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Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

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Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#211

Post by sph »

Aardwolf wrote: post #179
NelsonMinar wrote: post #15

One thing that's lovely about Linux is this kind of analysis is not only possible, but meaningful. These results will get reported back to the graphics software authors and the distribution packagers and the ecosystem will improve. There's no sense with Microsoft that kind of improvement is possible. I recently switched to Linux after years on Windows desktop, mostly because the KDE Plasma desktop feels snappier than…

> One thing that's lovely about Linux is this kind of analysis is not only possible, but meaningful. If only they'd actually DO something with this meaningfulness. I love and use Linux as my daily driver, but desktop environments and everything around it have become so complicated yet worse than before. In the past a simple config file with intuitive setting names inside of them could make you do anything you wanted.…

My bet is that either you’re using a Mickey Mouse distro, or you tweaked your themes/thrashed your config and now you have all those issues that I haven’t seen in a decade since installing custom GTK themes.

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#212

Post by xbar »

horsawlarway wrote: post #123
jandrese wrote: post #98

Earlier quoted context omitted.

The context here is the article's author is a twitchy FPS player, those extra 3ms are something that community agonizes over. I appreciated how much effort was put into controlling the variables in this test. There's a whole lot of witchcraft associated with these kinds of efforts and he sat down and did the measurements and got real numbers. My hat is off to OP.

ping is going to dominate over 3ms in pretty much every situation. And the non-xwayland numbers are all within a single ms of each other. --- Not to undermine the measurements of the author (agree with you, it's a cool effort), but my read is that this was basically proof that it doesn't matter.

Since 4ms is already about at the limit of my input latency tolerance for snappiness, I came to a different conclusion: "Wayland VRR" is the only tolerable Wayland option.

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#213

Post by ChocolateGod »

pelorat wrote: post #114
wing-_-nuts wrote: post #57

Earlier quoted context omitted.

>give Bazzite a whirl I never really understood Bazzite's immutable fs thing. Can one install standard dev stuff (i.e. compilers, ides, etc) easily under bazzite? This use case is the main reason why I lean towards maybe using cachyos

Yes of course, but you need to do it via the package manager. You can't "sudo make install". If you build your own software and want to install it system wide, you need to flatpack/brew it or run it in a docker container. (obviously you can modify the filesystem if you really really really want to). Bazzite is gaming oriented version of Fedora CoreOs. There are many different versions. I am running bluefin. I've trie…

> You can't "sudo make install"

You can if you're going to target /usr/local, which should be where make install installs if it's following the FHS correctly.

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#214

Post by ChocolateGod »

NelsonMinar wrote: post #74
wing-_-nuts wrote: post #57

Earlier quoted context omitted.

>give Bazzite a whirl I never really understood Bazzite's immutable fs thing. Can one install standard dev stuff (i.e. compilers, ides, etc) easily under bazzite? This use case is the main reason why I lean towards maybe using cachyos

Bazzite mostly suggests installing stuff via Flatpak or Homebrew. (No, really, brew on Linux lol). You can also layer in things with rpm-ostree but it's clunky. I think the immutable OS makes sense for a consumer but not for a developer. So I'm using Nobara instead. It's a different Fedora-for-gaming but has most of the same improvements. It is a traditional system, not immutable. CachyOS is also very popular and tha…

> but not for a developer

I disagree. Immutable distros are great for developers, you set your dev env up in a container environment and when it goes pear shape you can just tear it down and start again without needing to worry about leaving a mess on your host OS.

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#216

Post by superkuh »

hparadiz wrote: post #20
superkuh wrote: post #6

Earlier quoted context omitted.

You can't just test one wayland compositor and talk about the performance of all wayland compositors. They're vastly different, especially when it comes to the extensions to wayland needed to handle input devices (ref: https://wayland.app/protocols/ ). It's not like how xorg is the standard strong reference implementation for X11 everywhere that works the same everywhere. What's probably happening is that other wayla…

You will also get different results by gpu, compiler, kernel, architecture, and then of course compositor. Even a slightly different version of some lib might throw off the results. In any case the methodology in the post is sound and should be used for benchmarking in the future.

The methodology works and it's a fine result. But it's important to remember that talking about one wayland is not talking about all waylands the way talking about xorg/X11 is.

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#217

Post by MBCook »

Aurornis wrote: post #40
prhn wrote: post #11

Awesome article. I switched my daily driver / gaming rig to Fedora a few months back. Everything seems snappier compared to Windows, but not sure if it’s in my head, and I’ve been very curious about gaming input latency. This helps answer some questions. I recently switched to hyprland and I’m very interested how that fits in these results. hyprland uses Wayland so I hope the author might revisit now that hyprland is…

With the exception of XWayland, all of the tests had input latencies within a very small range. No human could tell them apart by those latency differences alone. I would be amazed if someone could notice the 3ms difference jump to XWayland. The difference could be much larger on a slower monitor. However the differences between Wayland and X11 as protocols is negligible. XWayland as an implementation looks to have a…

Also the author is testing a game engine.

It’s possible that Gnome/KDE/whatever has wildly different latencies on X11 vs Wayland.

I’d be interested in seeing that test.

But it’s great to know the difference is so small here, which is what I’d expect.

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#219

Post by magicalhippo »

lII1lIlI11ll wrote: post #205
slackfan wrote: post #134

Earlier quoted context omitted.

I can tell down to about a 3ms difference in lag. Actually even down to 1ms, it's not all its cracked up to be, lemme tell you.

You think you can and will inevitably fail to do it in blind testing.

While reaction response is around 100ms, for predictive movements, ie press a button exactly when a bouncing ball hits the ground, average people can get down into 5-7ms of timing accuracy[1]. Trained people can get below 4ms in certain cases.

Of course, the brain adapts. I played an online shooter at >100 FPS using my 144 Hz monitor (when that was the best). I visited a buddy who's PC could only muster 30-40 FPS, and he asked me to show me how I played, since he struggled.

I sucked so bad due to the extra input lag. Felt like my character was running in a pool of molasses. But after about 15-20 minutes my body adapted, and my performance started increasing and my hits started connecting more reliably. I got to about 90% of my regular performance after 30 or so minutes.

So while one could tell back to back, one could also compensate. But at some point the extra input lag will matter, and will get you killed or make you miss that shot. Hence why I could only get up to ~90% of my normal performance on my buddy's PC.

[1]: https://jov.arvojournals.org/article.aspx?articleid=2213289

Re: Measuring Input Latency on Linux: X11 vs. Wayland, VRR, and DXVK

#220

Post by magicalhippo »

mikenew wrote: post #90
Aurornis wrote: post #44

Earlier quoted context omitted.

> and noticed that significant lag Only xwayland showed that result. The difference was only a couple milliseconds. That’s in the range where I start to doubt that people are feeling the latency difference. If it was 10-20ms I could believe it, but not when it’s a couple milliseconds. The author of this post did a good job of getting all of the other confounding settings out of the way. It’s possible that the people…

Yeah at 120hz each frame is 8ms. So you're only missing a single frame around 30% of the time. I certainly want my latency as low as I can get it. But I'm pretty skeptical that anyone is truly feeling the difference of a couple ms.

This[1] study suggests image framerate does not significantly affect our ability to perform predicted moves accurately in time, above a certain minimum which is lower than 24 Hz.

Moving the mouse and then pressing a button, or pressing one key and then another, are both cases of predictive moves.

So it seems one shouldn't rely on framerate when talking about the limits of sensing input lag, at least in general.

[1]: https://jov.arvojournals.org/article.aspx?articleid=2213289

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