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Guest Rex247

Variable frame rates

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I'm asking this because a lot of you are veterans that have had years to understand the sim, and though I've done my research and experimentation, I've only had it for less than 2 weeks. Why does the frame rate fluctuate so much and why is it so different in one location compared to another? Sometimes, it's the scenery, sometimes the weather, sometimes the traffic but I haven't made a connection yet with one location a stone's throw away that runs swift, while the one I just flew from is running at 8 FPS. I don't want settings. I just want to understand why this is happening. Thank you.

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I'm asking this because a lot of you are veterans that have had years to understand the sim, and though I've done my research and experimentation, I've only had it for less than 2 weeks. Why does the frame rate fluctuate so much and why is it so different in one location compared to another? Sometimes, it's the scenery, sometimes the weather, sometimes the traffic but I haven't made a connection yet with one location a stone's throw away that runs swift, while the one I just flew from is running at 8 FPS. I don't want settings. I just want to understand why this is happening. Thank you.
It is really simple, as you noted, FSX is doing alot of stuff.  Some functions like AI are especially hungry, AutoGen is another.  The problem is that when these guys have to do some work, it is not evenly distributed, (AutoGen runs in batches) so you will see the wide FPS swings.  We all want a smoooooth and responsive sim more than anything.You can test this yourself when you are landing your favorite plane at your favorite airport.  Is it smooth and believable?There is no love in counting FPS except sometimes they shoot really high and you wonder what you did to change it.Cheersjja   

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Why does the frame rate fluctuate so much and why is it so different in one location compared to another?
You already have the answer from the previous post, but unless the plane becomes unresponsive and unflyable, I'd say: Do not worry about it.If an area brings your system to it's knees, it is worth trying some things to find the main culprit, just so that you can dial it back for the next time. Start by reducing traffic, even just setting road traffic to zero can help a lot.

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You already have the answer from the previous post, but unless the plane becomes unresponsive and unflyable, I'd say: Do not worry about it.If an area brings your system to it's knees, it is worth trying some things to find the main culprit, just so that you can dial it back for the next time. Start by reducing traffic, even just setting road traffic to zero can help a lot.
But that's the thing. Sometimes cars don't effect my frames at all, but scenery does. I have autogen off. Then I go somewhere else, and suddenly it's the opposite. I don't understand why a few airport buildings could stress my system so much. Maybe it's the plane AI. I just never know because it keeps changing. Maybe it's my addons. Its so tough to tune for this.

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Can I also ask what features the GPU solely manages? Since more work is done by the CPU, I want to at least maximize the work my GPU does. Or does the CPU have a part in everything anyway? Is the CPU actually being used to render graphics??

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Can I also ask what features the GPU solely manages? Since more work is done by the CPU, I want to at least maximize the work my GPU does. Or does the CPU have a part in everything anyway? Is the CPU actually being used to render graphics??
It sounds like you need to get ahold of Microsoft's two tools, Process Monitor and Process Explorer and you can see for yourself what's happening while running FSX.Best regards,Jim

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Can I also ask what features the GPU solely manages? Since more work is done by the CPU, I want to at least maximize the work my GPU does. Or does the CPU have a part in everything anyway? Is the CPU actually being used to render graphics??
CPU : Use parameters and create flight model "state" Apply weather model to flight model calculate where the plane will be next step Same for all the traffic, planes and cars Determine point of view (where are you looking) Determine the list of scenery object visible Apply mips rules depending on line of sight to texture list Determine list of mesh objects visible Determine cloud movement (which textures)and where Create autogen list - create texture list Collision detection Apply animation models to current view (smoke etc, wheels) Adjust all guages to reflect flight state Determine shadows - ray tracing Water texture list - reflection ray trace(x2 setting) Detect sound list files needed Do AA if set to application, and apply to textures Push textures to main bus to GPU push sound reference to sound cardMain bus - move texturesGPU Pull texture list from bus (depends on buffer pools) Apply sync rule - to identify a single scene of textures Apply mips mapping to textures (if not application set) Apply AA to textures (if not application set) Apply Z-buffer sort to texture list (draw order) Render textures to back-plane buffer (not-visible) Re-render the water animated effects textures Re-render the blume effect textures Swap buffer (put back-plane buffer to front buffer)You can control the balance of work by setting AA and AF toeither application or GPU. Everything else is the balanceof the number of textures to work on - and this depends on yourslider settings.The entire process is a balance of the CPU intensive items (moving the plane, and moving traffic, collision detectionand point of view -line of sight calculation) and the texturegeneration. The CPU must work out the list of textures, andthe GPU must draw them. The main bus must move the textures, sothis is where a slow bus speed or RAM speed can effect things too. I am sure I have missed something too.Edit : line of sight heavily effects the work load as the list of textures needed will changeif you look somewhere with a lot of busy things.This will cause large changes in fps

