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RyanJGray / aliasIsolation

Anti-aliasing mod for Alien: Isolation
The Unlicense
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bug: Low performance with low GPU utilization #34

Open Ripthorn opened 1 month ago

Ripthorn commented 1 month ago

Describe the bug For some reason, performance tanks with low GPU utilization in this part of the game. When I first went through this area, I didn't notice any FPS drops. Without the mod, this same area runs without any issues.

How to reproduce just play up to this segment of the game

Expected behaviour Game running at 60fps

Screenshots [Video] https://1drv.ms/v/s!AlSgH9mVunleguYpe5BDbFoicTIiYg?e=QQkDYR

Setup details

RyanJGray commented 1 month ago

Hey!

Thanks for the report.

It's probably about time that this issue is tracked here.

This is something I've been trying to narrow down for some time, it seems like performance in certain larger (but also some smaller) areas of the game just tanks.

One level I use for testing is Severance Part 1, when you leave Ransome's apartment, turn right and enter into the lobby, the FPS tanks noticeably.

I am having a bit of trouble working out exactly what bit of the code is causing such a big performance hit even with a profiler, I suspect it's the shadow jitter/unjitter phase of the TAA implementation, as most of the matrix math is done on the CPU.

I have updated the graphics math library the mod uses to the latest version, with no noticeable improvement.

With such low GPU utilisation, it feels CPU related.

I'll look into this more and experiment with the shadow pass, and see if I can identify what needs fixed.

Ripthorn commented 2 weeks ago

Hey!

Thanks for the report.

It's probably about time that this issue is tracked here.

This is something I've been trying to narrow down for some time, it seems like performance in certain larger (but also some smaller) areas of the game just tanks.

One level I use for testing is Severance Part 1, when you leave Ransome's apartment, turn right and enter into the lobby, the FPS tanks noticeably.

I am having a bit of trouble working out exactly what bit of the code is causing such a big performance hit even with a profiler, I suspect it's the shadow jitter/unjitter phase of the TAA implementation, as most of the matrix math is done on the CPU.

I have updated the graphics math library the mod uses to the latest version, with no noticeable improvement.

With such low GPU utilisation, it feels CPU related.

I'll look into this more and experiment with the shadow pass, and see if I can identify what needs fixed.

Which GPU did you try with? I tested the same segment shown in the video today with an RTX 3060Ti and there was no performance loss.

RyanJGray commented 2 weeks ago

Strange, I'm using a laptop RTX 3080Ti, and I tend to see a relatively hefty performance loss in large spaces in-game.

Although. I am using Valve's Proton compat. layer as I use Linux, so it seems more that there's some inefficiencies with my particular setup when I talk about performance issues.

On my Steam Deck the performance is good, hitting a solid 60FPS in most locations, with a small drop during cutting torch use, to be expected I guess