25
votes
Accepted
Do CPU credits exist for c5d.large instances? And if not, why not?
CPU credits only apply to T2/T3 instances. Each T2/T3 instance accumulates some CPU credits per second and also when it's in use (i.e. not "idle") it spends these CPU credits. When it runs out of ...
- 24.5k
15
votes
Accepted
Understanding the VMware ESXi limitations of the free Version
Those two stats you mention are different; it's 8 virtualised CPUs per VM and 2 physical CPU sockets that they're talking about - not the same thing. BTW if you're going with the free version have a ...
- 101k
14
votes
Understanding the VMware ESXi limitations of the free Version
Free version Hypervisor (Esxi) Version 6.0
2 (physical) CPU limit
No Ram limit (removed since 5.5)
Hypervisor Spec
Number of cores per physical CPU: No limit
Number of physical CPUs per host: No ...
- 3,043
12
votes
Accepted
KVM Host with 88 physical cores uses only 14 on 64 core Guest
There was a vCPU pinning in the XML which doesn't appear in virt-manager -.- I removed it via
for i in {0..63}; do sudo virsh vcpupin $kvmdomain $i r --config; done
and removed the line in the XML-...
- 273
6
votes
Accepted
AWS EC2 instance hyperthreading
I received confirmation from Amazon that a vCPU is in fact a single hyperthread on a single core.
On a side note, this was news to the software vendor we were working with (one of the biggest ...
- 211
5
votes
Can the number of CPU cores be reduced for a CentOS virtual machine?
You can change the virtual machine dimensions (RAM, CPU, socket count) without reconfiguring the operating system. CentOS will handle this fine.
You cannot do this without a poweroff/reboot, though. ...
- 197k
5
votes
Accepted
virsh vcpu_period and vcpu_quota
quota
The optional quota element specifies the maximum allowed bandwidth(unit: microseconds). A domain with quota as any negative value indicates that the domain has infinite bandwidth, which means ...
- 66
4
votes
How vCPUs are calculated?
Your vendor is selling you a simple story to explain something that can be complicated, but theirs is a bit off.
For starters: Hyper Threading does not give you extra cores, it just abstracts task ...
- 68.7k
4
votes
Accepted
How can I keep a third-party cloud provider accountable for guest VM performance?
It's perfectly possible; pretty much anything can be specified in a Service Level Agreement (SLA). Since your provider is a smaller one, I would say you have a somewhat better chance of getting this ...
- 79.6k
4
votes
Accepted
Virtualization: vCPU pinning with Hyperthreading Host CPU?
You may be overthinking this.
The manual assignment of cores here could actually result in lower performance. In the VMware world, we don't do this unless there are very specific requirements, but ...
- 197k
4
votes
Understanding the VMware ESXi limitations of the free Version
When you apply the ESXi 6 free license, it appears :
Product : VMware vSphere Hypervisor Licenced 6 for 2 physical CPUs ( unlimited cores per CPU)
Product features:
Up to 8 -way virtual SMP
...
- 41
3
votes
Can the number of CPU cores be reduced for a CentOS virtual machine?
Reducing the number of CPU cores merely requires that the VM be stopped. It can't be done while the VM is running. Perhaps that is what they meant? I suppose it's also possible that they don't know ...
- 242k
3
votes
Accepted
Best VMWare Esxi CPU Resource Allocation Policy
My suggestion was to assign all 88 cores to each VM, and give each
1/11 of CPU power reserved.
PLEASE don't do this, please - presumably you've not been on an vSphere courses right?
Don't use any ...
- 101k
3
votes
How does the vCPU align with the CPU? (VM with more cores than the CPU has)
A single VM must never have more virtual CPUs than logical physical cores that are available.
With Hyperthreading enabled you are at 44 logical physical cores, so this should be fine. However, this ...
- 22.5k
2
votes
Accepted
CPU frequency governor for virtualized guest in VMware
CPU Core power management is a function that can be owned by the system/BIOS on its own but usually it's a collaborative effort with the OS, in an Intel world this is done via Speedstep extensions, ...
