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. :)
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.)