A start to proper testing
During all the commotion last week surrounding the release of a new Ashes of the Singularity DX12 benchmark, Microsoft's launching of the Gears of War Ultimate Edition on the Windows Store and the company's supposed desire to merge Xbox and PC gaming, a constant source of insight for me was one Andrew Lauritzen. Andrew is a graphics guru at Intel and has extensive knowledge of DirectX, rendering, engines, etc. and has always been willing to teach and educate me on areas that crop up. The entire DirectX 12 and Unified Windows Platform was definitely one such instance.
Yesterday morning Andrew pointed me to a GitHub release for a tool called PresentMon, a small sample of code written by a colleague of Andrew's that might be the beginnings of being able to properly monitor performance of DX12 games and even UWP games.
The idea is simple and it's implementation even more simple: PresentMon monitors the Windows event tracing stack for present commands and records data about them to a CSV file. Anyone familiar with the kind of ETW data you can gather will appreciate that PresentMon culls out nearly all of the headache of data gathering by simplifying the results into application name/ID, Present call deltas and a bit more.
Gears of War Ultimate Edition - the debated UWP version
The "Present" method in Windows is what produces a frame and shows it to the user. PresentMon looks at the Windows events running through the system, takes note of when those present commands are received by the OS for any given application, and records the time between them. Because this tool runs at the OS level, it can capture Present data from all kinds of APIs including DX12, DX11, OpenGL, Vulkan and more. It does have limitations though - it is read only so producing an overlay on the game/application being tested isn't possible today. (Or maybe ever in the case of UWP games.)
What PresentMon offers us at this stage is an early look at a Fraps-like performance monitoring tool. In the same way that Fraps was looking for Present commands from Windows and recording them, PresentMon does the same thing, at a very similar point in the rendering pipeline as well. What is important and unique about PresentMon is that it is API independent and useful for all types of games and programs.
PresentMon at work
The first and obvious question for our readers is how this performance monitoring tool compares with Frame Rating, our FCAT-based capture benchmarking platform we have used on GPUs and CPUs for years now. To be honest, it's not the same and should not be considered an analog to it. Frame Rating and capture-based testing looks for smoothness, dropped frames and performance at the display, while Fraps and PresentMon look at performance closer to the OS level, before the graphics driver really gets the final say in things. I am still targeting for universal DX12 Frame Rating testing with exclusive full screen capable applications and expect that to be ready sooner rather than later. However, what PresentMon does give us is at least an early universal look at DX12 performance including games that are locked behind the Windows Store rules.
BF4 Integrates FCAT Overlay Support
Back in September AMD publicly announced Mantle, a new lower level API meant to offer more performance for gamers and more control for developers fed up with the restrictions of DirectX. Without diving too much into the politics of the release, the fact that Battlefield 4 developer DICE was integrating Mantle into the Frostbite engine for Battlefield was a huge proof point for the technology. Even though the release was a bit later than AMD had promised us, coming at the end of January 2014, one of the biggest PC games on the market today had integrated a proprietary AMD API.
When I did my first performance preview of BF4 with Mantle on February 1st, the results were mixed but we had other issues to deal with. First and foremost, our primary graphics testing methodology, called Frame Rating, wasn't able to be integrated due to the change of API. Instead we were forced to use an in-game frame rate counter built by DICE which worked fine, but didn't give us the fine grain data we really wanted to put the platform to the test. It worked, but we wanted more. Today we are happy to announce we have full support for our Frame Rating and FCAT testing with BF4 running under Mantle.
A History of Frame Rating
In late 2012 and throughout 2013, testing graphics cards became a much more complicated beast. Terms like frame pacing, stutter, jitter and runts were not in the vocabulary of most enthusiasts but became an important part of the story just about one year ago. Though complicated to fully explain, the basics are pretty simple.
Rather than using software on the machine being tested to measure performance, our Frame Rating system uses a combination of local software and external capture hardware. On the local system with the hardware being evaluated we run a small piece of software called an overlay that draws small colored bars on the left hand side of the game screen that change successively with each frame rendered by the game. Using a secondary system, we capture the output from the graphics card directly, intercepting it from the display output, in real-time in an uncompressed form. With that video file captured, we then analyze it frame by frame, measuring the length of each of those colored bars, how long they are on the screen, how consistently they are displayed. This allows us to find the average frame rate but also to find how smoothly the frames are presented, if there are dropped frames and if there are jitter or stutter issues.
Subject: Graphics Cards | June 20, 2013 - 08:05 PM | Ryan Shrout
Tagged: radeon, nvidia, geforce, frame rating, fcat, crossfire, amd
Well, the date has been set. AMD publicly stated on its @AMDRadeon Twitter account that a new version the prototype driver we originally previewed with the release of the Radeon HD 7990 in April will be released to the public on July 31st. For a problem that many in the industry didn't think existed.
Big news for CrossFire! We plan to release our driver that delivers improved multi-GPU frame pacing on July 31. More info soon.
— AMD Radeon Graphics (@AMDRadeon) June 20, 2013
Since that April release AMD has been very quiet about its driver changes and actually has refused to send me updated prototypes over the spring. Either they have it figured out or they are worried they haven't - but it looks like we'll find out at the end of next month and I feel pretty confident that the team will be able to address the issues we brought to light.
For those of you that might have missed the discussion, our series of Frame Rating stories will tell you all about the issues with frame pacing and stutter in regards to AMD's CrossFire multi-GPU technology.
- Frame Rating Dissected: Full Details on Capture-based Graphics Performance Testing
- Frame Rating: Visual Effects of Vsync on Gaming Animation
- Frame Rating: AMD Improves CrossFire with Prototype Driver
AMD gave the media a prototype driver in April to test with the Radeon HD 7990, a card that depends on CrossFire to work correctly, and the improvements were pretty drastic.
So what can we expect on July 31st? A driver that will give users the option to disable or enable the frame pacing technology they are developing - though I am still of the mindset that disabling is never advantageous. More to come in the next 30 days!
Subject: Editorial, Graphics Cards | May 9, 2013 - 03:37 AM | Ryan Shrout
Tagged: video, nvidia, live, frame rating, fcat
Update: Did you miss the live stream? Watch the on-demand replay below and learn all about the Frame Rating system, FCAT, input latency and more!!
I know, based solely on the amount of traffic and forum discussion, that our readers have really adopted and accepted our Frame Rating graphics testing methodology. Based on direct capture of GPU output via an external system and a high end capture card, our new systems have helped users see GPU performance a in more "real-world" light that previous benchmarks would not allow.
I also know that there are lots of questions about the process, the technology and the results we have shown. In order to try and address these questions and to facilitate new ideas from the community, we are hosting a PC Perspective Live Stream on Thursday afternoon.
Joining me will be NVIDIA's Tom Petersen, a favorite of the community, to talk about NVIDIA's stance on FCAT and Frame Rating, as well as just talk about the science of animation and input.
The primary part of this live stream will be about education - not about bashing one particular product line or talking up another. And part of that education is your ability to interact with us live, ask questions and give feedback. During the stream we'll be monitoring the chat room embedded on http://pcper.com/live and I'll be watching my Twitter feed for questions from the audience. The easiest way to get your question addressed though will be to leave a comment or inquiry here in this post below. It doesn't require registration and this will allow us to think about the questions before hand, giving it a better chance of being answered during the stream.
Frame Rating and FCAT Live Stream
11am PT / 2pm ET - May 9th
So, stop by at 2pm ET on Thursday, May 9th to discuss the future of graphics performance and benchmarking!