[ale] Virtualization

[Benjie]

JK, how old is your box?  Newer Intel and AMD multi-core CPU's have
extensions that provide better performance specifically for
virtualization ( VTx and AMD-V.)  You can enable these extensions
through the settings in VirtualBox. ( Although you will probably be
forced to re-install the XP guest if you do.)  Your guest VM's are
operating in para-virtualization mode which is going to provide less
performance than full virtualization.  (  grep for vmx in
/proc/cpuinfo, that will show wether or not your cpu supports full
virtualization.  You should also check your BIOS to see if you need to
turn on virtualization features if they are there.)  VirtualBox is
great for desktop use; VMWare Workstation only edges it when you are
running multiple VM's.  And its hard to beat free ( it definately
outperforms VMWare Player.)  I wouldn't go with VMWare Server or Xen
for desktop use.  As for VMWare Server, I would look into ditching it
for VMWare ESXi.  It provides much improved performance and
granularity in tuning VM's over the old Server product.  It is free,
as in gratis.  You just need to register with VMWare's site and get a
key.  It will time out after 60 days if you don't.

On Tue, Feb 24, 2009 at 9:50 PM, Christopher Fowler
<cfowler at outpostsentinel.com> wrote:
> JK wrote:
>> So I'm running VirtualBox on a 3Ghz dual-proc P4 with 3GB of
>> RAM.  (Maybe it's just hyperthreading, but /proc/cpuinfo
>> reports two CPUs, and I haven't looked inside the box. Got
>> the machine from my employer after a cancelled project.) The
>> host OS is Ubuntu Intrepid, and the guests are mostly WinXP.
>>
>> Whenever a guest machine does the tiniest little thing --
>> scroll a command window a couple of lines, for example --
>> it seems to peg the guest's (virtual) CPU, and really
>> elevate the CPU usage on the host.  This seems unnecessary,
>> and I'm wondering if VMWare or Xen or some other virtualization
>> technology makes better use of the underlying hardware.
>>
>> Any experiences to share?
>>
>>
> This is my experience as well.  I think many companies look at
> virtualization as a way to save
> money on hardware.  Yes it does but the guest must be suited for it.
>
> I run about 5 guests on a CentOS 5.2 host with Server 2.0.  We have one
> Windows 2003 Server guest
> and the rest are CentOS 5.2.
>
> Sometimes when I edit a file on a guest with vim it may take a second
> for vim to load it or for it to write
> it.  It is almost as if the guest is blocking in I/O to the disk.  When
> typing over SSH I can sometimes
> feel a latency on the guest I do not feel on real servers.
>
> For the most part the average load on each guest is probably less than
> 0.25.  This works well.  rarely
> we get a runaway process on one of the guests.  When this happens, each
> guest takes a major performance
> hit.  They all share the same 2 CPUs on the host.  I wish there was a
> way in server to limit a guest to
> a certain percentage of the host's CPU.
>
>
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