Intel Yonah Performance Preview - Part I: The Exclusive First Look at Yonah

Yonah vs. Dothan

We didn’t have much time to put together this piece, but at the same time we wanted to present the most complete picture of Yonah as possible, so we went back to our last Pentium M on the desktop article and configured our Yonah system identically so we’d have as close to an apples-to-apples comparison as possible.  Of course it is impossible to use the same motherboard, due to the socket differences we’ve already mentioned, but the rest of the systems are configured identically.  We apologize in advance for the brevity of the benchmark suite, in due time we will present an even more thorough look at Yonah, but for now we are working with what we’ve got.  Also keep in mind that the platform and processor are both pre-release samples, so performance could change, most likely for the better.

With that said, we've got a question and that is: how does Yonah stack up to Dothan?

Unfortunately, our Yonah only runs at 2.0GHz, and our reference Dothan numbers are from a 2.13GHz CPU - so we don’t get the clock for clock comparison we were hoping for, making it even more difficult for Yonah to impress.  Thankfully our first benchmark is clock speed independent as we look at how cache latencies have changed from Dothan to Yonah using ScienceMark 2.0:

And changed they have indeed.  If you’ll remember from our earlier desktop Pentium M investigations, Dothan’s very quick 10 cycle L2 cache allowed it to be competitive with AMD’s Athlon 64, despite lacking an on-die memory controller.  With the move to Yonah however, the L2 cache latency has gone up a whopping 40%.  While we’re still dealing with a lower access latency than the Pentium 4, this increase will hurt Yonah. 

We’re guessing that the increase in access latency is due to the new dynamically resizable L2 cache that’s used in Yonah.  In order to save power as well as maximize the use of the shared L2 cache between cores, Yonah can dynamically adjust the size of its L2 cache, flushing data to main memory when faced with low demand.  The associated logic is most likely at least partially to blame for the increase in L2 cache latency. 

So Yonah has a slower L2 cache working against it, but two cores and a handful of architectural enhancements working in its favor - let’s see how they stack up in the real world.

First up, we’ve got our business application tests:

Dothan has a sizeable lead in Business Winstone 2004, which we’ve always attributed to its low latency L2 cache.  Since the benchmark gets no benefits from dual core, and doesn’t take advantage of any of the SSE improvements to Yonah, the advantage is clearly in Dothan’s court. 

The SYSMark tests paint a different picture, with Yonah outpacing the faster clocked Dothan by 6 - 17%.  What’s interesting to note is that in these tests, the performance advantage isn’t exclusively attributable to the advantage of having two cores - Yonah’s architectural advancements are at work here as well. 

The digital content creation tests are where Yonah’s improvements should shine:

And shine they do; thanks to a combination of the move to dual core as well as the architectural improvements over Dothan, Yonah shows anywhere between a 16 - 40% increase in performance. 

The DivX test shows what we’ve pretty much seen across the board from dual core scaling in video encoding, so there’s no surprise there.  Our only gaming benchmark, Doom 3, shows a hazier picture with Dothan on top, and Yonah close behind.  We will investigate gaming performance of Yonah much closer later on.  

What we can walk away from these benchmarks with is an idea of the level of improvement to expect from Yonah, but now comes the real test - how does it stack up against other desktop processors, especially the Athlon 64 X2.