Is this a DCS program limitation?

[jasonstory44]

Recently had a motherboard melt down and had to build a new rig from the ground up. As crushing as that was it was also exciting as it was a chance to improve my VR performance in my Vive Pro (while I wait for the Reverb to get its act together).

Got a 9900 k delidded which overclocks nicely to 5.1 MHz and added a Titan RTX overclocked and water cooled. Also added Corsair Dominator Platinum ram (3400 MHz and 64 mb). Figured that would give me some good punch and extra breathing room.

 

The performance is certainly improved and decent...but far from perfect. In trying to figure out my limiting component I simply can’t. No core is maxed out...actually highest runs at 35% usage. Obviously plenty of ram. And my Titan says it is only using 9 mb of ram and max 60-65 % usage.

 

Yet SteamVR shows my frame times around 28-31 ms. Obviously reprojection is kicking in. And yes I have most of my settings maxed out.

 

This isn’t really to complain about the performance more a question of what the limiting factor is. Is it DCS code? Is this a SteamVR problem?

 

On my old machine I could see I was frequently maxing out my processor (albeit at 4.4 mhz) as well as my old Titan Xp card (often hitting 90-100% usage).

 

I know I could turn off shadows and turn off MSAA (from 2-0) but the addict in me really wants to push it.

 

Interestingly enough, turning most settings up does very little to deteriorate my performance. Guess I should be grateful for that.

 

Any insight or knowledge greatly appreciated.

 

Cheers, Jason

[Mr_sukebe]

I did see some comments recently about hyperthreading potentially impacting performance. Try having a look at that.

[Tinkickef]

DCS is not really fully optimised for VR. Throwing money at a rig to get a performance increase in VR; just like you, I and many others have found out, is a lesson in the benefits of diminishing returns.

 

Analogy.

 

It's like spending £20k tuning an engine, then putting it in a 10 ton truck, expecting it to do a 12 second run down the dragstrip, only to find disappointment in a 20 second run. Then spending another £20k, to find you only shaved a 1/4 second off your previous time.

 

Until you reduce the weight of the truck to a half ton or so, you are never going to see a 12 second quarter mile.

 

Same with DCS. The devs acknowledge this and are working on it. At present, the pinnacle of VR map performance is NTTR.

Edited August 8, 2019 by Tinkickef

[Sandman1330]

It sounds to me like you are still processor limited. The way windows scheduler bounces the thread between cores, it happens so fast that you never get a reading of 100% on any core.

 

Try this experiment: lower all settings to minimum and note your FPS. With your proc, it will probably max at 90, your HMD max refresh rate. Then add eye candy settings one at a time (textures, MSAA, PD) and note your FPS. At some point (probably with lots of eye candy in your case), your FPS will start to drop. This will be your GPU maxing out. Slightly back off from that point, and you will have a good balance (both CPU and GPU running full).

 

This is more pertinent to those with weaker processors (like when I had my 1600X), but may still work in your case.

[jasonstory44]

Lots of good suggestions. Thanks guys

[Harlikwin]

While my rig is a bit more modest, yeah, VR frame rates still aren't great. But on the plus side you should be able to run the reverb without much issue since I can. The biggest thing I found was that because I could lower PD without any real reduction in scene quality, I could turn stuff up compared to what I was doing with my CV1 rift. Which sounds kinda nuts, but its true.

[jasonstory44]

Yea again wasn’t really complaining. My performance still seems enjoyable. Just trying to figure out where and what’s limiting me. Interesting turning down a bunch of stuff doesn’t really seem to affect my frame time in SteamVR in the positive direction. And nothing seems maxed out on my system other than my frame time being choked out. GPU z seems to suggest my voltage reliability is capping my GPU but since I have my power maxed out in overclock guess that’s all I’m gonna get.

 

As with all things in DCS it’s fun to learn and experiment. That search for perfection can be all consuming at times though.

[Bephott]

I always thought it's some kind of artificially generated headroom by DCS, so your GPU is not running at 100% performance, but has extra capacity to handle something like a bunch of explosions. The problem is that, this is just not enough for VR, where the GPU has to serve 2 displays. They optimized something about this recently, but high settings and 90fps are still not possible (for most situations).

So the 2 options are: high fps at lower settings or higher settings with reprojection (or AWS).

I just decided to go for higher settings and quickly got used to the 45 fps.

Btw, I tried many settings and I don't think MSAA and shadows are the most demanding settings. I found high visible range to be much more problematic!