DCS Performance, FPS Drops and Stuttering

Still experiencing FPS drops every 4 seconds exactly to 30/40 FPS temporarily, otherwise the game remains at a solid 55-65 FPS.

This is an issue which also existed in previous versions 1.0 and 1.5. I've tried literally everything on forums, and various options to no effect.

I am able to increase FPS by reducing graphical options, but the drops to 30/40 FPS occur every 4 seconds regardless, which causes a noticeable stuttering effect.

It's obviously a multi-threading issue, since all 4 CPU cores are running at 25-50%, while it occurs regularly every 4 secs, suggesting threads are being blocked.

Side note: Attempting to alter shadow options in v2.5.4.29167 causes the game to crash once while loading, but it does not crash again after restarting.

Also note: VR options were enabled by default, and had to be disabled because they were causing cockpit mouse view issues (stuttering).

Whilst I fly VR DCS 2.5 stable, I still don't see that issue.

Could it be your hardware/software/settings causing an issue?

Flying the Open Beta on a SSD with a 4670k (@4.4GHz), 16GB of RAM and GTX 1080 Ti and I'm not having any issue.

Well, I think I've figured out what the issue is. The GPU has 2GB vram. Unfortunately, I don't plan on upgrading it before AMD Navi core cards are out.

Setting Terrain Texture Resolution to Low seems to fix the problem, but looks horrible. Unfortunately, there is no 'medium' graphics option, and reducing the preload distance below 50/60k is not realistic.

Thus, the thread blocking every 4 seconds is probably the one doing the preloading. Maybe that can be improved somewhat.

Beta, this issue of regular stuttering was often related to harddrive r/w speeds not being high enough. Mine used to do it, too. If you're not using a SSD that may very well be why. The maps etc are just too big for a conventional HD to load smoothly.

Also, DCS doesn't use more than two threads, you having 4 cores at whatever is irrelevant. That's also not necessarily what that means either, as it's a way of averaging, not a hard fast 'you're using 50%' because it's apt to be constantly cycling between cores. Anyway that's a whole 'nuther topic.

2GB of VRAM would do it,.. :D

Yeah waiting to see what Razen 3000 and Navi bring to the table too. :thumbup:

Nah, I run Raid0, which is like 90% read speed of an SSD at 1/10th the price for capacity, sequential not random though. Ought to try Raid0 SSDs though.

Furthermore, an SSD may reduce the preload times, and thus the amount of stutter but will not eliminate it completely, especially if the GPU doesn't have sufficient memory.

In fact, even if it does have sufficient memory, you'll probably get some stuttering when the texture is first preloaded at the preload distance, assuming it is never flushed, doesn't matter how good your PC is, due to the way it's blocking the graphics thread.

Although, in a high performance scenario, it would be best to max out preload distance, to minimize the amount of preloading, as long as memory permits.

2GB of VRAM would do it,.. :D

Lol, still runs all games on High graphics settings at 45-60 FPS, without stuttering. ;o

Well, if the price isn't good enough, they'll probably cause a price drop on Vega GPUs anyways, so it's always better to wait a few months. ;p

Again in my observations yes DCS might run 2 threads but Windows is utilizing more CPU usage and DCS is also indicating more CPU usage in Task Manager since recent Windows/Rift/DCS updates. I am not claiming DCS is "more multi-threaded" but it seems Windows is able to utilize more CPU usage.

As for HDD/SSD usage with 32GB of system RAM and 1080Ti/2080Ti I really don't see any harddrive/pagefile usage above the occasional 1% periodically in game SP or MP which is more likely the OS doing it's housekeeping thing.

:)

Nah, I run Raid0, which is like 90% read speed of an SSD at 1/10th the price for capacity, sequential not random though. Ought to try Raid0 SSDs though.

you are so wrong

32GB RAM doesn't give you much these days, maybe in some games, which actually make use of the 64-bit address space. Most 64-bit games though, still address only 4GB of RAM, using a 32-bit address space translated to 64. Not sure what the case for DCS is though, but is simple enough to profile.

I have 16GB in this rig, used mostly for video/sound editing, otherwise 4GB gets used by games, 8GB by windows, and 4GB remains free. I think I once found a game that used 8GB. ;\

you are so wrong

Wrong about what? 300MB/s being 86% of 350MB/s? Close enough... we're not talking about top of the line SSDs here, but you could just Raid0 two cheaper SSDs, paying half price for capacity, so who cares.

DCS will happily use 12GB+ RAM and 10GB+ VRAM in MP,.. :)

Raid 0 breaks easier from personal experience,.. :cry:

Only had 1 Raid0 array break, due to a faulty disk, setup over 10-12 of them. Easy enough to fix with a system image though. Also keep documents on a Raid1 file server with backups, too cheap to build a Raid5/10 array for documents.

DCS will happily use 12GB+ RAM and 10GB+ VRAM in MP,.. :)

Just checked, my DCS is using 4GB. Although, that's in 1920x1080 SP. I'd imagine VR only uses more VRAM not system RAM. I tried Low/High resolution textures and it didn't make a difference. DCS.exe still uses only 4GB RAM, while I have 4GB free (12GB system commit, which includes 8GB OS/apps and 4GB DCS).

on hoggit my ram usage is easily around 22GB

on hoggit my ram usage is easily around 22GB

Are you sure that's RAM usage though? or 'virtual size', which includes pages on disk? I can only see DCS using 4GB max, but the virtual size is indeed 22GB, which are mostly memory-mapped game asset files I am assuming, although that would require verification. I doubt the 22-4=18GB are related to the page file because my page file is only 16GB.

