What's changed in Catalyst 13.2 beta—and what hasn't
AMD appears to be making good on its promise to address frame latency issues via driver updates. Andrew Dodd, AMD's Catalyst guru, tells us a variant of the Catalyst 13.2 beta driver we tested will be released via AMD's website next week. That should be a nice first step toward shoring up Radeon performance compared to the competition
We asked Mr. Dodd whether the changes included in this beta driver would impact performance generally in DirectX 9 applications or only in the three DX9-based games we tested. We also inquired about whether the previously mentioned buffer size tweak for Borderlands 2 was included. Here's his answer:
Basically the fix was different per application (for the DX9 applications) – each fix involved tweaking various driver parameters. In the case of Borderlands 2, yes it did involve tweaking the buffer size.
So what we have in Cat 13.2 is a series of targeted tweaks that appear to work quite well for the games in question. However, Dodd says additional improvements are coming down the pike, including a rewrite of the software memory manager for GPUs based on the Graphics Core Next architecture that should bring a more general improvement:
The driver does not yet contain the new video memory manager. Our intention is release a new driver in a few weeks, which does include the new Video memory manager, which will help resolve latency issues for DX11/DX10 applications.
We look forward to the updates and to the improved gaming experience that Radeon users should be able to enjoy as a result.
Frame latencies: a new frontier
One of the tougher questions we had for AMD, in the wake of our discovery of these latency issues and their subsequent move to fix them, was simply this: how can we know that we won't see similar problems in the future? Dodd addressed this question directly in our correspondence, noting that AMD will be changing its testing procedures in the future in order to catch frame latency problems and prevent them:
Up until this point we had mostly assumed that there were occasional flickers in frame rate, but we had thought these were related to the fact that modern games mostly have streaming architectures and limitations of scheduling in the OS. We definitely will start regular measurements to ensure we track improvements, and stop regressions. Long term, we want to work with game developers and Microsoft to ensure these kinds of latency issues don't keep cropping up.
That's exactly the sort of answer we want to hear, and we'll be watching and testing future Radeon drivers and GPUs in order to see how well AMD executes on that plan.
That answer also blows up one of the assumptions that we've held since we published our first Inside the second article. We'd assumed that, although we were among the first to conduct a frame-by-frame analysis of game performance in public, such analyses had been happening behind the scenes at the big GPU makers as a matter of course for a long time. Our interactions with AMD, Nvidia, and others in the industry have since changed our view.
In fact, at CES last week, I was discussing the latest developments with Nvidia's Tom Petersen, and he told me there was one question I failed to ask in my investigation of Radeon-versus-GeForce frame latencies: why did Nvidia do so well? Turns out, he said, Nvidia has started engineering its drivers with an eye toward smooth and consistent frame rendering and delivery. I believe that effort began at some point during the Fermi generation of GPUs, so roughly two years ago, max. Clearly, that focus paid dividends in our comparison last month of the GTX 660 Ti and the Radeon HD 7950.
From what I've gathered, in the past, developers have used nifty tools like the one we used to dissect Crysis 2 tessellation weirdness. These tools can show you the time required by each stage of the process of rendering a frame. Reducing those time slices has often been the focus of optimization efforts. Meanwhile, the performance labs at GPU makers and elsewhere have largely focused on FPS-based benchmarks to provide a sense of overall comparative performance. It seems efforts to bridge the gap between these two domains, to look at the overall frame latency picture and to ensure consistency there, have only recently ramped up.
Of course, AMD's participation is crucial to the success of such efforts. We look forward to seeing what sort of benefits the next round of Catalyst driver updates can provide—and to an ongoing conversation about how best to handle the complex collection of issues this new focus has unearthed.You can measure my response times on Twitter.