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Comment by akdev1l | Hacker News Reader

>These extreme gains are the result of benching against vanilla without fsync, which is what anyone gaming on linux uses

Not for anyone using a kernel without these patches. Which would be most people.

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Unless you are running an ancient LTS distribution, you at least have fsync. But then also recognize, with the ancient LTS distribution not carrying any enhancements for the last few years, your drivers are also out of date and games will play terribly for unrelated reasons.

"Have fsync" is not a sufficient requirement. You need a kernel with windows-compatible fsync patches, and many distributions do not ship those.

Most people? What mainstream Linux distros ship without fsync or esync support?

Well I can tell you that if it didn’t make it upstream Fedora didn’t ship it.

It looks there was a copr for a custom kernel-fsync and projects like Bazzite or Nobara are adding patches.

From my understanding the fsync patches were never upstreamed.

The common gaming-focused Wine/Proton builds can also use esync (eventfd-based synchronization). IIRC, it doesn't need a patched kernel.

The point being that these massive speed gains will probably not be seen by most people as you suggest, because most Linux gamers already have access to either esync or fsync.

Maybe you are right about esync but anyway I would also gather a lot of people don’t have that either. At least personally I don’t bother with custom proton builds or whatever so if Valve didn’t enable that on their build then I don’t have it.

> if Valve didn’t enable that on their build then I don’t have it.

The Proton build is Valve's build. It supports both fsync and esync, the latter of which does not require a kernel patch. If you're gaming on Linux with Steam, you're probably already using it.

https://github.com/ValveSoftware/Proton/?tab=readme-ov-file#...

I thought you meant Proton-GE or such other patched builds of proton.

I would assume most of them? I'd be surprised if distros like Debian, Ubuntu, Fedora, etc. would ship non-mainline kernel features like that.

Sure, gaming-focused distros, or distros like Arch or Gentoo might (optionally or otherwise), but mainstream? Probably not.

Of course, esync doesn't require kernel patches, so I imagine that was more broadly out there. But it sounds like fsync got you performance pretty close to what ntsync can do, but esync was quite a bit behind both? With vanilla being quite a bit behind esync?

(Also, jeez, fsync, what a terrible name. fsync is a syscall that has to do with filesystem data. So confusing.)

esync and fsync both use mainline kernel features.

Last I checked, every distro of note had its own patchset that included stuff outside the vanilla kernel tree. Did that change? I admit I haven't looked at any of that in... oh, 15 years or so.

Depends on the distro.

Fedora looks like it carries a whooping 2 patches on top of upstream

> I would assume most of them? I'd be surprised if distros like Debian, Ubuntu, Fedora, etc. would ship non-mainline kernel features like that.

It's best not to assume with these things. With my stock Debian Stable kernel, Proton says this:

fsync: up and running.

And when I disable fsync, it says this:

esync: up and running.

> But it sounds like fsync got you performance pretty close to what ntsync can do, but esync was quite a bit behind both?

No, esync and fsync trade blows in performance. Here are some measurements taken by Kron4ek, who maintains somewhat widely used Wine/Proton builds:

https://web.archive.org/web/20250315200334/https://flightles...

https://web.archive.org/web/20250315200424/https://flightles...

https://web.archive.org/web/20250315200419/https://flightles...

> With vanilla being quite a bit behind esync?

Yes, vanilla Wine has historically fallen behind all of them, of course.

> Also, jeez, fsync, what a terrible name. fsync is a syscall that has to do with filesystem data. So confusing.

We can agree on this. :)

The article says fsync uses futexes which are a completely standard kernel feature.

If you read more carefully it says fsync needs some enhancements to the futex API, called futex2. The original patch that fsync needed called the syscall futex_wait_multiple. Eventually futex2 made it into the mainline kernel, but the syscall is called futex_waitv. Not sure if the wine fsync implementation was updated to support the mainline kernel futex2 implementation.

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