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Benchmarking The Ubuntu "Low-Jitter" Linux Kernel

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  • Paradox Ethereal
    replied
    And maybe that is the most important thing you can learn from this entire thread. Lowlatency/lowjitter is going to happen regardless. I just do it early.

    Peace Be With You.
    Last edited by Paradox Ethereal; 10-27-2017, 06:35 PM.

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  • Paradox Ethereal
    replied
    edit: outdated.
    Last edited by Paradox Ethereal; 10-27-2017, 06:34 PM.

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  • Paradox Ethereal
    replied
    edit: outdated links.
    Last edited by Paradox Ethereal; 10-27-2017, 06:34 PM.

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  • liam
    replied
    Originally posted by Paradox Uncreated View Post
    Where the hell does these idiots come from. A whole tread with explanations, and sane thinking. And yet they don`t understand? Go and complain to Intel who makes the CPUs I like." reduce latency from low microseconds to tens of nanosecond "

    Finally I have have my transparent os, with 0.2ms max jitter. If that doesn't appeal to you, instant sound, accurate FPS, low latency internet, well then. You should buy some kind of framereducer. I mean seeing how much ignorance there is online, it will probably be a big hit. Finally you can get those 5 choppy frames. Some kind of LCD feature, so ofcourse the "throughput" still goes on behind.

    What a bunch of perplexingly stupid loosers. Anyway I am having a good time, and thought I'd share it. But ofcourse there are those who serve the firespirit satan, and denounce all that is good.

    Peace Be With You.
    I love the substantive responses of four year olds.
    I truly hope you are a troll and not the zealot you seem to be (seriously, "Peace Be With You" and yet you make the most disgusting statements preceding it...I'd imagine God would be pissed, if not for hypocrisy but at least blatant inconsistency).
    Ugh, mixing OS discussions with religious imagery (and seeming statements about morality).

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  • Paradox Ethereal
    replied
    Finally I have have my transparent os, with 0.2ms max jitter. If that doesn't appeal to you, instant sound, accurate FPS, low latency internet, well then..
    ??

    Peace Be With You.
    Last edited by Paradox Ethereal; 10-27-2017, 06:33 PM.

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  • liam
    replied
    Originally posted by Paradox Uncreated View Post
    Why is gamer2k posting in this thread? To be an example of how much babble can be done, that is not according to simple observation? "It spends time calculating preemption". LOL. The benchmarking even shows some higher numbers, and no other are below 1fps difference. What you do OBSERVE though, is a game that was choppy (low GRAPHICS throughput) to one that runs smoothly at 72fps. HIGHER throughput, when using preemption with graphics. Again, we do not care about theoretical numbers, that say nothing about what is ACTUALLY happening on screen, relating to USER experience. I really hate people who are that far removed from reality.

    Peace Be With You.

    I'm sorry, but you are just wrong.
    Michael benchmarks throughput fine and your kernel didn't perform any of these miracles you're talking about. We've seen his numbers, and they confirm what we know from theory: low latency doesn't increase throughput (in this context, FPS).
    You can have a choppy game but still high throughput (since it is an average). For simple scenes, and low kernel contention, you might generate a hundred frames in less than a second but other times when there is more gpu kernel communication, or more kernel contention, you might only manage 20 fps. So, over long periods that can average out to high fps but extreme jitter.
    Does that not make sense to you?

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  • liam
    replied
    Originally posted by Paradox Uncreated View Post
    Sidicas is on the right track. Later poster is completely wrong.

    Indeed it should be easy to understand, that if kernel blocks for 5ms, rather than 0.2ms, timing jitter is going to be present, and alter framejitter, and also 5ms lost of 20ms, to calculate frame.

    Peace Be With You.
    Assuming I am the "later poster" could you please tell me how I am completely wrong?
    It could be a language issue but I don't understand how you fail to grasp that RT adds overhead. Yes, less jitter (i.e. smoother frame rates), but you also lose the ability to run for periods of uninterrupted time on the cpu, which is sometimes necessary in order for a frame to be completed. Now, I could see a setup where you prioritized frame completion and delivery (that is, it responds to the irqs from the gpu before almost anything else) over everything else but that would mean, necessarily, that you'd have a less responsive system since inputs would then be delayed. That kinda defeats the point.
    Setting up a RT machine requires a lot of thought.

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  • Paradox Ethereal
    replied
    Yeah max 2 frames render ahead.

    edit xorg.conf (gksu gedit /etc/X11/xorg.conf), and add under Section “Device”

    Option “RegistryDwords” “OGL_MaxFramesAllowed=0?2; PowerMizerEnable=0?0; PerfLevelSrc=0?2222;”

    Only the maxframes if you want powermizerstuff.

    Peace Be With You.

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  • Sidicas
    replied
    Originally posted by gamerk2 View Post
    More often then not, you get periods where you miss that interval, leading to the previous frame being displayed a second time. Worst case, during the following interval, two frames are created, and the first will be dropped. So your frame output looks something like this:

    1) Frame #1
    2) Frame #1
    3) Frame #3 (frame 2 was created, but frame 3 was also created before the screen was ready for a new image, and is thus dropped)

    Then people wonder why they get 60FPS when running a SLI config, but the game is laggy. THAT is a latency problem, and something that needs a much more serious look in the future. (Techreport did a VERY good analysis on this not too long ago, fyi)

    It's actually worse than that.
    The proprietary drivers for both AMD and nVidia will not drop frame #2 by default since it would hurt the "smoothness" of the game.

    Rather they will give that to the display instead of frame #3 even though frame#3 is ready.
    Frame #3 goes into a waiting area called the triple buffer where it will sit and wait to be displayed on the next refresh cycle. By the time the display finishes with frame #3 and gets to the next refresh cycle, it would hope that frame#4 would be ready by then or you're going to get another frame#3.

    The proprietary drivers also have a little "feature" built into them that they will pre-render up to about 4 frames before letting the GPU idle.. Which means you could have up to 4 of the most recent frames sitting in your triple buffer waiting for the screen to refresh and each refresh the user is getting the oldest frame presented to them.. The reason for this is that the drivers expect the game to suddenly stop feeding the graphics card frames. Due to the OS wandering off and doing other things or whatever, I kind of like to think of it as MS Windows having ADD. That way the graphics card has a nice cache of frames that it can present to the user even when it suddenly stops getting frames to process for a prolonged period. Just so it has something to show to the user rather than the same frame. Of course, this does horrible horrible things to the responsiveness of the game, but both AMD and nVidia like to enable it by default because it adds "smoothness" to the video (having lower amounts of difference between frames). It's just another example on the pile of how responsiveness in games isn't being respected as it should be.

    Both pre-rendered frames and triple-buffer can typically be disabled in Catalyst control center / nvidia control center. It will help responsiveness, but the game will not be as pretty or fluid.
    Last edited by Sidicas; 10-23-2012, 04:31 PM.

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  • Paradox Ethereal
    replied
    Edit: Link unavable.
    Last edited by Paradox Ethereal; 10-27-2017, 06:32 PM.

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