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FPS issue on main screen (multiple GPU & multiple monitor)

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Swingy

Posts: 4

Joined: Fri Apr 28, 2017 5:14 am

Post Fri Apr 28, 2017 5:28 am

FPS issue on main screen (multiple GPU & multiple monitor)

Hi,

I'm stuck on a little problem, i'm using Isboxer for LOTRO with 6 characters.
I have 2 GPU (GTX 1080 (1screen connected) & GTX Titan X (2screen connected), with 3 screens (3x 27" 2560x1440) and my CPU is a i7 5930k OC at 4.2Ghz.
I'm using 2 screens with Isboxer, the main screen with 1 window and a secondary screen with 5 windows.
On the secondary screen (which handle 5 characters) the foreground/background FPS modifier works well, 30 background & 60 foreground, but on the main screen, despite the fact the main window got an entire GPU for it self, i'm only at 35/38 fps max, and there is no FPS limitation in game or in Isboxer for this character / region.

So i would like to get better FPS on my main screen.
I know the issue is due to the multiple monitor thing, because before i was running with all the 6 characters on 1 screen and it was fine.

If you have any tips, you're welcome.

Thanks.
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lax

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Site Admin

Posts: 7301

Joined: Tue Nov 17, 2009 9:32 pm

Post Fri Apr 28, 2017 5:47 am

Re: FPS issue on main screen (multiple GPU & multiple monitor)

Hello! There is no way for us to determine the issue based solely on your description of the problem, but yes that is a possibility.

1. To check whether multiple GPUs may be related to your performance issue, we need to see your ISBoxer Configuration. See http://isboxer.com/wiki/Configuration_Sharing and get us a paste

2. Beyond that, http://isboxer.com/wiki/HOWTO:Tweak_your_framerate#Identifying_framerate_bottlenecks describes how to use a monitoring tool to capture data from your hardware while you're having the problem. This would show if you're maxing your CPU, system RAM, GPU or VRAM -- if any of those are maxed, that would definitely result in lower FPS.
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Swingy

Posts: 4

Joined: Fri Apr 28, 2017 5:14 am

Post Fri Apr 28, 2017 8:29 am

Re: FPS issue on main screen (multiple GPU & multiple monitor)

The Titan X is maxed out (the gpu which handle 5 accounts), but i can achieve the 60 fps foreground without problem with any of the 5 slaves accounts and when i remove some accounts i can get more FPS on the main account (the main account is on the 1080 gpu, only 1 account on this gpu) but since the main account should use the 1080 i don't understand why the performance of the Titan X is reducing the performance of the main account on a totally different GPU ?!
I tried to reduce the max fps of the slave accounts, from 60 to 40 on foreground, it changed absolutely nothing on the main account.

My CPU is between 15 and 30% (each core) when all accounts are loaded in-game, so it's not part of the problem.
Ram is fine, plenty of it free.
My Isboxer configuration : https://pastebin.com/YmWgiLnT
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lax

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Posts: 7301

Joined: Tue Nov 17, 2009 9:32 pm

Post Fri Apr 28, 2017 9:14 am

Re: FPS issue on main screen (multiple GPU & multiple monitor)

Okay. The issue is without any doubt your Window Layouts.

I'll link the relevant documentation and paste specifically what you need to understand here..

http://isboxer.com/wiki/GPU_Management# ... e_monitors
Multiple GPUs: With any version of Windows, allowing a game window to move from one monitor to another that is powered by a different GPU will cause a significant performance hit.

These are not Inner Space or ISBoxer limitations; This is documented by Microsoft here under Best Practices for Multi-Monitor Displays

ISBoxer's Window Layout generator provides a Cross-monitor swapping option that can be disabled to prevent either of these performance hits.


Your current multi-monitor Window Layouts are all configured with Cross-monitor swapping enabled. This is very much "allowing a game window to move from one monitor to another that is powered by a different GPU" and is specifically why you get this performance hit.

All of your game windows are assigned to the same GPU by your current Window Layout.

To resolve this performance issue, you can use the Window Layout Wizard. Before selecting a Window Layout Style from the drop-down box, look at the right hand side of the window under the "Multiple monitors" heading, and the first option under it is Cross-monitor swapping (the whole phrase may not be visible by default). Select it, then in this setting's drop-down box set it to False. Now any multi-monitor Window Layout available in the list must use multiple Swap Groups (a group of windows that swaps with each other), which allows the game windows to be assigned to different GPUs by the Window Layout, and will remain on a monitor hosted by the correct GPU. This should eliminate the issue.
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Swingy

Posts: 4

Joined: Fri Apr 28, 2017 5:14 am

Post Fri Apr 28, 2017 4:27 pm

Re: FPS issue on main screen (multiple GPU & multiple monitor)

I have set multi-monitor Window Layout to False but with the configuration i want to use it will change nothing.
If i use multiple swap group, i will not be able to swap my secondaries slot on the main screen, which is the thing i want to accomplish. (but with 2 swap groups there is no problem, as expected)
For information, in Swap Group, when there is no Roaming Slot everything work fine (but i can't swap any window ofc) and when i set a region to the Roaming Slot the FPS drop occur again.

So yeah, if it's a Windows limitation, i can only achieve what i want by connecting all screens to the same GPU otherwise i'm condemn to have low FPS on my main screen.
To resume, there is no other solution than the double swap group or the screens on a single GPU ?
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lax

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Posts: 7301

Joined: Tue Nov 17, 2009 9:32 pm

Post Fri Apr 28, 2017 8:04 pm

Re: FPS issue on main screen (multiple GPU & multiple monitor)

If i use multiple swap group, i will not be able to swap my secondaries slot on the main screen, which is the thing i want to accomplish.

The thing you want to accomplish is exactly what I've described as being the cause for the performance hit. Your GPUs are not linked and do not share VRAM (notes: SLI/Crossfire links the cards and shares/mirrors VRAM), so performance drops because one GPU is doing all of the processing, and then transferring the buffer to the other GPU for composition. This is not so much a limitation of Windows itself as it is a limitation on the way the hardware is designed to operate for high performance...

To resume, there is no other solution than the double swap group or the screens on a single GPU ?

Multiple swap groups are required in order to have your game windows assigned to multiple GPUs. Being in the same Swap Group, they must be assigned to the same GPU. To eliminate the penalty and use both of your GPUs, you must use multiple Swap Groups. (Option 1)

The only thing you can do differently to work around the performance penalty is to use Video FX. Video FX should allow you to view the game window (as opposed to moving the game window itself) on a different GPU than is doing the rendering. This will succeed in putting your small views on other monitors without the penalty, but if you want them all to swap into the same main region, then they're all going to be rendered by that same GPU, not splitting the load as desired. (Option 2)

So to directly answer your question, there is no Option 3 ("other solution" than options 1 or 2).
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Swingy

Posts: 4

Joined: Fri Apr 28, 2017 5:14 am

Post Sat Apr 29, 2017 6:08 am

Re: FPS issue on main screen (multiple GPU & multiple monitor)

Indeed.
Well i've put both screen on the same GPU and everything is fine, i'm gonna use this solution for now, it's not that bad since LOTRO do not require a lot of power.

Anyway, thank you for the detailed explanation, i understand better how it works now.

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