tdm_lg_split on by default?

[nbohr1more]

tdm_lg_split is an option split the lightgem calculation between alternate frames (eg. do half of the calculation in one frame and half in the other) as compared

to tdm_lg_interleave which skips a number of frames for calculating the lightgem. The two cvars can be used together as they perform independent functions.

 

It was reported in the past that tdm_lg_split caused flickering, mostly for particle effects. Since 2.03 introduced Soft Particles (also particles no longer render during lightgem processing)

, this does not appear to be the case.

 

Please confirm whether this setting (in Darkmod.cfg) causes flicker for you.

 
seta tdm_lg_split "1"
 

If we aren't seeing any problem reports, we should probably enable this by default in the next release.

[Dragofer]

This causes no flicker for me even in scenes with a large amount of various types of particles.

[New Horizon]

Gas arrows were a problem I recall.

[nbohr1more]

I am not able to detect any problem with flickering gas arrows.

 

There is a sorta strobe in the effect as the color fades but it is happening when

this setting is disabled or enabled. The same is true of tdm_lg_interleave. It is not

changing the strobe\flicker at the tail end of the particle effect.

 

Can anyone else confirm ?

[Dragofer]

Gas arrow explosions look normal to me. Yes, there's a whiff of strobe if you pay very close attention.

However if the gas particle is emitted by a func_emitter it's incredibly broken, but that was already happening before I activated tdm_lg_split.

[Obsttorte]

Is the performance impact that high that it makes sense to enable it by default?

[nbohr1more]

In testing, it does produce about a 4 to 5fps when in the 20 to 25FPS ranges. Enough to make tdm_lg_interleave "2" useful (interleave = 2 can double FPS in some scenes).

 

By itself, it isn't a huge optimization in my testing but I've got an Intel i3 CPU. AMD users may see more gains because it's essentially halving the scene geometry being evaluated

and the number of pixels being evaluated on the CPU (per lg render).

 

We also have a forum report that dropping AA quality can make FPS increases that match a disabled Lightgem indicating that it's possible AA is being processed during the LG

phase so this might have more impact for players who wish to increase AA quality. Haven't done extensive testing on that yet. (I thought that "render-to-image" bypassed the GL screen

contexts but that report hints otherwise...)

 

As I mentioned, I use this as a boost to make lg_interleave useful and less prone to stutter.

 

(Hidden Agenda: I am working on dynamic lg interleave which turns on only if you are above a stutter free FPS threshold. Having lg_split on by default will make

testing more sane.)

[Bikerdude]

Does this needed to be tested on a low end machine so we get to see an difference in FPS...?

[nbohr1more]

FPS is already known to improve. What we are looking for is whether the feature causes "flickering" which is why it wasn't enabled by default.

 

Thus far we have two testers who haven't been able to reproduce the flicker.

 

Would be good if someone with Intel \ AMD GPU hardware tested too.

[Dragofer]

That would be an Intel HD Graphics 3000 here. Interestingly enough, since making perf tweaks as per the wiki (mainly texture downscaling) it pulls off 20 fps most of the time and sometimes goes into the 40's. Quite a breeze compared to the way it was pre-tweaks with all those L-sized textures.

[Bikerdude]

Would be good if someone with Intel GPU hardware tested too.

Will test on the laptop as that has a HD 5500.

[snobel]

I tested this both on my normal laptop (Core i7, HD 4600 graphics, Ubuntu 14.04) and ye olde HP Pavilion (AMD Turion ZM-82, Mobility Radeon HD 3400, Vista). Tried "tdm_lg_split 1" together with various values of tdm_lg_interleave. No change in the appearance of gas clouds.

 

On the HP, at a certain point in the training mission I'd get ~20 fps. Setting split to 1 upped that by ~10 fps. Additionally setting interleave to 2 upped it again, probably by 5-7 fps, but the value would fluctuate more. I tried setting interleave as high as 10, and fps values in the 50s started to appear - but the value would fluctuate a whole lot.

[New Horizon]

Setting interleave too high can cause choppiness and will also affect lightgem accuracy, which in turn will affect the accuracy of the AI. Don't get too crazy.

[snobel]

Sure - the game actually crashed at that setting but I discovered afterwards that the (rarely used) computer had been busy downloading 100+ updates and had run out of disk space. So I'm not sure it was the interleave setting.

[nbohr1more]

Thanks for testing snobel!

[Bikerdude]

Well I tried 'interleave 1' with 'lg_split 2' and didn't see any flickering or any weird issue with the lightgem, will trying on my GTX970 later today.

[nbohr1more]

There is no lg_split 2. lg_split is either 0 or 1.

 

(I don't recall if the this input was sanitized to turn 2 into 1 though.)

 

Thanks again.

[Bikerdude]

I tried 1 aswell, and in some location of the training mission I gained roughly 5fps.

[nbohr1more]

Nice! I think this feature is ready for prime-time now.

[snobel]

Thanks for testing snobel!

Well, thank you for saying nice things about my T3 patch on Mod DB.

 

And a big thank you in general to the Dark Mod crew for all your hard work - it's an amazing project you're running! (This needs to be said once in a while...)

[Bikerdude]

I tried 1 aswell, and in some location of the training mission I gained roughly 5fps.

Testing on the GTX970@ 1650*1080, AA-16 and AS-16, Ambient/interaction set to enhance/enhanced.

 

I'm not seeing any flickering, but also not seeing an fps increase as The training mission is already flat out, so trying Behind Close Doors instead.

 

Tried BCD and same outcome, no flickering of anything to report.

[nbohr1more]

I think I'm gonna write a "sand-bagging" article for you Biker. You need to find creative ways to slow-down your rig for testing.

[Bikerdude]

You need to find creative ways to slow-down your rig for testing.

Good idea, but even with AA set to 16 it still wasent showing a slowdown.

[nbohr1more]

Right, one thing I should do is make you a debug build so the CPU impact is much higher.

 

The other thing to do is set all your performance cvars to silly settings like:

 

r_useCachedDynamicModels = 0 (disable model cache)

r_useCulling = 0 (disable all worldspawn culling)

r_useEntityCulling = 0 (disable all entity culling)

r_useInteractionCulling = 0 (disable culling for unseen interactions )

r_useLightCulling = 0 (disable light culling)

r_useOptimizedShadows = 0

r_useShadowCulling = 0

r_useTurboShadow = 0

r_useTwoSidedStencil = 0

r_useSilRemap = 0

r_useStateCaching = 0

r_usePortals = 0 (disable VP... you know that'll be slow...)

 

Finally, you could enable Transparency AA in your driver settings to make the GPU sweat on alpha tested stuff

and disable all your in-driver optimization settings like the fast AF calculation.

[Bikerdude]

r_usePortals = 0 (disable VP... you know that'll be slow...)

That along on most maps will just kill perf across the board.