without knowing the workload. 3
4. 4. Lets Walk Through An Example Lets figure out that problem. How many vCPUs are allocated to the VMs? If each VM has 8 vCPU, you need less than than 2 vCPUs per VM. What is the utilization characteristic? If you have 100% CPU use for 100% of the time by 100% of your VMs? Why would you provision over 1:1, let alone 6:1? 4
5. 5. Many Factors Go Into The Optimal vCPU:CPU Ratio When workloads change magic number changes! In reality: There exists no rule of thumb in business critical IT environments. Yet people will insist on it! 5
6. 6. 6 Changes in vCPU utilization this morning
7. 7. Lets Learn Something From Air Travel 7
8. 8. Flying Boston to Chicago 8 Your jet needs between and a full tank of fuel to make it. Normally, it only needs of a tank to make it. But are you comfortable with only filling up the tank of the way? Or would you play it conservative and waste fuel?
9. 9. Heres What Airlines Actually Do 9 They use advanced modeling to determine the right amount of fuel. The model takes into account things like: Flight time Cargo Weight Safety factors Airlines use software to make complex decisions, not rules of thumb.
10. 10. Software Should Rule Datacenters Too 10 Dont look at vCPU to Core ratios to determine host density. Look at a large set of metrics that effect workload performance. Such as: CPU provisioning ratios CPU utilization at VM level and host level ReadyQ And many more metrics Enter VMTurbo.
11. 11. 11 Key utilization metrics for VM
12. 12. 12 Key utilization metrics for host
13. 13. Supply & Demand 13 VMTurbo makes smart choices on how to best distribute workloads to drive up overall host densities. We do that by understanding: Demand for resources from the virtual infrastructure Supply of resources on the physical infrastructure VMs dont have access to all the CPUs they need to be performant? VMTurbo allocates more resources. Not enough supply to meet resource demand? VMTurbo allocates more resources. Operations Manager recommended actions to assure performance due to CPU congestion on host.
14. 14. Make Intelligent Decisions 14 Dont make resource allocation decisions based just on vCPU to CPU ratio. Let VMTurbo Use vCPU:CPU as one factor in many. Provide actionable advice. Automate many decisions. All in the name of managing the risk of overprovisioning in conjunction with other performance related factors.
15. 15. Author Matt Ray Senior Sales Engineer VMTurbo 15