I am working on a setup where I am running a Ubuntu VM on a Fedora 18 host using QEMU/KVM and libvirt. Now I have pinned 2 vCPUs to my VM. I can see the pinned vCPUs using virsh. But, is there any other way to find that out? Ideally, I want to write a function which will return the number/id of pinned vCPUs.
You can use element in domain XML to determine which pinned CPUs for which vcpu. see section CPU Tuning. By default, the vcpu is pinned to all physical CPUs.
For example:
<cputune>
<vcpupin vcpu="0" cpuset="1-4,^2"/>
<vcpupin vcpu="1" cpuset="0,1"/>
</cputune>
Related
I need to restrict an app/deployment to run on specific cpus only (say 0-3 or just 1 or 2 etc.) I found out about CPU Manager and tried implement it with static policy but not able to achieve what I intend to.
I tried the following so far:
Enabled cpu manager static policy on kubelet and verified that it is enabled
Reserved the cpu with --reserved-cpus=0-3 option in the kubelet
Ran a sample nginx deployment with limits equal to requests and cpu of integer value i.e. QoS of guaranteed is ensured and able to validate the cpu affinity with taskset -c -p $(pidof nginx)
So, this makes my nginx app to be restricted to run on all cpus other than reserved cpus (0-3), i.e. if my machine has 32 cpus, the app can run on any of the 4-31 cpus. And so can any other apps/deployments that will run. As I understand, the reserved cpus 0-3 will be reserved for system daemons, OS daemons etc.
My questions-
Using the Kubernetes CPU Manager features, is it possible to pin certain cpu to an app/pod (in this case, my nginx app) to run on a specific cpu only (say 2 or 3 or 4-5)? If yes, how?
If point number 1 is possible, can we perform the pinning at container level too i.e. say Pod A has two containers Container B and Container D. Is it possible to pin cpu 0-3 to Container B and cpu 4 to Container B?
If none of this is possible using Kubernetes CPU Manager, what are the alternatives that are available at this point of time, if any?
As I understand your question, you want to set up your dedicated number of CPU for each app/pod. As I've searched.
I am only able to find some documentation that might help. The other one is a Github topic I think this is a workaround to your problem.
This is a disclaimer, based from what I've read, searched and understand there is no direct solution for this issue, only workarounds. I am still searching further for this.
i have question about KVM i could not find any satisfying answer in the net about.
Lets say i want to create 3 virtual machines on a host with 2 CPUs. I am assigning 1 cpu to 1 virtual machines. The other 2 virtual machines should be sharing 1 cpu. If it is possible i want to give 1 vm 30 % and the other one 70% of the cpu.
I know this does not make much sense but i am curious and want to test is :-)
I know that hypervisors like onapp can do that. But how do they do it?
KVM represents each virtual CPU as a thread in the host Linux system, actually as a thread in the QEMU process. So scheduling of guest VCPUs is controlled by the Linux scheduler.
On Linux, you can use taskset to force specific threads onto specific CPUs. So that will let you assign one VCPU to one physical CPU and two VCPUs to another. See, for example, https://groups.google.com/forum/#!topic/linuxkernelnewbies/qs5IiIA4xnw.
As far as controlling what percent of the CPU each VM gets, Linux has several scheduling policies available, but I'm not familiar with them. Any information you can find on how to control scheduling of Linux processes will apply to KVM.
The answers to this question may help: https://serverfault.com/questions/313333/kvm-and-virtual-to-physical-cpu-mapping. (Also that forum may be a better place for this question, since this one is intended for programming questions.)
If you search for "KVM virtual CPU scheduling" and "Linux CPU scheduling" (without the quotes), you should find plenty of additional information.
Is it possible to build a standalone Service Fabric cluster where Microsoft Nano is used as nodes?
I presume you mean for on-premise deployment. If it is then the answer is no as the minimum requirement wont be met.
https://learn.microsoft.com/en-us/azure/service-fabric/service-fabric-cluster-standalone-deployment-preparation
Prerequisites for each machine that you want to add to the cluster:+
A minimum of 16 GB of RAM is recommended.
A minimum of 40 of GB available disk space is recommended.
A 4 core or greater CPU is recommended.
I was looking for an answear but didn't find one.
I'm trying to create a new VM to develop a web application. What would be the optimal processor settings?
I have i7 (6th gen) with hyperthreading.
Host OS: Windows 10. Guest OS: CentOS.
Off topic: RAM that should I give to VM should be 50% of my memory? Would it be ok? (I have 16GB RAM)
Thanks!
This is referred to as 'right-sizing' a vm, and it is dependent on the application workload that will run inside it. Ideally, you want to provide the VM with the minimum amount of resources the app requires to run correctly. "Correctly" is subjective based upon your expectations.
Inside your VM (CentOS) you can run top to see how much memory and cpu % is being used. You can also install htop which you may find friendlier than top.
RAM
If you see a low % of RAM being used, you can probably reduce what you're giving the VM. If you are seeing any swap memory used (paging to disk), you may want to increase the RAM. Start with 2GB and see how the app behaves.
CPU
You'll may want to start with no more than 2vCPUs, checkout top to see how utilized the application is under load, and then make an assessment for more/less vCPUs.
The way a hosted hypervisor (VMware Workstation) handles guest CPU usage is through a CPU scheduler. When you give a vm x number of vCPUs, the VM will need to wait till that many cores are free on the CPU to do 'work'. The more vCPUs you give it, the more difficult (slower) it will be to schedule. It's more complicated than this, but I'm trying to keep it high level. CPU scheduling deep dive.
I have been trying to run a VM on some particular cpu cores. Now the thing is I can set cpuset with virt-install and that will reflect in VM's XML and it will define the affinity. But what about cpuset.cpus? That is inherited directly from the parent. Is there any way to set it when launching the VM? I mean, when I give the command virt-install, is there any option that can set cpuset.cpus dynamically?
virt-install doesn't support pinning particular VCPUs to host's CPUs. For this you have to use:
either GUI tool virt-manager
or edit the domain XML using virsh edit <domain> and set the pinning according to CPU tuning options