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PatimPatam
Up and Coming
December 13, 2014

UE4 performance issues since the Oculus 0.4.3 runtime

Hello there,

Please try to have a look at the performance issues with Direct Mode reported since 0.4.3:
https://answers.unrealengine.com/questions/124299/451-capped-at-375-fps.html
https://answers.unrealengine.com/questions/141818/ue-460-and-oculus-043-huge-bugs.html

I could run my scene at "hmd sp 140" on 0.4.2 Direct Mode (no mirroring) with solid 75 fps, but now in order to have it playable on 0.4.3 / 0.4.4 i have to go down to "hmd sp 110" in Direct Mode (or "hmd sp 120" in Extended Mode).

Not to put to the blame on anyone, but the Epic guys are basically saying that this is a problem with the Oculus runtime, not UE itself:
https://forums.unrealengine.com/showthread.php?53377-UE-4-6-0-and-Oculus-0-4-3-huge-bugs&p=191978&viewfull=1#post191978
"Nick Whiting" wrote:
I know it's been mentioned in other threads, but please be aware that many of these bugs are with the Oculus runtimes, and not the engine directly. We tested our internal benchmark demos, and saw the correlation of framerate was tied to the revisions of the SDK rather than revisions of the engine. In extended mode, there was no difference between engine and runtime versions.

In direct mode in some configs, if you can't maintain the 75Hz needed to maintain, the framerate might drop to 37.5 (half the screen refresh rate). We've noticed that if your config has issues with Direct mode, Extended mode is often much better. As Oculus revises their runtime, this should get much better!

Like i said in the UE forums, if in the end this is the price that we have to pay in order to have lower latency and we can't have both performance and low latency at the same time, then i would suggest to at least make it optional (something like ultra-low latency mode vs performance mode), or simply having some flag that we could enable/disable.

Thanks!
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    7 replies

    getnamo
    Up and Coming
    December 13, 2014
    I second this, both the performance and usability of the plugin should be addressed.
    Current Project: Skycall
    artyom17
    Up and Coming
    December 14, 2014
    I'd recommend to test performance in Extend mode and compare with UE4 4.3 or 4.4 (when 0.4.2 was integrated). If you get the same performance in 4.6 + 0.4.4 (0.4.3) in Extend mode and lower performance in Direct mode then yes, it is our fault. It is known that Direct mode steals about 10% of performance, and we are working on improving Direct mode performance and hopefully soon it won't be slower than Extend mode.
    PatimPatamAuthor
    Up and Coming
    December 14, 2014
    Thanks for the reply artyom.

    "artyom17" wrote:
    I'd recommend to test performance in Extend mode and compare with UE4 4.3 or 4.4 (when 0.4.2 was integrated). If you get the same performance in 4.6 + 0.4.4 (0.4.3) in Extend mode and lower performance in Direct mode then yes, it is our fault.

    Yep, in Extended Mode i have exactly the same performance between 0.4.2 and 0.4.3.

    "artyom17" wrote:
    It is known that Direct mode steals about 10% of performance, and we are working on improving Direct mode performance and hopefully soon it won't be slower than Extend mode.

    I think what me and other people find a bit frustrating is that in 0.4.2 we did have better performance in Direct Mode than in Extended Mode and we optimized our games for that.

    After 0.4.3 we lost that extra performance of Direct Mode, and Extended Mode stayed the same.. so an experience that was running smooth and crisp before now has to be somehow compromised.. it's always hard to go backwards, specially when you are fighting for every frame like we do in VR.

    Direct Mode + Aero OFF + Mirror OFF is the configuration that gave me the best performance pre-0.4.3 which just doesn't work anymore (between 0 and 1 FPS), and the alternatives are much worse in comparison.


    Anyhow.. i guess i will have to get used to working with a blurrier image until things improve on the software and/or hardware side.. i will stop whining now. Thanks again!
    artyom17
    Up and Coming
    December 16, 2014
    I've just talked to our video driver dev and he suggested to leave Aero ON: this should give better perf and avoid the issue with MIRROR OFF performance.
    PatimPatamAuthor
    Up and Coming
    December 16, 2014
    Yes if i leave Aero ON i don't have the 1 FPS issue, but performance is still much worse than it was with 0.4.2 and Aero OFF .

    Direct Mode 0.4.2 Aero OFF i could render scene with screen percentage = 140 at locked 75 fps vsync
    Direct Mode 0.4.4 Aero ON i have to render with screen percentage = 110 in order to get the same 75 fps

    (you can see my profile captures on the first answerhub thread)
    artyom17
    Up and Coming
    December 16, 2014
    Don't remember for sure, but 0.4.2 might not have zero post-process latency. As I described in another topic, this is what causes big difference in FPS between Extend and Direct mode.
    BTW, have you tried to enable parallel rendering? In the case if your game is CPU bound this may help. You need to uncomment the following line in Config\ConsoleVariables.ini:


    ; Uncomment to enable parallel rendering at startup
    r.RHICmdBypass=0    ; UNCOMMENT THIS ONE
    PatimPatamAuthor
    Up and Coming
    December 17, 2014
    "artyom17" wrote:
    Don't remember for sure, but 0.4.2 might not have zero post-process latency. As I described in another topic, this is what causes big difference in FPS between Extend and Direct mode.

    Yep that explains part of it i guess, in 0.4.2 Direct i get pp=13.5 ms, same as Extended.

    The curious thing is that in 0.4.2 i had about 10% better performance in Direct Mode compared to Extended, that's why having now 10% less feels like a big drop.

    "artyom17" wrote:
    BTW, have you tried to enable parallel rendering? In the case if your game is CPU bound this may help.

    Nope it didn't seem to make any difference.. Thanks for the tip anyway!
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