AMD addressing microstuttering for single-GPU and Crossfire.

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Avatar image for Marfoo
#1 Posted by Marfoo (5997 posts) -

The issue of frame-latency problems with single-GPU setups (particularly Radeon) recently has sparked a lot talk on our forums, and for even longer, the issues of microstuttering with Crossfire and SLI setups has long been an issue that has not been addressed. In a very lenghthy discussion (worth the read if you're interested in the interworkings of everything, as I am) Anandtech spoke with AMD about why the problem is there, how it can be resolved and some nifty features they will be adding to their drivers later this year.

The full read is here: http://www.anandtech.com/show/6857/amd-stuttering-issues-driver-roadmap-fraps

Here is a recap for those who don't want to read.

1. Radeon has latency issues.

  • This is true, and AMD now evaluated frame latency for every game they optimize.
    • As a result of stuttering optimzations, AMD has squeezed untapped potential from their GPUs. (ex. 13% in Borderlands!)
    • Expect better consistency and performance from all games from here on out.
  • FRAPS is can sometimes provide false positives of stuttering because it measures the wrong part of the pipeline
    • FRAPS measures time between "present()" calls, which is not a good indicator of when the frame actually reaches your screen.
    • FRAPS may indicate latency spikes even when frames are hitting your screen in a consistent manner.
    • More in depth tools, like GPUView are needed to truly asses frame latency.

2. Crossifire Microstuttering.

  • The primary method for Crossfire/SLI is AFR (alternate frame rendering).
    • GPUs render every other frame.
    • Best results happen when GPU2 starts rending the next frame when GPU1 is halfway done with the present frame.
  • Timing issues occur.
    • Sometimes one frame takes longer to render than other making timing hard to predict.
    • Sometimes the next frame depends on information from the previous frame
    • These timing issues cause "microstuttering".
  • Microstuttering can be smoothed out by holding onto frames longer.
    • Proividng a buffer time allows more consistent frame latencies.
    • Providing a buffer time will result in "input lag".
    • The effect is similar to enabling vsync.
  • Giving the user control.
    • Crossfire users will be able to select two modes of operation.
    • Mode 1: Traditional mode, frame latencies are reduced, no input lag. Microstuttering occurs.
    • Mode 2: Smooth mode, a buffer is utilized to smooth out microstuttering, input lag occurs.

The Bottom Line

  • AMD admits to finding latency issues.
  • All titles are already being screened for latency issues and optimized. (all games from here on out should be as stutter free as possible)
  • Optimizations have increased performance on AMD GPUs.
  • Micostuttering will be addressed for Crossfire setups.
  • Crossfire users will gain new driver options to control microstuttering in July.


Avatar image for Marfoo
#2 Posted by Marfoo (5997 posts) -
Lol, guess I was the only one who found this interesting.
Avatar image for Cyberdot
#3 Posted by Cyberdot (3928 posts) -

Damn, this is why I'm avoiding AMD. I've been hearing a lot of negative feedback from the AMD userbase.

Avatar image for Marfoo
#4 Posted by Marfoo (5997 posts) -

Damn, this is why I'm avoiding AMD. I've been hearing a lot of negative feedback from the AMD userbase.

Cyberdot
Well, I can tell you they've really fixed the single-GPU stuttering stuff. The only real game I saw it in was Skyrim (and the whole time I thought it was just the engine loading objects as you explored) but now it's smooth as butter. I'm just glad they're honest about it and present the problem at a technical level and are offering solutions. As for Crossfire/SLI, ATI users and Nvidia alike have been complaining about microstutter for years. This is the first time either company has offered an explanation of why it happens and is going to provide tools to deal with it, pretty cool in my book.
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#5 Posted by soolkiki (1783 posts) -

Hmm...I wondered...Usually I got stuttering when I was running and looking down at the same time and at no other time. I'll have to see if all my drivers are up to date.

Avatar image for Marfoo
#6 Posted by Marfoo (5997 posts) -

Hmm...I wondered...Usually I got stuttering when I was running and looking down at the same time and at no other time. I'll have to see if all my drivers are up to date.

soolkiki
Interesting, I'll have to try that, see if it affect me too.
Avatar image for Krigen89
#7 Posted by Krigen89 (3907 posts) -
Lol, guess I was the only one who found this interesting.Marfoo
I think it's super interesting, but really had nothing to add lol.
Avatar image for Marfoo
#8 Posted by Marfoo (5997 posts) -
[QUOTE="Marfoo"]Lol, guess I was the only one who found this interesting.Krigen89
I think it's super interesting, but really had nothing to add lol.

