An administrator is troubleshooting a performance problem with a virtual machine (VM). The VM and ESXi host configuration is as follows:
The application which runs within the virtual machine is highly sensitive to memory latency, but has low processor utilization.
The virtual machine has 6 vCPUs.
The ESXi host CPU topology has 2 Physical CPU Sockets, each with 8 Logical CPUs.
The ESXi host CPU has Hyper Threading enabled.
The administrator would like to improve CPU performance for this VM. Other VMs on the host have no performance issues. Which action should the administrator
take to resolve the issue?
A.
Set the Advanced Parameter numa.vcpu.preferHT = TRUE in the virtual machine configuration file.
B.
Set the Advanced Parameter numa.vcpu.preferHT = FALSE in the virtual machine configuration file.
C.
Set the Advanced Parameter numa.PreferHT = 1 in the ESXi host configuration file.
D.
Set the Advanced Parameter numa.PreferHT = 0 in the ESXi host configuration file.
Explanation:
Explanation/Reference:
A is correct.
For memory latency sensitive workloads with low processor utilization or high interthread communication, use hyper-threads with fewer NUMA nodes instead of full physical cores spread over multiple NUMA nodes.
Configure virtual machines to use hyper-threading with NUMA.
https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2003582
The key to this question is looking at it from the VM. If this was asking about the host, the answer would be C. Frank gives a pretty detailed explanation: http://frankdenneman.nl/2016/08/22/numa-deep-dive-part-5-esxi-vmkernel-numa-constructs/
just 1 vm have problem. Others runs OK.
A