The commentary around Bulldozer, AMD’s latest processor line, is that it’s disappointing, a catastrophe, absolutely positively awful and so on, for miles and miles. And it’s a shame for AMD that Ars, Extreme Tech and the usual suspects have no imagination beyond their benchmarks when it comes to judging processors.
The numbers don’t lie of course – the benchmarks show that Bulldozer’s best is slower than Intel’s, by a long way, and most of those benchmarks care about absolute amount of data processed, numbers crunched and so on. Ars Technica concludes:
AMD compromised single-threaded performance in order to allow Bulldozer to run more threads concurrently, and that trade-off simply hasn’t been worth it.
But everyone’s performance tests make an assumption: that the processor is working for one person at a time, and that person wants it to crunch through as many numbers as possible for their benefit. Those numbers might be rendering frames of Battlefield 3, editing a huge photo or ripping a CD. Benchmarks sum it up the same way – however many ways a single job can be split to use a processor’s cores, they’re only interested in who gets to the finish line fastest.
And Intel still wins, I get it. Even AMD admit in a recent interview that their older processors still perform better for a lot of people:
We understand our customers make purchase decisions based on how they use their PCs, and in many cases our AMD Phenom™ II processors are a great (purchase).
They are struggling to pitch themselves against Intel to the gamers, power-hungry desktop PC users and the benchmark sites. They know they can’t get the same excitable press any more, not for years and another generation of processor. That’s probably why they’re temporarily giving up this fight on pure brawn, laying off hundreds in their PR and marketing departments a couple of weeks ago.
But instead of doing one thing for one person, let’s instead assume that a processor is under siege from 300 warring factions, all wanting to run separate and unpredictable work loads. The benchmark that interests us is: assuming we are running 299 “hostile” jobs, how quickly does that 300th job complete? If we vary those 299 jobs in nature, how reliable is the performance of that 300th? The time of that one lonely, slow, job is what I’m interested in.
For BigV where we are running a massively “multi-tenant” system, we really are planning to put in the order of 300 different customers on a single server. It’s far more important to have a reliable average performance for a virtual machine than the absolute fastest possible performance. I’ve not (yet) seen any benchmarks that test in this way, but it seems to us that more separate hardware cores must achieve this goal better than a single software-switched core.
If that weren’t the case I find it hard to understand investment in massively parallel server systems like the 768-core Atom server or super low-power 480-core ARM systems. Big multi-tenant systems don’t need to be the fastest, they just need to perform consistently.
For BigV, we just want more cores. The speed is almost irrelevant. While AMD’s performance is within the same ball park as Intel’s, they’ll work out very nicely for us virtual machine-mongers. And the low price of Bulldozer chips is just icing – a 32-core, 128GB system is extremely affordable and helps us keep our pricing to customers low.
AMD are gearing up for a different fight, and they don’t need press from the benchmark sites to prove them the winners. So while my gaming PC will stick with a Phenom for a while yet, BigV is going to be using an awful lot of Bulldozer chips in the near future.