Hello newsgroup,

I've been trying to do some research on XEN (or other virtualization
platforms(?))

What I'd like to do is:

[HOST (linux)]
<linux>
<windows>
<freebsd>
<other_linux>
<other_linux>
...

Where a single, stripped down slackware box serves as a host operating
system and each "real" computer is virtualized some how. All the work
will be done in these virtual machines.

Most of the time, most of these virtual machines won't actually be
run (and in many cases, what I really want is a BSD jail, heck, even
plain old chroot will work) but not always.

My understanding is that with certain processors it is possible to
run a virtual machine with native performance (and be able to run
windows / freebsd)

I'm probably going to have to purchase a computer for this, this is
where I'm struggling..

All the docs I've seen have told me how to tell if my existing CPU has support,
but I can't seem to find a good list of AMD processors with virtualization
support BEFORE deciding.

I don't want to find out it doesn't after I buy the silly thing!

Anyone know of such a list? (PLEASE don't say opteron, I can't afford it!)

Second question.. is it possible to allocate a monster sized swap partition?
reason I ask is that with UML anyway (only virtualization I've had experience
with) I ran into trouble allocating a swap file.

Turned out, I was spending a huge amount of CPU time because the host was
sync'ing a virtual swap device on an ext3 filesystem.

I'd really like to avoid this problem if possible and my strategy
at this point anyway, is to allocate say, 30+GB of "swap space" then mount
/tmp as tmpfs and finally, but these virtual swap devices as /tmp/swap.dsk

However, last time I tried that, I had some hard drive corruption. Anyone here
ever create monster sized swap partitions like that (and KEEP it for a long
period of time)? (or, have a better idea perhaps?) When I did it, the corruption
didn't appear until several weeks later.


The big question though, how to find a list of AMD processors that support
the virtualization. (I'm fond of AMD and want to stick with them. :-) )

AMD's site doesn't seem to have a list (or at least, none that I could find)

Even a definate list of AMD CPU's that DON'T have it would be helpful.

Thanks!

Jamie
--
http://www.geniegate.com Custom web programming
Perl * Java * UNIX User Management Solutions

On Aug 3, 1:09 am, nos...@geniegate.com (Jamie) wrote:
> I've been trying to do some research on XEN (or other virtualization
> platforms(?))

Actually, you might be onto something. Choose one or more apps and
see if they have such a list, or if their mailing list/etc members
would know of one. They would probably be able to point you in the
right direction.

Jamie wrote:

> All the docs I've seen have told me how to tell if my existing CPU has support,
> but I can't seem to find a good list of AMD processors with virtualization
> support BEFORE deciding.

There was a required feature in the CPU, and as far as I can recall this
feature (don't remember it's name, but you should easilly find it in the XEN
docs) you can only find in the 64bit AMD CPUs, I would recommend you go for an
AM2-socket. I have to make a reservation against the Sempron CPUs, as I'm not
sure they have the needed feature.


> Second question.. is it possible to allocate a monster sized swap partition?
> reason I ask is that with UML anyway (only virtualization I've had experience
> with) I ran into trouble allocating a swap file.

As far as I know XEN don't have any limitation on swap, you can setup it quite
in the same manner as in a normal Linux environment.


> Turned out, I was spending a huge amount of CPU time because the host was
> sync'ing a virtual swap device on an ext3 filesystem.

XEN allows you to access a real swap, swap files is always a bad thing to use,
just look at microsoft.


> I'd really like to avoid this problem if possible and my strategy
> at this point anyway, is to allocate say, 30+GB of "swap space" then mount
> /tmp as tmpfs and finally, but these virtual swap devices as /tmp/swap.dsk
>
> However, last time I tried that, I had some hard drive corruption. Anyone here
> ever create monster sized swap partitions like that (and KEEP it for a long
> period of time)? (or, have a better idea perhaps?) When I did it, the corruption
> didn't appear until several weeks later.

The question is really, do you need that much, today many just use 1*RAM for
swap. Even if you run a load of different things, you hardly will use all
those at the same time and run a million of programs on all the OSes.


> I'm fond of AMD and want to stick with them. :-)

Even if the Intel is a better CPU on Laptops (better switching between
frequencies), AMD is a lot better on desktop environments, at least I think so
after I been able to compare my computer at work (Intel Dual Core) and my
computers at home (AMD, PowerPC and Sparc), I wouldn't go for Intel even if
they are supposed to be a lot faster, you get a smother desktop with AMD IMHO.


> AMD's site doesn't seem to have a list (or at least, none that I could find)

No, I don't AMD will list anything like that, you have to check the XEN manual
for required feature and then check the CPUs yourself, but those AM2-socket
are a good bet, you should be able to get a decent CPU to run XEN for around
80 euros.

