Performance & VMmark : Co-scheduling SMP VMs in VMware ESX Server : Comments

RE: Co-scheduling SMP VMs in VMware ESX Server

Ken.Cline — Thu, 22 May 2008 03:39:49 GMT

A question that gets raised fairly frequently is "is it better to put vSMP VMs together on a host, or mix them with single VCPU VMs?" Based on the article above, I submit that - as long as you're not accumulating significant skew, it shouldn't make much difference.

Could you address how NUMA impacts CPU scheduling? And also, I've heard that pinning a vCPU to a pCore has a negative impact on the scheduler...can you comment?

Thanks!

Ken Cline
Technical Director, Virtualization
Wells Landers
VMware Communities User Moderator

RE: Co-scheduling SMP VMs in VMware ESX Server

drummonds — Tue, 27 May 2008 23:05:45 GMT

Hi, Ken,

I created a broader scheduling topic called "VMkernel Scheduler" that answers some of your questions. Since your questions are strictly co-scheduling questions, I figured that to be a better place to provide answers.

I haven't yet provided the supporting data for these claims but hope to do so by the time we've finished seeding content. That should take a couple of months. In the mean time, please trust me that I'm not lying on the claims I've made.

Scott

RE: Co-scheduling SMP VMs in VMware ESX Server

Ken.Cline — Thu, 29 May 2008 13:04:40 GMT

Thanks Scott, I'll go read the other doc, too!

Ken Cline
Technical Director, Virtualization
Wells Landers
VMware Communities User Moderator

RE: Co-scheduling SMP VMs in VMware ESX Server

Iwan Rahabok — Sat, 19 Jul 2008 00:30:22 GMT

Scott, it's e1 from Singapore (we met in Bangkok during the QBR).

When we relax it in 3.x, do you mean starting from 3.0, or a certain update of 3.0 (e.g. 3.0.2)?

In 3.5.x, did we relax it further? If yes, could you provide more details?

Will email you separately which customer asked me the question.

Tx
e1

RE: Co-scheduling SMP VMs in VMware ESX Server

man33taro — Wed, 15 Apr 2009 23:46:29 GMT

If we enable Hyper Threading, how vSMP work?
I heard that LCPU can be HEC(Hardware Execution Context?).
Is that right?
We can see it in the text I&C course from VMware.
If so, LCU fix this issue?
For instance,
There is only 2 LCPC(not PCPU)on 1 PCPU, 2vSMP VM can run with no waiting?