[Malvern] Intel Atom Processors

[Andrew Oakley]

Ian Pascoe wrote:
> Can anyone tell me what the difference is between an Intel 
> Atom 270 and 530 (think they're the right numbers) CPUs?

http://ark.intel.com/ProductCollection.aspx?familyID=29035

Two main features: 530 has VT-x and demand-based switching with enhanced
halt state, 270 has none of those.

Demand-based switching and enhanced halt state are both to do with
saving power. Demand-based switching means the chip can underclock
itself when there is a low load. Enhanced halt state basically switches
off some parts of the CPU when there is a low load. Neither of these are
noticable to the end user; as far as the end user is concerned, the
machine carries on working; it just lasts longer on the battery.

So a 530-based netbook may last longer on a single charge than a 270 on
the same battery.

VT-x is on-chip virtualisation support. Basically the 530 can run
virtual machines faster, particularly for grunt work such as
compilation, video transcoding and kernel process handling.

http://www.vmware.com/pdf/Perf_ESX_Intel-EPT-eval.pdf

My own experience was, I felt that video encoding on a virtual machine
on my desktop Intel Celeron E3300 (VT-x, 2.5GHZ, no overclock,
dual-core, 1MB L2 cache, 40 quid) was noticably faster than on a virtual
machine on my Intel Core 2 Duo E7200 (no VT-x, 2.5GHz overclocked to
3.5GHz, dual-core, 3MB L2 cache, 90 quid). I don't have exact benchmarks
for that; I've been meaning to make some for several weeks, especially
given that the Celeron E3300 is essentially the bargain multi-core chip
of the decade.

Not all applications benefit. Databases seem to have no gain. Some
people have reported that graphic display applications (eg. 3D games,
video output) actually run slightly slower with VT-x. It can also depend
heavily on how well your virtualisation host software is built to use
VT-x.
http://tombuntu.com/index.php/2007/10/01/should-you-enable-intels-vt-x-i
n-virtualbox/

If you are not intending to run virtual machines, it matters not one
jot. Intel have started adding VT-x to most of their new chips, since
Windows 7 relies on virtualisation to support many legacy Windows XP
applications.

Andrew Oakley
Head of Software Development
Higher Education Statistics Agency (HESA)
95 Promenade, Cheltenham, Gloucestershire GL50 1HZ
T 01242 211460  F 01242 211122  W www.hesa.ac.uk


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