Vsync without triple buffering and fps

[SteveW 1,792]

Whether the VSync get's through is down to the hardware and possible other things. For example, there's a thousand different combinations of monitor, settings and cables so what actually results needs testing on a per system basis. Next, if the system is mis-behaving in some way be sure the right settings are made, but first do a Restore/Apply on those profiles - very often the code in the profile can mis-match and cause odd behaviour so always start fresh..

Edited November 25, 2018 by SteveW

[SteveW 1,792]

...look for doubling. If fps is double or half what you expect - suspect a fault in the VSYNC area.

[SteveW 1,792]

So we are still correct to say that VSync=On in P3D Display Settings steers the GPU output to near the Monitor Refresh Frequency. However, remember we are not talking about vertical sync here, that's under control of the desktop, P3D only ever shows a window, even at fullscreen. VSync=On in P3D attempts to understand the time of the next frame on the monitor - anything can happen down that chain. When the next frame is completed it can take any amount of time - hence the wobble.

 

 

[joepoway 241]

2 minutes ago, SteveW said:

So we are still correct to say that VSync=On in P3D Display Settings steers the GPU output to near the Monitor Refresh Frequency. However, remember we are not talking about vertical sync here, that's under control of the desktop, P3D only ever shows a window, even at fullscreen. VSync=On in P3D attempts to understand the time of the next frame on the monitor - anything can happen down that chain. When the next frame is completed it can take any amount of time - hence the wobble.

 

 

This I understand but will using the Vsync On setting in Nvidia Control Panel actually control the Verticle Sync to what it is set at? It doesn't seem to work any differently in my set-up, I still get the "wobble" around 30 FPS. It seems neither application of Vsync actually controls the Verticle Sync in P3D but only attempts to understand it as you say, hence the "wobble" in either case whether using P3D, NCP or both set to Vsync ON.

Joe

[SteveW 1,792]

34 minutes ago, joepoway said:

This I understand but will using the Vsync On setting in Nvidia Control Panel actually control the Verticle Sync to what it is set at? It doesn't seem to work any differently in my set-up

If you recall I mentioned vertical sync is under control of the desktop and that the P3D viewport is only ever shown in a window. In fact P3D does not use Exclusive Mode - the special game display setup that Windows can do that is more in tune with programs that only have a single view. P3D opted to use the Window view as an overall solution to some problems in that area. So no, that's not going to affect P3D, however that might affect operations in some way, so that must be inspected on a per system basis. That setting with the half refresh etc is for Exclusive mode but don't rule out it having an effect somehow.

VSync=On is such an important setting not necessarily what we might ultimately use, since there's locked fps too, although we do usually use VSync because of the performance requirements of locked is so high. It's so important that not using or understanding it is a mistake since it shows the behaviour of the setup from Unlimited fps. Ultimately showing us if we have Overhead in the system by seeing the fps drop and the CPU use drop when VSync is switched on. Understanding that goes some way to understanding how P3D works.

 

 

Edited November 25, 2018 by SteveW

[SteveW 1,792]

...Setting locked fps and seeing the fps drop is not the same at all as setting VSync=on. The locked fps setting continues as if Unlimited since it makes Look-Ahead frames as soon as the one showing is completed.

[SteveW 1,792]

Those few paragraphs are key to setup of your sim. Armed with that information, keep an eye on Task Manager CPU graphs, and creep up the settings till you nearly max out the main core and then drop those settings a notch. This leaves overhead in the system so when the going gets tougher on the display you remain with a stable(ish) fps because you also see the CPU creep up as well. If that's already maxed - it's at or near 100% on one core, what you need to know is that it slows down in key areas to keep things going. Simple analogy: When you are at max throttle you can't climb faster to match a downdraught.

Edited November 25, 2018 by SteveW

[SteveW 1,792]

9 minutes ago, SteveW said:

...Setting locked fps and seeing the fps drop is not the same at all as setting VSync=on. The locked fps setting continues as if Unlimited since it makes Look-Ahead frames as soon as the one showing is completed.

Since it might already be making a next frame look-ahead, that eats into the time it would have taken on the actual next frame. And so that shows worse performance - only use when you can be sure of exceeding the fps set by a good margin - we use unlimited VSync=Off to check that - it is a test mode.

[SteveW 1,792]

I'm not reporting some ideas or opinions. Instead i'm showing how the stuff works so that we can problem solve for ourselves. If we get dis-similar results we need to inspect the system. Since anything can be reported - doesn't happen for me - does not mean that lot above is just garbage. Instead we have a system that is not set up the same.

For example. Imagine a 60Hz monitor and a setup of P3D that outputs around 35fps maximum. So we set On VSync and find no changes. Is the information given wrong or do we have an error in the setup? When you get the different result look to why that is, don't tear up the rule book and discover an ambiguous setting on the monitor caused the error.