Okay, good to know, lol.
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#9 Posted by Angry_Mushroom (708 posts) -
Can't say I've had much of an issue with stuttering in BF3 since most of my problems stem from lag. Still it is nice to see AMD acknowledge this issue, and work to fix it. Since I have a pair of 5850s running in my rig I'm looking forward to playing with the settings.
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#10 Posted by andmcq (256 posts) -

Beautiful. They need to fix this otherwise there's little reason to go AMD and no reason to go Crossfire (frame latency is much lower on SLi).

Avatar image for Elann2008
#11 Posted by Elann2008 (33028 posts) -
It's about damn time.
Avatar image for mitu123
#12 Posted by mitu123 (155088 posts) -

This makes me interested in trying Crossfire whenever I go back to AMD again.

Avatar image for osan0
#13 Posted by osan0 (14851 posts) -
Note to self: update drivers in a few months. in fairness though i havent really noticed it on my rig....though maybe i have but am blaming the engine loading in assets as mentioned above. my laptop uses an AMD a6 3420 though and i currently dont have access to my PC. although it plays skyrim pretty well it does stutter at times and, i suspect, that is not a microstuttering problem. funny story though....my laptop plays skyrim better than oblivion.
Avatar image for Marfoo
#14 Posted by Marfoo (5997 posts) -
[QUOTE="osan0"]Note to self: update drivers in a few months. in fairness though i havent really noticed it on my rig....though maybe i have but am blaming the engine loading in assets as mentioned above. my laptop uses an AMD a6 3420 though and i currently dont have access to my PC. although it plays skyrim pretty well it does stutter at times and, i suspect, that is not a microstuttering problem. funny story though....my laptop plays skyrim better than oblivion.

Oblivion does not make good use of multi-core, Skyrim is easier to run as a result.
Avatar image for blaznwiipspman1
#15 Posted by blaznwiipspman1 (6610 posts) -

i didnt notice any microstuttering so i could care less about this however the performance increase is welcome.

Avatar image for godzillavskong
#16 Posted by godzillavskong (7904 posts) -
[QUOTE="Cyberdot"]

Damn, this is why I'm avoiding AMD. I've been hearing a lot of negative feedback from the AMD userbase.

Marfoo
Well, I can tell you they've really fixed the single-GPU stuttering stuff. The only real game I saw it in was Skyrim (and the whole time I thought it was just the engine loading objects as you explored) but now it's smooth as butter. I'm just glad they're honest about it and present the problem at a technical level and are offering solutions. As for Crossfire/SLI, ATI users and Nvidia alike have been complaining about microstutter for years. This is the first time either company has offered an explanation of why it happens and is going to provide tools to deal with it, pretty cool in my book.

I'm glad they're addressing it. Hasn't really been that bad with my 6870s. VRAM limitations is my issue and no driver update is gonna fix that. Lol
Avatar image for Elann2008
#17 Posted by Elann2008 (33028 posts) -

This makes me interested in trying Crossfire whenever I go back to AMD again.

mitu123
Same. This is really good on them (AMD). This was something I was hoping they would address since the HD 4870 days. Reading this: "As a result of stuttering optimzations, AMD has squeezed untapped potential from their GPUs. (ex. 13% in Borderlands!) Expect better consistency and performance from all games from here on out." Makes me really happy.
Avatar image for Marfoo
#18 Posted by Marfoo (5997 posts) -
[QUOTE="mitu123"]

This makes me interested in trying Crossfire whenever I go back to AMD again.

Elann2008
Same. This is really good on them (AMD). This was something I was hoping they would address since the HD 4870 days. Reading this: "As a result of stuttering optimzations, AMD has squeezed untapped potential from their GPUs. (ex. 13% in Borderlands!) Expect better consistency and performance from all games from here on out." Makes me really happy.

Yeah, it would be very interesting to see how much more they could have gotten out of R700. My 4870 Crossfire setup ran like a champ though, I ran it from summer 2008 until just this January.
Avatar image for kraken2109
#19 Posted by kraken2109 (13271 posts) -

i didnt notice any microstuttering so i could care less about this however the performance increase is welcome.

blaznwiipspman1
The expression is 'couldn't care less'