The DirectX 12 Performance Preview: AMD, NVIDIA, & Star Swarm
by Ryan Smith on February 6, 2015 2:00 PM EST- Posted in
- GPUs
- AMD
- Microsoft
- NVIDIA
- DirectX 12
Frame Time Consistency & Recordings
Last, but not least, we wanted to also look at frame time consistency across Star Swarm, our two vendors, and the various APIs available to them. Next to CPU efficiency gains, one of the other touted benefits of low-level APIs like DirectX 12 is the ability for developers to better control frame time pacing due to the fact that the API and driver are doing fewer things under the hood and behind an application’s back. Inefficient memory management operations, resource allocation, and shader compiling in particular can result in unexpected and undesirable momentary drops in performance. However, while low-level APIs can improve on this aspect, it doesn’t necessarily mean high-level APIs are bad at it. So it is an important distinction between bad/good and good/better.
On a technical note, these frame times are measured within (and logged by) Star Swarm itself. So these are not “FCAT” results that are measuring the end of the pipeline, nor is that possible right now due to the lack of an overlay option for DirectX 12.
Starting with the GTX 980, we can immediately see why we can’t always write-off high-level APIs. Benchmark non-determinism aside, both DirectX 11 and DirectX 12 produce consistent frame times; one is just much, much faster than the other. Both on paper and subjectively in practice, Star Swarm has little trouble maintaining consistent frame times on the GTX 980. Even if DirectX 11 is slow, it is at least consistent.
The story is much the same for the R9 290X. DirectX 11 and DirectX 12 both produce consistent results, with neither API experiencing frame time swings. Meanwhile Mantle falls into the same category as DirectX 12, producing similarly consistent performance and frame times.
Ultimately it’s clear from these results that if DirectX 12 is going to lead to any major differences in frame time consistency, Star Swarm is not the best showcase for it. With DirectX 11 already producing consistent results, DirectX 12 has little to improve on.
Finally, along with our frame time consistency graphs, we have also recorded videos of shorter run-throughs on both the GeForce GTX 980 and Radeon R9 290X. With YouTube now supporting 60fps, these videos are frame-accurate representations of what we see when we run the Star Swarm benchmark, showing first-hand the overall frame time consistency among all configurations, and of course the massive difference in performance.
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Alexey291 - Friday, February 6, 2015 - link
It can be as free as it likes. In fact for all I care they can pay me to install it... Still not going to bother. And you know why? There's no benefit for me who only uses a Windows desktop as a gaming machine.Not a single one. Dx12 is not interesting either because my current build is actually limited by vsync. Nothing else but 60fps vsync (fake fps are for kids). And it's only a mid range build.
So why should I bother if all I do in Windows at home is launch steam (or a game from an icon on the desktop) aaaand that's it?
Nuno Simões - Friday, February 6, 2015 - link
Clearly, you need to read the article again.Alexey291 - Saturday, February 7, 2015 - link
There's a difference in a benchmark. Well surprise surprise. On the other hand games are likely to be optimised before release. Even games by Ubisoft MIGHT be optimised somewhat.So the difference between dx11 and 12 will be imperceptible as usual. Just like the difference between ten and eleven was even though benchmarks have always shown that 11 is more efficient and generally faster.
Nuno Simões - Saturday, February 7, 2015 - link
So, it's faster and more efficient, but that's worthless?What happened between 10 and 11 is that developers used those improevments to add to substance, not speed, and that is probably going to happen again. But anyway you see it, there is a gain in something. And, besides, just the gains from frametimes and lower buffers is worth it. Less stutter is always a good thing.
And the bad optimisation from some developers is hardly DX's fault, or any other API for that matter. Having a better API doesn't suddenly turn all other API's into s*it.
inighthawki - Saturday, February 7, 2015 - link
What are you blabbering on about? No benefit? Fake fps? Do you even know anything about PCs or gaming?Alexey291 - Saturday, February 7, 2015 - link
You don't actually understand that screen tearing is a bad thing do you? :)Murloc - Saturday, February 7, 2015 - link
I've never seen screen tearing in my life and I don't use vsync despite having a 60 Hz monitor.Fact is, you and I have not much to gain from DX12, apart for the new features (e.g. I have a dx10 card and I can't play games with the dx11 settings which do add substance to games, so it does have a benefit, you can't say there is no difference).
So whether you upgrade or not will not influence the choices of game engine developers.
The CPU bottlenecked people are using 144Hz monitors and willing to spend money to get the best so they do gain something. Not everybody is you.
Besides, I will be upgrading to windows 10 because the new features without the horrible w8 stuff are really an improvement, e.g. the decent copy/paste dialog that is already in w8.
Add the fact that it's free for w8/8.1 owners and it will see immediate adoption.
Some people stayed on XP for years instead of going to Vista before 7, but they eventually upgraded anyway because the difference in usability is quite significant. Not being adopted as fast as you some guy on the internet think would be fast enough is no excuse to stop development, otherwise someone else will catch up.
inighthawki - Saturday, February 7, 2015 - link
I well understand what screen tearing is, but not locking to vsync doesn't suddenly make it 'fake FPS.' You literally just made up a term that means nothing/. You're also ignoring the common downside of vsync: input lag. For many people it is extremely noticeable and makes games unplayable unless they invest in low latency displays with fast refresh rates.Margalus - Saturday, February 7, 2015 - link
it does make it "fake fps" in a way. It doesn't matter if fraps is telling you that you are getting 150fps, your monitor is only capable of showing 60fps. So that 150fps is a fallacy, you are only seeing 60fps. And without vsync enabled, those 60fps that your monitor is showing are comprised of pieces more than one frame in each, hence the tearing.but other than that, I can disagree with most everything that poster said..
inighthawki - Saturday, February 7, 2015 - link
Correct, I realize that. But it's still not really fake. Just because you cannot see every frame it renders does not mean that it doesn't render them, or that there isn't an advantage to doing so. By enabling vsync, you are imposing a presentation limit on the application. It must wait until the vsync to present the frame, which means the application must block until it does. The faster the GPU is at rendering frames, the larger impact this has on input latency. By default, DirectX allows you to queue three frames ahead. this means if your GPU can render all three frames within one refresh period of your monitor, you will have a 3 frame latency (plus display latency) between when it's rendered and when you see it on screen, since each frame needs to be displayed in the order it is rendered. With vsync off, you get tearing because there is no wait on presents. The moment you finish is the moment you can swap the backbuffer and begin the next frame. You always have (nearly) the minimal amount of latency possible. This is avoidable with proper implementations of triple buffering that allow the developer to discard old frames. In all cases, the fps still means something. Rendering at 120fps and only seeing 60 of them doesn't make it useless to do so.