[joepoway 241]

33 minutes ago, SteveW said:

If you recall I mentioned vertical sync is under control of the desktop and that the P3D viewport is only ever shown in a window. In fact P3D does not use Exclusive Mode - the special game display setup that Windows can do that is more in tune with programs that only have a single view. P3D opted to use the Window view as an overall solution to some problems in that area. So no, that's not going to affect P3D, however that might affect operations in some way, so that must be inspected on a per system basis. That setting with the half refresh etc is for Exclusive mode but don't rule out it having an effect somehow.

VSync=On is such an important setting not necessarily what we might ultimately use, since there's locked fps too, although we do usually use VSync because of the performance requirements of locked is so high. It's so important that not using or understanding it is a mistake since it shows the behaviour of the setup from Unlimited fps. Ultimately showing us if we have Overhead in the system by seeing the fps drop and the CPU use drop when VSync is switched on. Understanding that goes some way to understanding how P3D works.

 

 

Thanks Steve I get it now.

I know Rob has shown the "Blurries" issue with running unlimited but I still find Unlimited with Vsync and TB turned on to be the best settings for my 30Hz 4K monitor and system. I also do all of these in the P3D settings and not out in NCP I just use NCP to set Preferred Max Performance and Clamp the Negative LOD bias.

Joe

[SteveW 1,792]

17 hours ago, joepoway said:

Thanks Steve I get it now.

I know Rob has shown the "Blurries" issue with running unlimited but I still find Unlimited with Vsync and TB turned on to be the best settings for my 30Hz 4K monitor and system. I also do all of these in the P3D settings and not out in NCP I just use NCP to set Preferred Max Performance and Clamp the Negative LOD bias.

Joe

Talk about "Unlimited" means unlimited fps. With VSync=On you are "Limited" and if you follow my advice setting up for Overhead, your system will be fine.

[joepoway 241]

1 hour ago, SteveW said:

Talk about "Unlimited" means unlimited fps. With VSync=On you are "Limited" and if you follow my advice setting up for Overhead, your system will be fine.

Steve,

First, thanks again for all the knowledge and information you contribute to this forum.

Your reply is interesting, so in the testing that Rob did showing Unlimited induced "blurries" only applies when you do not have Vsync On?

That would imply as far as P3D is concerned an internal frame limiter like 30 FPS or Unlimited with Vsync on a 30Hz monitor that shoots for 30 FPS  would not induce the "blurries" that Rob discovered, only unlimited with no Vsync, is this what you are saying?

That's good news if true.

Joe

[SteveW 1,792]

 

6 minutes ago, joepoway said:

Steve,

First, thanks again for all the knowledge and information you contribute to this forum.

You're welcome! I get plenty of grateful mail and feedback - thanks again friends - and no-one ever seems to have a problem so I must be doing something right. 😊

 

10 minutes ago, joepoway said:

Your reply is interesting, so in the testing that Rob did showing Unlimited induced "blurries" only applies when you do not have Vsync On? 

That would imply as far as P3D is concerned an internal frame limiter like 30 FPS or Unlimited with Vsync on a 30Hz monitor that shoots for 30 FPS  would not induce the "blurries" that Rob discovered, only unlimited with no Vsync, is this what you are saying?

 

Generally that is the case yes, and if it is not we look for a problem. Since there's plenty of other things that can cause blurriness, ( I presume Rob means textures not fully read-in that is ). Simply forgetting to Restore/Apply on the P3D profile after trying certain changes in it or quite often just having updated the driver can cause odd behaviour. So we say that the regular system does what we expect and if that's not happening we look for reasons why. Reduce to one window, remove undocked panels, there's plenty of possibility there to fool the VSync side. Look for doubling or halving in fps this usually means a VSync error and the Restore/Apply fixes it. That's the usual one.

[SteveW 1,792]

What we can do is switch the view to an AI aircraft in flight somewhere and we can see the speed that the new terrain area loads up, that will often be blurry at first. If that's happening all the time on a system in the User view then there's some contention in the system slowing down or causing part of the P3D process to wait.

As I said there's lots of ways to upset the system. This behaviour can sometimes be simulated by messing with application Priority. Setting the sim to higher priority or trying game-mode results in certain parts of P3D waiting longer for the processes that are now reduced in priority and reduces performance.

[SteveW 1,792]

Also, how many PCs would you run on one motherboard, since each core represents a virtual PC. P3D isn't the same as Paint3D and doesn't run like, a good example is the video renderer which can allocate a frame to each core. P3D will use as many as you give it - no AM means all cores will run, most loading scenery How many cores can you run off one scenery storage system that is time critical? Doesn't matter how long each frame takes to create with the video renderer, and we can go and put the kettle on when loading Paint3D on an older system. So with many cored systems P3D requires careful setup, we need to tell it the partition with the AM setting or the system bandwidth can become saturated and we see slowdowns not speed-ups.