Comparison between KVM and VMWARE

[falves1]

I am doing some comparative research betweer KVM and Vmware Vsphere
4.1. For a client virtual machine, Vmware exposes these cpu features
not found in a KVM virtual machine:
acpi
aperfmperf
arch_perfmon
bts
constant_tsc
dts
nonstop_tsc
pat
pebs
ss
ssse3
tsc_reliable
unfair_spinlock
vme

The question is, does it matter or not? I cannot find a fundamental
difference in performance, at least for running virtual versions of
Asterisk, which do heavy transcoding (Linux)

Federico

 

[tom]

This list is wrong.

 

[falves1]

This list is right. I logged into two Linux 64 virtual machines, on two identical servers, one with KVM and one with Vshpere 4.1m and did cat /proc/cpuinfo
KVM Virtual machine (Debian Squeeze):
flags : fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pse36 clflush mmx fxsr sse sse2 syscall nx lm rep_good pni cx16 hypervisor lahf_lm
Vmw:
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx lm constant_tsc arch_perfmon pebs bts rep_good tsc_reliable nonstop_tsc aperfmperf unfair_spinlock pni ssse3 cx16 hypervisor lahf_lm

The KVM is from RHEL 6.1, which might not be the same as the latest version of Proxmox, but I ignore of the CPU flags changed.

I can give you access to the servers via SSH so you may check.

 

[l.mierzwa]

KVM exposes by default only subset of cpu features that are supported by most of cpu versions that support virtualization so that after You live-migrate VM from one host to another it does still work on new host cpu. If You got same cpu on every host You can enable all the feature or only those You need (like ssse3 for multimedia apps).
http://www.linux-kvm.org/page/Tuning_KVM

 

[tom]

we do not test rhel61 here, this is a Proxmox forum.

cpu features provided to the guest also depend on the -cpu argument. e.g. you can pass the host cpu type to the guest by adding the following line to your /etc/qemu-server/VMID.conf.

args: -cpu host

 

[tylerdurden81]

There are many problems with running asterisk with Vmware. You will get choppy audio on IVR recording and Voicemail. Asterisk works very well under KVM and OpenVZ. This is why we went to Proxmox.

I am doing some comparative research betweer KVM and Vmware Vsphere
4.1. For a client virtual machine, Vmware exposes these cpu features
not found in a KVM virtual machine:
acpi
aperfmperf
arch_perfmon
bts
constant_tsc
dts
nonstop_tsc
pat
pebs
ss
ssse3
tsc_reliable
unfair_spinlock
vme

The question is, does it matter or not? I cannot find a fundamental
difference in performance, at least for running virtual versions of
Asterisk, which do heavy transcoding (Linux)

Federico

 

[falves1]

Do you mean Asterisk under KVM or under OPenVZ?

 

[tylerdurden81]

Works well in both. There is a PBX In A Flash container already made for OpenVZ. Running a native PBX IN A Flash kernel in KVM works fine also.