RE: [Xen-users] Question about the AMD Vs. Intel debate...

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

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Doug
> Sent: 27 October 2006 15:40
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] Question about the AMD Vs. Intel debate...
> 
> I'm just wondering now that both the Core 2 duo's and the AMD X2's
> both with virtualization support have been out for a while, 
> what everyone's
> opinion of them are?
> 
> Is one better than the other in certain areas? I'm looking to set up a
> proof of concept system and a general testing things out 
> system for running
> xen on. And frankly...the prices aren't really that different 
> anymore, so
> I can't simply choose one based on price.
> 
> What's the general feel (I know there are lots of loyalists 
> out there, but I
> want facts and numbers, not warm fuzzy feelings...)
> 
> I also know there are lots of other considerations, like 
> motherboard chipset
> support in xen, etc. So overall which platform is better...or are they
> basically the same? I'm concerned about power usage and heat 
> output, but I
> also want some bang for my buck.
> 
> I'm looking at the sub $200 range (so the core 2 duo 6300 or 
> the pentium D
> 940 or the athlon X2 4200 windosor core).
> 
> I've checked tomshardware, but all they have are charts 
> comparing relative
> performance doing windows stuff like playing music and 
> scanning for viruses.
> And even the number crunching benchmarks don't really tell me 
> which system
> will perform best running multiple virtual machines.
> 
> Anyway, I'm not trying to start a flame war or anything, just not sure
> which is the best route. Thought maybe someone out there 
> might have set
> up a system of each and tested them out or something and could give me
> some info.
> 
> Thanks,
> Doug
> 
> 
As you can see from my mail-address, I'm certainly biased... 

However, wearing my patented "objective-tin-foil-hat" to make me a bit
more unbiased, I'll try to say this:
There is VERY LITTLE technical "external" differences between the AMD
and Intel virtualization technologies, so from that perspective one
isn't noticably better than the other. 

So from a software architecture standpoint, the solutions to the
problems become very similar. This is why a large portion of the code
executed in the hypervisor for fully virtualized domains is 80-90% the
same, and most of the remaining 10-20% do the same thing in near enough
the same way, but because of the small differences that are between the
architectures, the code must be separate. When we started to introduce
the AMD architecture, we looked at doing a lower abstraction layer to
allow more code-sharing, but it turned out that it would both limit the
ability to use architectural differences, and it would cause some extra
code to be added in many places (calling a function to dig out one word
out of a memory location - and because it's a function-pointer, the code
could not be inlined either). So that idea was scrapped for a higher
abstraction layer that has more functionality in each function, which
means that a little bit more code is not in the shared files, but the
code is slightly faster and easier to follow (and it's possible to make
use of some of the arch. Differences that are in there). 

So, as a conclusion, both companies offer a pretty equal product when it
comes to virtualization.

I would of course recommend that you buy AMD... ;-)

--
Mats



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