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Thanks Firehawk and Tom for the information. I did a lot of tests last night at KJFK, one of the heaviest areas I've been to. After turning various sliders down, I noticed I got the most performance from disabling airport vehicles, which is strange because I thought AI planes would affect me more. They were second on the list, so I'm going to fly with them both off and look for some replacement aircraft that won't put such a large footprint on my system. However, when I flew over NYC, with autogen off, I had a big hit. I thought it was strange, so I turned scenery complexity to very sparse. I still had a performance hit with very few buildings around. I haven't tested it yet, but I have a feeling it was AI cars. But like I said before, It must be location specific because cars don't affect me like this in other parts of NY. This is still just fair weather! I'm going back to testing now.

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Remember that there are three big airports within a 15 mile radius in New York, with multiple smaller strips as well. This is probably the reason for quite a bit of the slowdowns

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Rex247,I would suggest you read NickN's guide on how to setup and tune FSX.It can be found here:http://www.simforums.com/forums/setting-up-fsx-and-how-to-tune-it_topic29041.html

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Another trick that I use when landing at or near big airports is to toggle AI off (ctrl+shift+T) in UTII.  This helps to ensure that the landing will be smooth.  Clouds are another killer so you can load a 'clear' weather theme to factor them out.These tricks come under the heading of 'make the sim do less'.jja

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Can I also ask what features the GPU solely manages? Since more work is done by the CPU, I want to at least maximize the work my GPU does. Or does the CPU have a part in everything anyway? Is the CPU actually being used to render graphics??
Rex, The insights as to what causes frame rate fluctuations appears to have been addressed already. Take a look at my system specs. This is a two year old box. But is fairly optimized. I am able to run very complex situations w/ payware commercial jets in a very very smooth and performance-friendly environment. You have to pay your dues, but it's worth it, if you have the horsepower under the hood to handle it. Compare your machine w/ mine and see what you think. I am currently running at 3.88Ghz as there was just no advantage to 4.0+Ghz when you considered changes in performance versus power requirements (and heat management). I am a little paranoid on hurting my processor, and I do care because I have no need to upgrade the platform--it is already great.Bejote's tweaks provide the most potent improvement in the sim IMO. It takes over where other approaches begin to hit the wall, and takes you right up to max capability....for your particular machine. Be sure to test FPS_Limiter as well. It's a wonderful utility but doesn't enjoy universal benefit.Noel

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@wims, I didn't get the same spike in DX10. I think the water was the culprit. I'm kind of surprised that DX10 has a bigger problem with scenery though. I was running unlimited frames at KJFK, vsyncing at 60hz, and as soon as I turned bother water and scenery up, my frames got halved! As I said before, FSX(DX9) performance was not changed much by scenery. I haven't checked what difference AI makes yet.@sargeski, its a good guide but I much prefer tweaking myself. I've learned a lot of things in doing so.@jjallen, I haven't tested around cumulonimbus lately but I fly through smaller clouds all the time with no problems.@Noel, you've beaten me in speed but we have similar systems. I run a Q6600 @ 3.4Ghz on a P35-DS3L motherboard, an HD5850 stock clock and 3.5GB of DDR2. You definitely have a faster HDD than me. What I need right now are DX10 tweaks, because I know by the frames I was getting that I have potential to fix all of this.

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