- 101k
2
votes
Xen reduce VCPU
This is a similar case where xm list failed to list configuration changes:
https://serverfault.com/a/484904/337307
The issue occurs because a configuration file that is generated when the VM is ...
- 3,137
2
votes
Microsoft Azure threads per core
I hope you can help with the following,
A – SERIES (A0 -A7)
CPU: Intel Xeon® E5-2630 v3 @ 2.4 GHz
Cores / Threads : 8 / 16, L3 Cache : 20 MB, Data Width : 64 bit
A – SERIES (A8-A11)
CPU: ...
- 186
2
votes
Accepted
Microsoft Azure threads per core
On Azure, A Vm core gets for a physical core.
F-Series VMs are based on the 2.4 GHz Intel Xeon® E5-2673 v3 (Haswell) processor, which can achieve clock speeds as high as 3.1 GHz with the Intel Turbo ...
- 3,583
2
votes
How to project / measure physical host wait with multi-core guests in ESXi
There's a lot of poor VMware advice and defunct best-practices out there.
Even VMware's website promotes outdated solutions due to poor SEO.
But the right way to assess this is to use a tool like ...
- 197k
2
votes
How does the vCPU align with the CPU? (VM with more cores than the CPU has)
1) Hyperthreaded cores aren't real cores, and shouldn't be counted as such. Estimates vary, but I've seen figures that enabling HyperThreading gives you as low as 10-30% additional performance in ...
- 3,486
2
votes
Azure VM Core vs vCPU
This is down to whether you get a real core or virtual core.
Older VM SKUs, and some specialised SKU's like H series have a 1 to 1 mapping between physical cores in the host machine and cores in the ...
- 38.6k
2
votes
Accepted
Google compute - Less vCPUs high IOPS vs More vCPUs low IOPS
Reduced memory reduced your cache hits. Assuming you did not change the database's memory configuration, previously it was OS file system buffers which serviced those reads.
Relation of system memory ...
- 31.5k
2
votes
Accepted
KVM with 1 vCPU has CPU load above 1
Load average is proportional to the number of tasks running or ready to run. It does not reflect the number of CPUs.
Indirectly, you can use this to calculate a utilization metric. What the ratio of ...
- 31.5k
1
vote
How does the vCPU align with the CPU? (VM with more cores than the CPU has)
I can't think of a situation where you'd want a single VM to have more vCPUs allocated than there are physical cores in a server.
Benchmark your workload with the current VM configuration, and then ...
- 5,011
1
vote
Accepted
aws ec2 t2.small vs t2.medium CPU performance
Your server will be able to do more work in parallel. If it's just serving static web pages I wouldn't expect much difference. If it's executing php on a loaded server then I would expect some ...
- 31.5k
1
vote
Maximum number of virtual CPU for Windows 7/10 virtual machine
The maximum specifications of the ESXi hosts are well documented. For example, from the document for ESXi 6.0:
Virtual CPUs per virtual machine (Virtual
SMP)
128
However, due to the way VMware ...
- 22.5k
1
vote
Accepted
How to project / measure physical host wait with multi-core guests in ESXi
Hyper-threading is lying about the number of cores to get a few percent boost. You do not have 24 cores, you have 12. Although, I would feel a little better about fully using those 12 cores for guests ...
- 31.5k
1
vote
Accepted
Decreasing CPU allocation to running Guest Windows server
The hotplug command you're trying to run requires the guest agent to co-operate to complete the unplug action. In fact it is not actually doing an unplug at all - it is simply asking the guest OS to ...
- 1,598
1
vote
Oversubscription vs Over allocation of vCPU resources in vSphere
You're trying to understand the problem from the most difficult end, CPU resources. Approach it from Memory instead and it's a bit easier to understand.
The host has x amount of memory, and the host ...
- 3,486
1
vote
VMware / SQL - physical vs logical cores - how many vCPUs to assign when HT is enabled
Generally, keeping assigned vCPUs no more than the physical cores (ignoring HT) is playing it safe. You have 2 physical CPUs with 8 core each (although I remember the E5-2667 having 6) - that means 16 ...
- 3,048
Only top scored, non community-wiki answers of a minimum length are eligible