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Questions tagged [vcpu]

72 questions
28
votes
4 answers

Best Practice: vCPUs per physical core

I am trying to find some documentation or best practice guides for virtualization with respect to provisioning vCPUs per physical core (of a CPU). If it matters, I am looking at vmWare for the virtualization implementation. For example, an Intel…
Dr. Watson
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18
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3 answers

Understanding the VMware ESXi limitations of the free Version

I am running an ESXi Vsphere Client Version 6.0.0 but with all the different documentation and changes I have trouble to understand my limitations. From the official documentation I see that my limit for physical CPU should be unlimited but I can…
RayofCommand
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12
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1 answer

KVM Host with 88 physical cores uses only 14 on 64 core Guest

I do have a server with 2 CPUs (22 Cores each plus HT). I created a KVM Guest with 64 allocated cores. When I run a compilation task the virtual machine shows all 64 cores at 100% (at moderate Disk I/O and memory usage) but on the physical machine…
HibikiTaisuna
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9
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4 answers

Virtualized CPU cores vs. threads

We've got a KVM host system on Ubuntu 9.10 with a newer Quad-core Xeon CPU with hyperthreading. As detailed on Intel's product page, the processor has 4 cores but 8 threads. /proc/cpuinfo and htop both list 8 processors, though each one states 4…
nedm
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9
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1 answer

Do CPU credits exist for c5d.large instances? And if not, why not?

I've been paranoid that the websocket feed I was listening to on a t3.micro instance was being inhibited by cpu steal time from other instances under the same hypervisor. So I switched over to a c5d.large instance and definitely noticed less…
randy
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8
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1 answer

Are vCPU the same as 1 Socket, or a single Core?

Currently I have a Hyper-v VPS with 2 (vCPU) processor. I would like to install SQL Server Express 2012 that has a limitation of 1 Socket or 4 Cores, whichever the lesser. My Question: Are vCPU's counted as a single core, or as sockets? or…
TreK
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7
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4 answers

How does the vCPU align with the CPU? (VM with more cores than the CPU has)

I have a VM running on vSphere 6.5.which has 24 vCPU's. The server has two physical cpu's (xeon e5-2699 v4) which have 22 cores and hyperthreading is enabled. How exactly are the vcpu's running on the physical cpu's? Would it be better to reduce…
user3235860
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2 answers

Multiple vCPUs or multiple identical VMs, which is better?

I am looking to upgrade one of our servers, an 8 core server running VMware Server 2. The VMs it runs are mostly web, file, and email servers; specifically, it runs three webservers, 2 email/file servers, and a few Jabber/XMPP Servers. When we…
Josh
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3 answers

VMware / SQL - physical vs logical cores - how many vCPUs to assign when HT is enabled

We have a ESX host: It has 2 CPU x 8 cores each, and HT enabled. So, total 16 physical cores or 32 logical cores. It has a single dedicated SQL VM on it (no other VMs run on this host), and it has 16 vCPUs assigned: and the SQL NUMA config looks…
d-_-b
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1 answer

AWS EC2 instance hyperthreading

I am currently doing some performance testing of web-apps that we have moved to AWS. One of the things we have noticed is that vCPU performance doesn't seem to be nearly as good as we'd expected. In fact, on a highly utilize single vCPU machine we…
zmcmahon
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1 answer

Oversubscription vs Over allocation of vCPU resources in vSphere

I'm trying to understand over allocation of vCPU compared to over subscription of vCPU. For the purposes of the question lets assume the host that I will be using has a 16 core Xeon(2.1Ghz). Based on my research over subscription is having VMs…
seelani
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1 answer

Modifying the number of VCPUs in a VMware VM

In ESXi, what is the automation/script (I expect it would be using PowerCLI somehow) approach to modify the number of VCPUs in a VM? In context, when using our kickstarts, RHEL won't install the SMP kernel unless there is more than one CPU on the…
warren
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3 answers

What does the vSphere 8 core maximum mean?

I'm configuring software that will need about 12 cores to run, but I am running it on a vSphere virtual machine, meaning that at most 8 (virtual) cores can be configured.[1] The physical machine that this will be running on has 24 cores available,…
mlissner
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Can the number of CPU cores be reduced for a CentOS virtual machine?

Our VMware admins tell me that we can add additional virtual CPU cores to our VM's, but they tell me that we can't reduce the number of virtual CPU cores. One recently stated, "CPU on the other hand is a bigger problem because while you can add CPU…
Will
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How to project / measure physical host wait with multi-core guests in ESXi

I’ve heard that if you have a guest with N virtual cores under ESXi, the hypervisor waits for N total logical processors on the host to become available simultaneously before delegating work from the guest to the hardware. Therefore, the advice is…
Chris Tonkinson
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