How does ARM Cortex A8 compare with a modern x86 processor

Question

I was wondering how does a modern ARM chip based on ARM Cortex A8 compare, in clock-for-clock performance and capability, to a modern x86 chip such as a Core 2 Duo or Core i5?

I realise due to the different instruction sets it'll depend heavily on what you're doing.

To put it another way, rendering a web page in webkit on a 1GHz ARM Cortex A8 based chip should be about equivalent to doing in on a Core i5 at ______ MHz?

Update October 2013:

Since I asked this question years ago it's become a lot more common, when reading about mobile devices, to see architecture-agnostic benchmarks that you can compare across platforms - for example, in-browser benchmarks like Sunspider in Webkit will run on just about anything and you see these in reviews all the time now. And there's things like Geekbench now.

Answer 1

There are some benchmarks that compute scores that can be used for such comparisons. Try searching for DMIPS/MHz and maybe also CoreMark/MHz.

I'd expect them to be more comparable in performance to Atom CPUs though.

Answer 2

What you're looking for is quite hard to find, mostly because you're comparing apples to oranges. You can't really compare load times for a webpage, or any other thing for that matter, mostly because these operations are not only CPU dependent, they're also dependent on the OS they're running and on the hardware that it uses (RAM being a major candidate).

Also, ARM chips are highly optimized for just a few specific tasks, while on a Core i7, for instance, you also have CPU operations used for complex stuff (AES encryption, video encoding, parallel processing) that an ARM CPU simply doesn't need to do.