--

//Aho

In <5hh82nF3jlm88U1@mid.individual.net>,
"J.O. Aho" <user@example.net> mentions:
>Jamie wrote:
>The question is really, do you need that much, today many just use 1*RAM for
>swap. Even if you run a load of different things, you hardly will use all
>those at the same time and run a million of programs on all the OSes.

You're right, I was just thinking if I mount /tmp as 'tmpfs' I could use the
swap to hold temp files, too. (I should clarify, the "monster swap" would
be allocated on the HOST operating system)

Last time I tried this, I ended up creating several <1GB partitions because
there was some sort of limitation within the linux kernel. (corrupting hard
drive stuff)

>Even if the Intel is a better CPU on Laptops (better switching between
>frequencies), AMD is a lot better on desktop environments, at least I think so
>after I been able to compare my computer at work (Intel Dual Core) and my
>computers at home (AMD, PowerPC and Sparc), I wouldn't go for Intel even if
>they are supposed to be a lot faster, you get a smother desktop with AMD IMHO.

I've still got an AMD 700MHZ running here. Works perfect, comparing MHZ to
performance, I'm really impressed with them. (probably the processor cache
and the fact that I compile stuff for that specific processor when I can.)

It's just that I don't want a dozen cheap machines taking up space & using
electricity.

>> AMD's site doesn't seem to have a list (or at least, none that I could find)
>
>No, I don't AMD will list anything like that, you have to check the XEN manual
>for required feature and then check the CPUs yourself, but those AM2-socket
>are a good bet, you should be able to get a decent CPU to run XEN for around
>80 euros.

Yea, I did check the docs, from what I've read, they don't actually list the
processors supporting it, they just tell you how to determine if your
existing CPU has support for it. (which doesn't do me a whole lot of good
since I'm planning on buying a CPU specifically FOR their application)

AM2 and avoid Sempron eh?

Sounds like a plan!

Any other 64-bit, AM2 socket processors I should avoid that you know of?

Thanks!

Jamie
--
http://www.geniegate.com Custom web programming
Perl * Java * UNIX User Management Solutions

Jamie wrote:

> I've still got an AMD 700MHZ running here. Works perfect, comparing MHZ to
> performance, I'm really impressed with them. (probably the processor cache
> and the fact that I compile stuff for that specific processor when I can.)

In fact Intel usually have twice as large cache than what AMD has, and I think
the Dual Core had a cache that the both cores shared.


> It's just that I don't want a dozen cheap machines taking up space & using
> electricity.

I'm not sure on which you save power/electricity on, quite often the new CPUs
require quite a lot of Ws, I think my laptops CPU draws more than what my
whole file server does.


>>> AMD's site doesn't seem to have a list (or at least, none that I could find)
>> No, I don't AMD will list anything like that, you have to check the XEN manual
>> for required feature and then check the CPUs yourself, but those AM2-socket
>> are a good bet, you should be able to get a decent CPU to run XEN for around
>> 80 euros.
>
> Yea, I did check the docs, from what I've read, they don't actually list the
> processors supporting it, they just tell you how to determine if your
> existing CPU has support for it. (which doesn't do me a whole lot of good
> since I'm planning on buying a CPU specifically FOR their application)
>
> AM2 and avoid Sempron eh?
>
> Sounds like a plan!
>
> Any other 64-bit, AM2 socket processors I should avoid that you know of?

A quick check with google at Xen-maillist, got that the feature required is
SVM and with help of google again, I got the following link

http://en.wikipedia.org/wiki/X86_vir...on_.28AMD-V.29

Where it says:

AMD virtualization (AMD-V)

AMD's virtualization extensions to the 64-bit x86 architecture is named AMD
Virtualization, abbreviated AMD-V. It is still referred to as "Pacifica", the
AMD internal project code name.

AMD-V is present in all K8 AMD (Athlon 64) processors from stepping "F" and
all newer processors support AMD-V technology. This applies for all current
Socket AM2 and Socket F processors.

So AM2 seems to be safe bet.

Another reason why not use Sempron is that it has always less cache than the
X2 and you will want to have large cache, you could go for one X2 with 2x1MB
cache, but that will more or less double the price for the CPU.


--

//Aho

In <5hj2pdF2a6vn4U1@mid.individual.net>,
"J.O. Aho" <user@example.net> mentions:
>> It's just that I don't want a dozen cheap machines taking up space & using
>> electricity.
>
>I'm not sure on which you save power/electricity on, quite often the new CPUs
>require quite a lot of Ws, I think my laptops CPU draws more than what my
>whole file server does.

