CPU performance of proxmox KVM guests

RodinM

Active Member
Aug 1, 2011
70
0
26
Hello,
How can I correctly check KVM guests' cpu performance in the proxmox environment?
I suspect that my VM's (windows guests) have much lower cpu performance than identical physical machines.

I measured the cpu performance with the built-in benchmark tool of 7zip archiver (one thread). The test was run under windows 7 guest (2 core, 2 cpu , 2GB RAM). The host server has 2 X Intel Xeon CPU E6510 (4 cores each with HT). All other VM's were powered off during testing.
The result (common rating) is 1260 MIPS.

I compared it with my "working horse" on virtualbox (windows 7 - 1cpu, 3GB RAM) with the same settings of 7zip archiver. The host machine has Intel Core i5 (4 cores).
It gave me the result (common rating) 2960 MIPS
Is it correct to measure the performance such way?
 
Do you have tried with cpu=host as cpu model ?

It's possible that 7zip bench use some features of processor to speedup things.


I tried this (I think you meant the same)
http://pve.proxmox.com/wiki/Allow_Guests_Access_to_Host_CPU
I added "args: -cpu host"


to the VM config. Then stopped and started the VM again

It had no effect.

- - - Updated - - -

I tried to rate the windows 7 guest with its own benchmark. It showed 4.6 scores for the CPU.
I think it is also not very good result for the 4 core machine
 
I tried adding the option
"args: -cpu host" to the VM config
It had no effect.
I tried to rate the VM with its built-in benchmark tool (windows 7 rating)
It gave 4.6 scores for the CPU.
I think it is also not a very good result for the 4 core VM (2 cpu x 2 core)
 
Uhm... what about "CPU Units"? Default is "1000" for each VM.

This could be the reason for "much lower" cpu-power.

You can check your CPU-"CPU-Units"-Power with "vzcpucheck".
For me it say's: "Power of the node: 999990".
Foe me - i spent every VM some "Units" and most (200.000) for the SBS - no performance-problems.
You can raise the value via .conf-file oder via the Webgui - give a try :)

---
EDIT:

This post explains "cpu-units": http://forum.proxmox.com/threads/889-CPU-questions
 
Hello,
How can I correctly check KVM guests' cpu performance in the proxmox environment?
I suspect that my VM's (windows guests) have much lower cpu performance than identical physical machines.

I measured the cpu performance with the built-in benchmark tool of 7zip archiver (one thread). The test was run under windows 7 guest (2 core, 2 cpu , 2GB RAM). The host server has 2 X Intel Xeon CPU E6510 (4 cores each with HT). All other VM's were powered off during testing.
The result (common rating) is 1260 MIPS.

I compared it with my "working horse" on virtualbox (windows 7 - 1cpu, 3GB RAM) with the same settings of 7zip archiver. The host machine has Intel Core i5 (4 cores).
It gave me the result (common rating) 2960 MIPS
Is it correct to measure the performance such way?

So basically you are comparing a single core from a 3 year old Xeon 1.73Ghz CPU vs a single core from an i5? Which i5 are you using?

In my experience with i5s and Xeon CPUs the figures look correct.
 
Uhm... what about "CPU Units"? Default is "1000" for each VM.

This could be the reason for "much lower" cpu-power.

You can check your CPU-"CPU-Units"-Power with "vzcpucheck".
For me it say's: "Power of the node: 999990".
Foe me - i spent every VM some "Units" and most (200.000) for the SBS - no performance-problems.
You can raise the value via .conf-file oder via the Webgui - give a try :)

I've just tried this with a Windows 2003 KVM and adjusting it from 1000 - 2000 - 10000 - 100000 - 200000 made no difference to CPU performance and also the vzcpucheck showed no difference - it always showed 1000 usage. (The KVM was shutdown, and the .conf file was edited, saved and the KVM was booted.)

From my understanduing this only made a difference for OpenVZ containers?
 

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