Hmm, I'm seeing other reports of RAM creeping up to 8-12 GB, but then usually leading to bad performance or crashes, maybe those are just leaks? Not sure.

nope thats actual ram being used, i am running at 3440x1440 though with near everything on max so my system is pushed harder than most other games do

Just for reference: There's no way it's all page file, because DCS.exe only read 1.6GB from disk, which may be compressed assets, so the 4GB RAM I'm seeing is believable, but not the 22GB virtual being page file. They must all be memory mapped files, although I've never discovered a method to determine that.

Ah ok, yes, in Process Explorer, show Lower Pane, and the memory mapped files will all be listed there, pretty much includes all of the game assets.

They're essentially files that are not in use, but can be paged into memory at any time. Essentially, when the assets are preloaded by the game at the preload distance. More assets = more RAM+VRAM, or at least more 'allocated' RAM (which isn't necessarily in use at the time). Higher resolutions = more VRAM.

The highest RAM usage I've seen in SP 1920x1080 thus far is 5GB, with 23GB virtual size (which include all of those assets 'allocated' but not in use).

Hmmm, something else I found odd. The internal game FPS counter reports video mem increasing from 3GB to ~8GB, as if it's not being cleared, or simply cached/paged. However, Process Explorer only reports 1.2-1.8 GB dedicated GPU memory and 500MB-3GB committed (with low res terrain textures). So the in-game counter isn't exactly reliable in terms of memory actually in use at the time.

Basically, when loading a new map, it is not clearing whatever assets it had preloaded? This seems to be the cause in my case, as when it's at 3GB I get nearly no stutter, but after loading 3-4 maps it creeps up to 7GB I get constant FPS drops (although Process Explorer still reports only ~3GB max usage). With high resolution terrain textures, that occurs immediately. inb4; this is only a 2GB card.

For reference (high res terrain textures): Begins at 4GB VRAM usage (where the stutter begins on a 2GB card), and creeps up to 9GB and beyond (after loading 3/4 maps and aircraft). These numbers may vary for higher resolution maps, which I don't own and can't test. These were tested in Flaming Cliffs 3 Instant Action missions.

As a temporary fix/workaround: Just restart the game to clear the assets from RAM/VRAM. Although that will increase mission load times.

Still odd that the system is paging to disk at 1MB/sec though (writing to pagefile.sys), while there are 2-4GB RAM remaining. It does this constantly, even while the game is paused. I can't come up with a valid explanation for this phenomenon... DCS.exe continues to utilize 25% CPU while paused (mainly rendering). I can also confirm it's DCS causing the page faults via its Page Fault Delta.

DCS will happily use 12GB+ RAM and 10GB+ VRAM in MP,.. :)

DCS eats 7GB RAM + 3,5GB VRAM already on the absolutely lowest settings possible (with blurry textures like 20 years ago) on an empty map. 1920x1200.

Also, DCS doesn't use more than two threads, you having 4 cores at whatever is irrelevant.

Actually, just confirmed this too. It may not have been the case in the past, but now DCS.exe is spread across all 4 cores. It is the top process on each core, using 25-50% of its cycles. Affinity is also set on the process by default for all 4 cores. DCS.exe is also executing 31-34 threads; multi-instance (TIL), multi-threaded.

I wound up building a new computer with 32 gig ram and upgraded my 2600K cpu. The 1070 gamer video card has worked fine and I put in a SSD, why it got rid of the stutter I'm not sure but it did.

1070

I'm assuming it's the 8GB VRAM on the 1070, which appears to be a baseline minimum for DCS. A slightly faster CPU and more RAM are always useful though so they don't bottleneck the GPU, up to a point, not sure if 16GB vs. 32GB RAM makes that much of a difference (various opinions on this topic).

It can run on 2-4GB VRAM (using low resolution terrain textures), but it's not clearing the assets, so you have to restart the game each time to reduce VRAM usage before starting another mission. Same applies if you experience stuttering on 6GB-8GB cards on higher resolution maps with high resolution terrain textures, game might require a restart.

It doesn't completely eliminate the stuttering, but reduces it to events every 15-30 secs instead of every 3-4 secs. You can reduce it further using other methods like SSD, etc... but it's essentially an engine issue blocking the graphics thread that is causing it, which requires a developer fix.

Some users in another thread claimed ED found an issue in the terrain engine, with a fix due out later this year. Not sure how accurate that information is though.

Straight from Wags .

https://forums.eagle.ru/showpost.php?p=3869786&postcount=2333

Actually, just confirmed this too. It may not have been the case in the past, but now DCS.exe is spread across all 4 cores. It is the top process on each core, using 25-50% of its cycles. Affinity is also set on the process by default for all 4 cores. DCS.exe is also executing 31-34 threads; multi-instance (TIL), multi-threaded.

This is interesting, since I just tried OCing my CPU which basically runs at 3.4 / 3.8 (max boost for up to 2 cores) to 3.8 / 4.4. I saw it spiking up to 4.4 every now and then until I fired up DCS where it just locked at 3.8 straight. Which it normally wouldn't if it was just using 1 or 2 cores. Nothing else was taking up big amounts of CPU usage, totals under 10%, mainly by driver related S/W (audio consoles, TIR, TARGET and such). That might explain my recent frame rate drops, especially since that overclocking gave me more percentage in fps back than it actually was compared to the original clockings (~11.7% more clock rate, fps increase was 20-30%ish, sometimes even more than that). I'l probably just try to run all cores at 4.4 or at least 4.2 soon... I've seen lots of reports of the 3570Ks running at 4.5 - 4.7 easily. I shouldn't waste that