Interesting! Hadn't thought of that!

>A quick check with google at Xen-maillist, got that the feature required is
>SVM and with help of google again, I got the following link
>
>http://en.wikipedia.org/wiki/X86_vir...on_.28AMD-V.29
>
>Where it says:
>
>AMD virtualization (AMD-V)
>
>AMD's virtualization extensions to the 64-bit x86 architecture is named AMD
>Virtualization, abbreviated AMD-V. It is still referred to as "Pacifica", the
>AMD internal project code name.
>
>AMD-V is present in all K8 AMD (Athlon 64) processors from stepping "F" and
>all newer processors support AMD-V technology. This applies for all current
>Socket AM2 and Socket F processors.
>
>So AM2 seems to be safe bet.

I read that too, but when I come across a typical processor "model number"
I'm likely to see something like this:

AMD Athlon 64 x2 4200+ Dual Core Socket AM2

or

AMD Athlon 64 X2 3800+ AM2

I can interpret that as, 64-bit, dual core, AM2 socket but I have no idea
how/where I could determine if it has the pacifica extensions, whether or
not it's a K8 and whether or not it has "stepping F".

The wikipedia page said:

"This applies for all current" ...

But.. what does "current" mean?

If I knew how I could interpret: "AMD Athlon 64 x2 4200+ Dual Core Socket AM2"
to tell whether or not it had these extensions, maybe I'd understand.

I see from AMD's site, the number indicates how fast it is, but tells nothing
of whether or not the CPU has these extensions.

>Another reason why not use Sempron is that it has always less cache than the
>X2 and you will want to have large cache, you could go for one X2 with 2x1MB
>cache, but that will more or less double the price for the CPU.

I do appreciate the info, thanks! I don't buy PC's very often.

Jamie
--
http://www.geniegate.com Custom web programming
Perl * Java * UNIX User Management Solutions

Jamie wrote:
> "J.O. Aho" <user@example.net> mentions:

>> AMD virtualization (AMD-V)
>> AMD's virtualization extensions to the 64-bit x86 architecture is named AMD
>> Virtualization, abbreviated AMD-V. It is still referred to as "Pacifica", the
>> AMD internal project code name.
>> AMD-V is present in all K8 AMD (Athlon 64) processors from stepping "F" and
>> all newer processors support AMD-V technology. This applies for all current
>> Socket AM2 and Socket F processors.
>> So AM2 seems to be safe bet.
>
> I read that too, but when I come across a typical processor "model number"
> I'm likely to see something like this:
> AMD Athlon 64 x2 4200+ Dual Core Socket AM2
> or
> AMD Athlon 64 X2 3800+ AM2
> I can interpret that as, 64-bit, dual core, AM2 socket but I have no idea
> how/where I could determine if it has the pacifica extensions, whether or
> not it's a K8 and whether or not it has "stepping F".
> The wikipedia page said:

Yes, AM2 and according the wikipedia, all AM2 has SVM.

> "This applies for all current" ...
> But.. what does "current" mean?

From the date that the entry was written at, you can check that in the page
history, it will take some time.


> If I knew how I could interpret: "AMD Athlon 64 x2 4200+ Dual Core Socket AM2"
> to tell whether or not it had these extensions, maybe I'd understand.

You won't be able to tell that from the name that resellers uses, you need to
see the version number on the CPU and then check the AMD documentation to see
the stepping and features in that CPU. Another possibility is to install the
CPU in a machine and run a CPU check on it (in Linux 'cat /proc/cpuinfo').

If you buy a CPU, you culd always tell the reseller that you want one that
supports SVM, in case it would turn out to miss the feature, then you should
be in most countries be able to return it and get all your money back.


> I see from AMD's site, the number indicates how fast it is, but tells nothing
> of whether or not the CPU has these extensions.

No matter which company's CPU you would buy, you never know exactly what CPU
you get by just the reseller name of the CPU, as that CPU can be stepping 'A',
a few months later the manufacturer has fixed something and then they only
produce stepping 'C' and a few months later they can upgrade it to 'D' and
when they make a major change, then they release the CPU under a new name.

I have two AMD Athlon XP 2500+, both bought a couple of months between, they
sold with the same name, but different stepping.


I hope this do clear up some thoughts for you.
--

//Aho

On Sun, 05 Aug 2007 11:47:52 +0200, J.O. Aho wrote:

> I have two AMD Athlon XP 2500+, both bought a couple of months between, they
> sold with the same name, but different stepping.

Same with the 3500+. My usual vendor stocked both an older and a newer
version when I was ordering parts to build this box.


--


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