DCS World: PG + F14 RAM Usage Experiment

Flight Sims
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Well, as mentioned in the Hollo Pointe thread I was going to do a test with PG and the F-14 to see what happens with RAM usage. I have 32GB of RAM on my system.

To start with, we have to acknowledge that what the task manager indicates in Windows 10 does not represent the total usage of RAM for a process. This represents the “Private” memory if some quick math (while the numbers change constantly on my screen) matches up.

The resource monitor is our friend in this case, as we want the “Working Set” which is measure in KB.
(Remember 1MB = 1024KB)

The Working Set is defined as: “Amount of PHYSICAL MEMORY currently in use by the process”.
The numbers below are working set, converted from KB → MB → GB and are solely for the DCS process. RAM in use by other processes can be seen partially in the images.

For the purpose of this test we are using the following graphics options:

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The missions is “Divine Falcon” on Hollo Pointe North, about 2 hours in. Cue the numbers!

Stage 1: Loading to the Slot Selection Screen

We are already at 12,525,676KB / 12,232.11MB / 11.95GB
We already have hard faults, meaning Window’s is working with the page file.

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Stage 2: F-14 selected and loaded in.

Now: 14,824,364KB / 14,476.92MB / 14.14GB

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Stage 3: Cycling F2 Camera Around

Now: 17,858,936KB / 17,440.37MB / 17.03GB
Hard faults are ramping up significantly as we use up RAM.

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Stage 4: Cycling F11 Camera around the Map

Note - this stage and on would be “abuse”, just trying to push it to see how far it will go.
Now: 25,192,552KB / 24,606.00MB / 24.03GB
Hard faults continue to grow massively.

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Stage 5: Maxing Out

Here we hit the peak. Task manager is indicating low RAM and it appears we got things mainly in physical memory as hard faults have dropped down again.
Now: 26,515,724KB / 25,894.26MB / 25.29GB

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I’m thinking I should have bought 64GB instead…but to be fair, F11 flying around the entire map is not what we would call typical usage.

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Cool data collection and observations. @fearlessfrog’s puppy approves of the graphs.

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Does DCS ever unload RAM? Or does it always go up?

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It does unload, I cycled the cameras around at a quick enough pace that it didn’t get to / try to.
I re-ran the experiment a second time after going back to the DCS main menu, but not closing DCS.

The maximum ram using was around 20,000,000KB - 21,000,000KB (~20GB) only. I have to hazard a guess that more data was left in the page file. I allow Windows to automatically set the page file on my C drive since it is NVMe, and it sets about 4900MB for the page file - so potentially it could have been there.

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Victor, just to bring your attention here - it seems that it’s not entirely your system that’s at fault.
DCS PG + F14 is just hugely demanding. My DCS went unresponsive on loading the F-14 in this test, and the “re-test”, but recovered.

I was hoping perhaps you could try something that may work:
In the ME, make a blank mission on the PG map. Add one F-14B as an air start and set the slot as “client”. Save the mission, then try flying it. Since the slot is a client, it will treat it like MP and give you a slot select screen. Stay as spectator and camera cycle around, then go to the menu and load into the Tomcat. Hopefully this would be a lower-load way to “preload” the map and plane into RAM / PageFile. Then try joining the MP mission on the server. Let me know if that helps at all.

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What if the internal caching of DCS (or even Win10) won’t page stuff out until your memory is full? If you had 64GB it might fill that too, as a predictive cache.

One way to test that would be to use a dev tool to claim pages, say 8GB with 32GB physical, and see if it matters in terms of performance.

I do think more memory is nearly always better but the page swap out algorithms are complicated and can hide what the app actually wants vs needs.

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Live reply - ask and ye shall receive!
Testing with Prime95 running a couple threads and told to use 12GB of RAM.

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Windows bumped the total page file size to 14,359MB. Only loaded into F14 and first few miles of cockpit flying so far.

Edit: Using the various cameras around, performance is significantly reduced in terms of load times.
Window’s is aggressively trying to not run out of RAM, quickly paging to the NVMe drive. Ram usage hit a ceiling around 14,000,000KB but the pagefile has been pushed to 16,433MB.

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So what’s your premise? As in, are you trying to see if 24GB is enough, or that 16GB is too little etc? I could see 24 being a low area for MP and the tomcat on PG, so is this to find a threshold? (I didn’t read all the other topic :blush:)

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A mix of “How does 16GB stack up to what it wants” and “How much is enough, if you give it what it wants?”.

I closed Prime95 and DCS began taking up the RAM. Next I will try to “Sabotage” it by asking Prime95 to use more RAM than DCS has left available.

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And so I asked Prime95 to use 20GB of RAM, which caused DCS’s physical memory to be cut in half immediately - but it was paged. Pagefile size is now 24,737MB.

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I am guessing that with either a page file cap, or a slower page file - DCS will definitely crash (or at least be unresponsive for a good few minutes).

If unresponsive don’t click the screen as that seems to make it crash, at least from my past experiences.

Having closed this all down, Windows shrunk the page file to around ~5000MB again.

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I will try this asap and report back.

I think my motherboard may have a faulty ram slot as I swapped all the sticks round and gave my self 32gb again. It loaded and played beautifully. But I keep having hard crashes. On 16gb it never crashes but with 32gb I seem to get at least one harr crash every night. Worst is they seem random. Once was on the aerobatics server with at least 10 other planes around me and I hit f2 to take a screenshot and it immediately hung and made the usual “brrrrrrrrzzzttttt” and then took an age to restart and get working again. Another time I was just flying in the mig 19 on my own with not much happening around me

Take out the ram sticks and just go back to 16gb and it’s fine. I’m seriously considering getting 2x 16gb sticks and just running like that.

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The buzzing reminds me of when my graphics cards go bad, but that sounds like a clear case of a RAM issue (stick / board) for you.

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