Comments on: KVM Performance

By: KVM -all the way

KVM -all the way — Tue, 23 Feb 2010 13:46:12 +0000

KVM is no doubt the best virtualization solution. Period.

Enough nonsense with these fake VMware propaganda artists.

we run KVM in 32 processor numa-smp machine and vmware is no-where in the picture in terms of performance , flexibility & cost.

Vmware fools get a life –open your insight. Your loser VCP certifuication is no good when it comes to kernal programmers & enthusiasts.

By: Scott

Scott — Thu, 10 Dec 2009 01:47:57 +0000

I am glad to see that they published a consolidated workload. SPECjbb is a likely choice, as it does not do any IO at all. ESX runs it at near-native speeds on SPECjbb. But, believe me, showing even this workload is better than nothing!

You say that KVM runs “pretty well” for you. Have you quantified this? I would love to hear what you have done.

By: Trung

Trung — Mon, 07 Dec 2009 18:35:01 +0000

Following a study posted on principledtechnologies, Redhat’s KVM works pretty well for me with 1.5x cpu overcommit and 1.5x memory overcommit (ksm)

By: David A

David A — Tue, 06 Oct 2009 15:59:17 +0000

An advocate for any technology can cite use cases that tout how their solution is better. Since Scott works for VMware it is not surprising that the results are slanted in VMware’s favor. What is disappointing is the lack of details on the test setup, versions, etc for others to reproduce the results.

I am an advocate of the technology in general — and a user of both ESX and KVM. There are a ton of valid and relevant use cases for both. As for performance, there are a lot of examples where KVM is far superior to ESX. One example is linux guests based on the 2.4 kernel (e.g., RHEL 3) where the guest has 2GB or 4GB of RAM. The performance degradation of ESX on DL380 G5 is staggering (2.4 kernels are very active with page scanning). With KVM’s out-of-sync shadow table implementation that was added in August/September 2008, KVM runs these older guests just fine — in fact for my specific test the performance loss can be kept under <10%. I have others, but this one is easy for anyone to reproduce. Just install CentOS 3 in a guest with 2 or 4 cpus and 2-4 GB of RAM and then run whatever benchamrk suits your fancy

Of course, one can argue that 2.4 kernels are old (ignore the argument for now of how virtualization allows the continued deployment of older guests), but then so is a DL380 G5. As I recall those came out some time 2006. ESX and its binary translation is certainly optimized for such older setups and given that will outperform hardware based design like KVM in a number of use cases.

How about a comparison on newer hardware — say a DL380 G6 with 2 quad-core E5540 processors and 24 GB of RAM (3×4GB = 12 GB per processor)? Now you have a more relevant use case involving modern hardware. ESX 4.0 will leverage the EPT in the procesors. Oh, and be sure to publish all the relevant details on the test setup. Test results are meaningless of others cannot reproduce.

By: Scott

Scott — Sat, 03 Oct 2009 01:25:18 +0000

David’s comment (number three) is fair. I am going to remove the results and let Red Hat (or any KVM evangelist) speak for their own product with a known benchmark.

Would anyone care to guess when that might happen?

By: David

David — Thu, 01 Oct 2009 17:00:24 +0000

Aren’t you demonstrating exactly the behaviour you condemn with vendor benchmarks.
VMware prohibits people publishing competitive benchmarks with the justification that they need to be conducted in a fair manner and audited, which makes sense.

Here you are publishing exactly the kind of FUD sudo-benchmark that you complain to others about.

By: Miker

Miker — Thu, 01 Oct 2009 14:34:35 +0000

Could you post details of the setups?

By: Ian Woodstock

Ian Woodstock — Thu, 01 Oct 2009 00:49:58 +0000

Are you going to publish any real details. I just see “KVM”, that’s like saying “Linux”

What distribution, what version, what guests, what tuning, did you install PV drivers in the KVM guests, did you install vmware tools in the VMware guests.
What management tool did you use to configure and set this up – you mention Red Hat in the article but did you actually use their management tool?

There’s so little detail in here it’s obviously a very biased piece.