AMD Tweaking Radeon Drivers To Reduce Frame Latency Spikes

crookedvulture writes "Slashdot has previously covered The Tech Report's exposure of frame latency issues with recent AMD graphics processors. Both desktop and notebook Radeons exhibit frame latency spikes that interrupt the smoothness of in-game animation but don't show up in the FPS averages typically used to benchmark performance. AMD has been looking into the problem and may have discovered the culprit. The Graphics Core Next architecture underpinning recent Radeons is quite different from previous designs, and AMD has been rewriting the memory management portion of its driver to properly take advantage. This new code improves frame latencies, according to AMD's David Baumann, and the firm has accelerated the process of rolling it into the official Catalyst drivers available to end users. Radeon owners can take some comfort in the fact that a driver update may soon alleviate the frame latency problems associated with AMD's latest GPUs. However, they might also be disappointed that it's taken AMD this long to optimize its drivers for the now year-old GCN architecture."

Comments

Give them credit

[Anonymous Coward]

taken AMD this long to optimize its drivers for the now year-old GCN architecture.

Give them some credit... they've acknowledged the problem and this isn't a simple tweaking/bugfix, this is a complete redesign and rewrite of the entire driver architecture.

Re:Give them credit

[hattig]

Well, it's in the memory manager portion of the driver. Memory management isn't easy at the best of times, and when you're dealing with a GPU that has thousands of cores, and each of those cores has its own local memory, and shared memory with a local cluster group, and then there are software controllable caches further up the hierarchy, I can see how writing this code could be fraught with difficulty.

And as many of us here have worked in professional software environments, I'm sure we can all see how something that was pretty hard to pin down like these latency spikes might not have been a top priority for development, even if they were aware of it at all - after all the FPS figures were great. You'd end up with a driver kernel that had some magic that nobody would want to touch, and most of the work would be game specific optimisations and higher level optimisations. A year sounds about right really.

Re:Give them credit

[Anonymous Coward]

More than that, this frame latency issue is new to the recent drivers - possibly even restricted to the 12.11 beta drivers, which one might expect to have the occasional issue. Further, other review sites that investigate the smoothness of gameplay, even if not by quite the same method (ex: Hard|OCP), have not found the issues that Tech Report has, which leads me to suspect that it might not be a universal issue.

I think that Tech Report has been very irresponsible in their handling of this issue. They've been quick to condemn, ignoring that the driver is _not_ a final version, and apparently unwilling to investigate the disparity between their older results with the same cards/older drivers (which had no such frame latency issues) and their new results. Frankly, I'm not willing to give them any regard as a review site any longer - their frame latency methodology certainly has merit, but they seem to be utterly incompetent in actually analyzing or investigating the results.

Re:Give them credit

[nanoflower]

Only one problem with what you suggest is that it is based on bad information. TR made the effort to look at different versions of the drivers and they've tested it on Win7 and Win8. Also only a couple of other sites have done the same level of testing frame rates that TR has been doing and they've found the same issues. Then you add in that AMD has looked into the issue and acknowledged there is a real issue that they need to address. So you are doing a disservice to Tech Report by misstating the situation and ignoring the other sites that have agreed with their findings.

Technology sites give brainddead measurements

[PhrostyMcByte]

This only went on so long because tech sites use such poor, useless benchmarking methods. Minimum/Average/Maximum FPS, or often just Average/Maximum FPS, are worthless!

A game, or a video card, can average 100fps, but still have that one frame every second that performs some extra I/O and takes 3x longer than usual causing an annoying stutter effect.

A good first step would be to use frame latency percentiles.. i.e. 90% of frames are at least 60 FPS, 95% of frames are at least 50 FPS, 99% of frames are at least 40 FPS.

The next step is to measure spikes themselves -- low framerate sucks, but not nearly as much as a stuttering framerate. A sudden spike from constant 10ms/frame to 50ms/frame and back should be counted as far more detrimental than a smooth transition from constant 10ms to constant 25ms.

Re:Technology sites give brainddead measurements

[hattig]

You should be reading the Tech Report GPU reviews then, they have all that stuff included.

Re:Technology sites give brainddead measurements

[TubeSteak]

This only went on so long because tech sites use such poor, useless benchmarking methods. Minimum/Average/Maximum FPS, or often just Average/Maximum FPS, are worthless!

Umm... Tech Report has been doing frame latency benchmarking for over a year now.
And I'm not sure if they were the first ones to come up with the idea, but I know they're not the only reviewers using that benchmark.

Re:I read: AMD updates video driver

[LordLimecat]

AMD didnt have a class action lawsuit requiring them to purchase new laptops for end users involved in the claim.