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  • #21
    Originally posted by planetguy View Post
    Now that Wayland has pointer lock and XWayland has XWarpPointer emulation, SteamOS Chemist could move to Wayland by default and throw their weight behind XWayland for X11 game compatibility.
    Wayland is even worse than X11, since the forced VSync even in fullscreen applications means everything has at least one additional frame of latency. In their infinite wisdom, the Wayland people also do not intend for anyone to ever be able to turn off VSync, because that would go against their vision.

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    • #22
      Originally posted by efikkan View Post
      Speaking of low latency, I wonder why SteamOS is not using a "low latency" kernel? It should be a no-brainer to get a more fluid experience.

      Anyway, those "universal" game engines are too bloated in terms of latency.
      Because the graphics subsystem doesn't use any real-time kernel functionality IIRC, so why you're even bringing this up is beyond me.
      Real-time kernels are used by audio systems such as Jack.

      And usually, general-purpose game engines aren't too bad with input latency. The problem almost always lies with drivers and hardware.

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      • #23
        Originally posted by Wind0zB3st View Post
        Wayland is even worse than X11, since the forced VSync even in fullscreen applications means everything has at least one additional frame of latency. In their infinite wisdom, the Wayland people also do not intend for anyone to ever be able to turn off VSync, because that would go against their vision.
        wat? On KDE I can disable it with a compositor option from the KDE settings.

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        • #24
          IMO, if Valve were really serious about SteamOS they would had created they own Linux/SteamOS from scratch where they would have full control of each single package on it (at least on package repositories), and not made it based (depending) on something - wherever it be. And/Later, make available some kind of contender for other distributions.

          Following this way they would make things more easy for game developers, and allow better hardware integration for also for whom sell prebuilt steam machines. People whom eventually are whiling to have SteamOS just for gaming do not care to have bleeding edge version of libraries on the system.

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          • #25
            Originally posted by alexcortes View Post
            IMO, if Valve were really serious about SteamOS they would had created they own Linux/SteamOS from scratch where they would have full control of each single package on it (at least on package repositories), and not made it based (depending) on something - wherever it be. And/Later, make available some kind of contender for other distributions.

            Following this way they would make things more easy for game developers, and allow better hardware integration for also for whom sell prebuilt steam machines. People whom eventually are whiling to have SteamOS just for gaming do not care to have bleeding edge version of libraries on the system.
            They have already full control of any package on it. It's not like they are using a vanilla Debian that updates on its own. They add the stuff they need to it, like for example a fully blobbed kernel with NVIDIA and AMD drivers and their own optimizations.

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            • #26
              Originally posted by efikkan View Post
              Speaking of low latency, I wonder why SteamOS is not using a "low latency" kernel? It should be a no-brainer to get a more fluid experience.

              Anyway, those "universal" game engines are too bloated in terms of latency.
              The same reason they based their distro off of debain. Because their not in the OS business. They are game makers. I am surprised they had the time to implement the custom compositor on top of it. What would be interesting is if someone wrote a light weight and modular wayland based DE. Like no cruft from previous DE's based on X. It would be interesting swapping out say a controller based or keyboard based input on demand for the entire UI with libinput .

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              • #27
                Originally posted by Wind0zB3st View Post

                Wayland is even worse than X11, since the forced VSync even in fullscreen applications means everything has at least one additional frame of latency.
                No, it doesn't mean that. ​​​​The kernel KMS subsystem only requires providing the next buffer to be displayed before the vertical blank period [0]. The total latency will be higher than that depending on the specific Wayland compositor and client, but can definitely be less than one frame from when the display hardware starts scanning out the new buffer.

                [0] With changes by yours truly ​​​​which just landed for 4.9, it can even work if the new buffer is provided only during the vertical blank period, but it depends on the specific timing/driver/hardware and requires the compositor to use new ioctl flags.

                In their infinite wisdom, the Wayland people also do not intend for anyone to ever be able to turn off VSync, because that would go against their vision.
                I suspect tearing is a no-go for VR anyway, so I can't see any problem with that specifically.

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                • #28
                  Michael
                  New article about this tweet?


                  This is huge!

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                  • #29
                    Originally posted by Wind0zB3st View Post
                    Because the graphics subsystem doesn't use any real-time kernel functionality IIRC, so why you're even bringing this up is beyond me.
                    Real-time kernels are used by audio systems such as Jack.
                    The low latency kernel provided in Ubuntu and others is not a real realtime kernel, but rather a tuned generic kernel with a scheduler running at a higher frequency causing reduction in scheduling latency and synchronization.

                    Using a low latency kernel will pretty much eliminate "micro stutter", which is small variations in frame rate which usually don't affect the average performance. A typical application rendering will have small fluctuations, e.g. every 2nd to 5th frame or so will be slightly delayed. At 60 Hz small variations of 1-2 ms is very noticable to some people, and the variations can be even larger. Switching to a low latency kernel will reduce such fluctuations down to <0.1 ms, generating a much more fluid stream of frames.

                    So this doesn't matter much to end-to-end latency, but have a great impact on stutter.

                    Originally posted by Wind0zB3st View Post
                    And usually, general-purpose game engines aren't too bad with input latency. The problem almost always lies with drivers and hardware.
                    Actually not, latency in games and simluators usually consists of the following:
                    1) Hardware input: mice, keyboards, etc. Range: <1 ms for PS/2, ~30 ms for Bluetooth...
                    2) OS overhead, scheduling, etc. 0.1 - 10 ms or more
                    3) Game engine - logic. At 60 Hz 16.7 - 33.3 ms
                    4) Game engine - rendering. At 60 Hz 16.7 ms (Driver latency and OS latency will have an impact here)
                    5) Vsync (optional) At 60 Hz 16.7 ms
                    6) Screen input latency: ~1 - 30 ms
                    The end-to-end latency of a typical game is ~100 ms, and even more for games played over a network.

                    I don't know what kind of problems you are thinking about in hardware, except for 1 and 6, everything else is more or less software.

                    Originally posted by notanoob View Post
                    The same reason they based their distro off of debain. Because their not in the OS business. They are game makers.
                    The packages already exist, they don't have to invent anything.

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                    • #30
                      That poor Lian Li case. They're very nice cases, but the anodized aluminum panels scratch easily. Very poor case for carrying around, naked. A cheap steel case would've been far better, even if a bit heavier.

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