AMD Enabling FreeSync Video Mode By Default With Linux 5.18, Merging AMDKFD CRIU

[shmerl]

So how do you use that? Do video players like mpv need some special support for it? What about video in Firefox?

[shmerl]

Freesync is already enabled in KDE... or this is different?

It's for video playback if I understood correctly. Most video players were blacklisted for adaptive sync until now.

For example I see this in /usr/share/drirc.d/00-mesa-defaults.conf:

<application name="mpv" executable="mpv">
  <option name="adaptive_sync" value="false" />
</application>

See a ton more programs blacklisted there.

I'm not sure how that is handled in conjunction with what amdgpu is doing.

[Quackdoc]

I'm not sure I like the idea of FreeSync enabled by default. I might be in a minority, but I have a FreeSync monitor (which I didn't buy because of FreeSync), but I prefer to use regular Vsync (I like to have steady 60 fps and I reduce the input lag with framerate limiters in most of my games anyway). About 4 years ago I tried FreeSync on Windows out of curiosity and the experience wasn't good. It caused constant stutters every few seconds and didn't really reduce input lag. I also accidentally turned off my monitor while in game, so after I turned it back on, the image was frozen and I couldn't do anything but a hard reboot.
So yeah, FreeSync didn't leave a very good taste in my mouth. Will there be a kernel argument to turn it off?

freesync does nothing for input lag... I have a feeling you probably set something up wrong.

[shmerl]

freesync does nothing for input lag... I have a feeling you probably set something up wrong.

Why not? It should help reducing input lag as long as your framerate is below max monitor refresh rate (i.e. in range of the adaptive sync). If it's above, to reduce input lag you need to prevent vsync (i.e. allow tearing).

Input lag happens when there is some delay between starting to display available frame and when the frame is actually available (which can be the case in vsync scenario). Tearing reduces that, and syncing refresh rate to current framerate obviously reduces that too.

[Quackdoc]

Why not? It should help reducing input lag as long as your framerate is below max monitor refresh rate (i.e. in range of the adaptive sync). If it's above, to reduce input lag you need to prevent vsync (i.e. allow tearing).

Input lag happens when there is some delay between starting to display available frame and when the frame is actually available (which can be the case in vsync scenario). Tearing reduces that, and syncing refresh rate to current framerate obviously reduces that too.

the only thing freesync does is sync monitor refresh rate with display rate. it is not vsync, nor is it a framerate limiting tool the user themsleves needs to do whatever to keep the refresh rate withing freesync range. enabling freesync, will not enable vsync (though some games may do so themselves I suppose) nor will it limit your FPS. in fact people erroniously enabling freesync without vsync is actually a fairly large issue. or at least was at one point.

the way it was said made it sound like to me none of these steps were taken. freesync does nothing unless additional steps are taken. and even with those steps taken, freesync would not contribute to a reduction in input lag (unless you consider screen tearing)

I tried FreeSync on Windows out of curiosity and the experience wasn't good. It caused constant stutters every few seconds and didn't really reduce input lag.

[shmerl]

the only thing freesync does is sync monitor refresh rate with display rate

Which reduces any potential latency between readiness of the frame and it's appearance on the screen, meaning it reduces input lag.

Obviously it only works when current framerate is within monitor's adaptive sync range. When it's above, as I said, to reduce input lag you need to simply allow tearing there.

So within the range - adaptive sync. Above the range - tearing. That's the best experience you get for minimizing latency.

[Jabberwocky]

This is 6 years and 332 days after initial Windows support. I am not trolling or sarcastic. I'm actually glad, Here's why...

I have been playing competitive online games in a Windows VM for ~8 years. Having low-overhead low-latency vsync in Linux has not bothered me much personally.

That said, AMD and Linux should celebrate the only open implementation that it's good enough to be set to default.

This was a massive codebase that was rejected multiple times IIRC. Honestly, well done for not giving up.

The amount of work that was done to finish this project is probably beyond my comprehension.

[Quackdoc]

Which reduces any potential latency between readiness of the frame and it's appearance on the screen, meaning it reduces input lag.

Obviously it only works when current framerate is within monitor's adaptive sync range. When it's above, as I said, to reduce input lag you need to simply allow tearing there.

So within the range - adaptive sync. Above the range - tearing. That's the best experience you get for minimizing latency.

even then freesync doesn't really lower input lag. as the frames are still displayed when they are ready (unless the monitor does something funky). which is why I said, unless you considering screen tearing to be a part of input lag, which sure, there is an argument for and against it.

but yeah, my entire point was I don't think he setup freesync right, which could have caused some of the issues he was experiencing. freesync sure is nice though. don't think I could live without it lol

[shmerl]

even then freesync doesn't really lower input lag. as the frames are still displayed when they are ready

Lag by definition means not displaying it when they are ready with some delay for "reasons". One of those reasons in the classic (no adaptive sync / VRR) setup is vsync. If you display it right away, it means that delay is avoided, so less input lag.

[aufkrawall]

So within the range - adaptive sync. Above the range - tearing. That's the best experience you get for minimizing latency.

No need to accept the ugly transition and tearing when fps would go beyond VRR range, just prevent vsync lag by using an fps limiter on top.