RE: [Xen-users] Has VMware better performance than Xen 3?

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Jose Ernesto Suarez
> Sent: 15 March 2007 15:52
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Has VMware better performance than Xen 3?
> 
> Hi list!
> I´m a newbie on virtualization but i have this question.
> 
> Actually I was developing  a virtualization schema on my job, i find  
> useful the Vmware,Xen and KVM tools to make my probes..
> 
> The scenario is very simple , only one phisical machine running  
> Debian Etch and two kernels, the binary 2.6.18-xen and the vanilla  
> 2.6.20.1 running vmware...on booth, i have installed the WxpSP2 and  
> no other software that the PerformanceTest 6.1.The machine runs on  
> core2 6600 with 4gb 800Mhz DDR2 and intel ICH8 and 965 chipset,
> 
> The results:
> vmware is a bit better tan xen on cpu operations and much better on  
> disk operations (600%).In 2D graphic performance is incredibily more  
> faster...(varies on >42000%< and 300%...)In memory probes, booths  
> have the same performance.
> when i probe to use 2 vcpus on Xen I get a bit of  poor performance...

Disk IO is dependant on the driver architecture. VMWare uses para-virtual 
drivers (or in other words "special drivers for virtualization"), which is 
possible in Xen too, but they are not available in the open source version of 
Xen. 

Also, for some types of operations, the binary translation that VMWare uses is 
faster than the intercepts of the individual instructions in the Xen 
implementation. This is because if you do binary translation, multiple 
consecutive instructions that need hypervisor intervention could be intercepted 
at once. It's also very likely that the call from guest to hypervisor is a bit 
slimmer on VMWare - this is because the hardware implementation (particularly 
in the first generation of HW virtualization) is very memory intensive, and 
it's saving EVERYTHING and restoring EVERYTHING every time the processor jumps 
between the guest and the hypervisor. With some clever tricks in software, you 
can avoid saving the whole world on certain calls to the hypervisor. 

It's also quite likely that some of the code in the hypervisor is a little bit 
less than optimal. AMD at least hasn't spent much effort optimizing the 
hypervisor implementation in Xen - I don't think Intel has done much either. 

Using both cores on a dual core system in Xen with Dom0 having to "fight DomU" 
to get CPU-time is probably not the most optimal way to set your system up. 

> 
> 
> My question:
> Is VMware more faster than Xen?

Sometimes. 

> how do I make my xen installation more faster?

You could download the XenEnterprise (XenExpress) to get PV drivers. That 
should speed up the disk access (and network access). 
> 
> Thanks,
> 
> 
> 
> 
> 
> 
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