Some links on Hyperthreading, ESXi and vSphere
Posted by jpluimers on 2016/07/22
In case I bump into vSphere/ESXi machines that have hyper threading (HT) enabled:
- Short summary: HyperThreading: What is it and does it benefit ESXi? | VMXP.
- Extensive list of considerations: Tune ESXi Host CPU Configuration.
- Short list of configuration steps: Enable Configure or Disable Hyperthreading on Vsphere ESXi Hosts | RouteMyBrain.
- Back in 2010 you could already benefit from HT: Hyper-Threading on vSphere « vPivot.
- NUMA can benefit from using HT; in vSphere 4 you had to enable NUMA.preferHT for processor cache intensive work: Optimizing vSphere for Hyper-threading « vPivot.
- vSphere 4, 5 and up are HT aware: virtualTodd’s Big Blog: Enabling HyperThreading for vSphere Servers.
- Intel HyperThreaded CPU cores do not count towards the CPU resources: intel – CPU Resource pool with and without hyperthreading in vmware esx/esxi – Server Fault.
- Pros and Cons: Use Hyperthreading in ESX or not? | The VMguy.
- Extensive PDF: Performance Best Practices for VMware vSphere 5.0.
- Great analysis atvia Dasher Blog | Will Hyper-Threading Improve Processing Performance?. including a list of potential cons you should test:
- the server has more than two sockets,
- the server has a large number of physical cores,
- the operating system is not hyper-threading aware (example: Windows Server 2003),
- the application is single-threaded or does not handle multiple threads efficiently,
- the application is already designed to maximize the use of the execution units in each core, or
- the application has a very high rate of memory I/O.
- Great discussion in the comments; always measure! Hyper-Threading Gotcha with Virtual Machine vCPU Sizing – Wahl Network.
–jeroen
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