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KWin Now Supports Suspended Compositing

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  • #31
    Originally posted by BlackStar View Post
    On the contrary, basic desktop usability is greatly increased through the use of compositing. Shadows, overlays, window thumbnails, all help you navigate faster.
    Or you can use a tiling WM and not need to navigate, because everything is there in front of you all the time.

    /begin religious war over WMs

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    • #32
      I couldn't tell from the article, but if I'm running a windowed OpenGL application like say Doom 3 or OilRush would it disable compositing for me? I really prefer to not play games fullscreen especially on Linux.
      Since I have two screens, I've had too many problems where fullscreen games would stretch across both screens, so I'm always using windowed mode.

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      • #33
        Originally posted by mrugiero View Post
        Several reasons:
        1. You might not have a good GPU.
        2. You might not WANT a good GPU, if you use the computer just for work.
        In that case KWin does not activate compositing anyway.

        Originally posted by mrugiero View Post
        3. You might have a good GPU, but really "don't give a fuck" if you can see a shadow, a transparency or FX.
        So? Compositing and desktop effects are two completely different things. Nobody is forced to enable effects in KWin when compositing is enabled.

        Originally posted by mrugiero View Post
        Maybe you want it to be as fast as it can be, and you don't want compositor to take resources.
        WTF? Do you have any proof that KWin with compositing takes more resources than KWin without it?
        If anything, the system should run smoother and (in case of mobile devices) require less battery because the CPU renders less.

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        • #34
          Originally posted by deanjo View Post
          Because for the most part it is useless and serves no practical purpose.
          Lower CPU utilization and with it lower battery draining is a real benefit of compositing (no effects need to be active).

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          • #35
            Originally posted by Awesomeness View Post
            Lower CPU utilization and with it lower battery draining is a real benefit of compositing (no effects need to be active).
            GPU takes power as well. Feel free to post the links to the benchmarks showing compositing extending battery life.

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            • #36
              If the GPU still has 2d parts, it can likely shut down 3d parts when compositing is off.

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              • #37
                Originally posted by BlackStar View Post
                Shadows expose window relationships (active window, child windows). I find this singularly important - the non-composited gnome 2 desktop looks flat out confusing to my eyes.

                Overlays are important for things such as pop-up notifications. Do you recall how e.g. volume notifications used to look when running fullscreen apps or videos on non-composited desktops? (Extreme flickering and slowdowns everywhere). They also improve things such as window resizing (have you seen the new touch-aware resize overlay in Ubuntu/Unity?)

                Unfortunately, composition has acquired a bad reputation due to buggy drivers and an initial focus on bling rather than usability. This is unfortunate, since a modern desktop isn't conceivable without a compositor.
                First, I don't need to recall about it, I use openbox without compositor (basically, xcompmgr is too buggy, and my driver is too useless to be used with any other compositor). But that point is more about responsiveness than desktop navigation (in fact, if I'm using fullscreen video I'm actually not using the desktop itself).
                And, as much as I value that feature, I can not take advantage of it because I have no touchscreen (also, I don't use Unity :P), and that's my point after all: not everyone should want to use compositing. Anyway, I'm not sure if the GUI wich will be taken from KWin is the one wich makes one able to disactivate the compositor permanently (I mean, to not use it) or the one to dynamically disable it. If it is the second, my point goes nowhere, because noone is telling "you shall use composite" :P

                About the last two points, I agree that most of the bad fame of compositing is really buggy drivers and compositors, and bad priorities in the implementation, as I said before. But it's still not true the dependency on compositors to have a "modern" desktop for everyone, due to not being just one use.

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                • #38
                  Originally posted by pvtcupcakes View Post
                  I couldn't tell from the article, but if I'm running a windowed OpenGL application like say Doom 3 or OilRush would it disable compositing for me? I really prefer to not play games fullscreen especially on Linux.
                  Since I have two screens, I've had too many problems where fullscreen games would stretch across both screens, so I'm always using windowed mode.
                  I don't remember completely, but in another thread (one about wayland) someone said he use a different X server for each screen, that might help you with that problem.
                  But you probably would not move windows from a screen to another...

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                  • #39
                    Originally posted by Awesomeness View Post
                    In that case KWin does not activate compositing anyway.


                    So? Compositing and desktop effects are two completely different things. Nobody is forced to enable effects in KWin when compositing is enabled.


                    WTF? Do you have any proof that KWin with compositing takes more resources than KWin without it?
                    If anything, the system should run smoother and (in case of mobile devices) require less battery because the CPU renders less.
                    I wasn't talking about the specific KWin case, but in general. In fact, I can't care less about what the devs do with KWin, as far as I don't use KDE.
                    As someone said, the GPU uses power too. Also, the tech itself is more resources consuming (not necessarily from the CPU), because it uses different buffers for the windows, and operates with them independently if they are in front.
                    Also, the effects itself are not the biggest problem, yes they are more operations, but the main problem I see is the GPU or even the CPU (KWin probably uses only if it can use the GPU, but, as I said, I'm talking in general, and for example xcompmgr can work just with CPU) has to work with all the windows, independently if they are background (it might not be a problem with two or three windows, though).

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                    • #40
                      Originally posted by mrugiero View Post
                      I wasn't talking about the specific KWin case, but in general. In fact, I can't care less about what the devs do with KWin, as far as I don't use KDE.
                      As someone said, the GPU uses power too. Also, the tech itself is more resources consuming (not necessarily from the CPU), because it uses different buffers for the windows, and operates with them independently if they are in front.
                      Also, the effects itself are not the biggest problem, yes they are more operations, but the main problem I see is the GPU or even the CPU (KWin probably uses only if it can use the GPU, but, as I said, I'm talking in general, and for example xcompmgr can work just with CPU) has to work with all the windows, independently if they are background (it might not be a problem with two or three windows, though).
                      Things are not nearly as clear-cut as you make them. By working with each window independently, the compositor can reduce CPU usage when moving windows around. Without a compositor, you need to repaint each window as it is gradually uncovered. With a compositor, you can simply blit the persisted window contents to the backbuffer.

                      Originally posted by randomizer
                      Or you can use a tiling WM and not need to navigate, because everything is there in front of you all the time.

                      /begin religious war over WMs
                      I have tried this but it tiling just didn't appeal to me. The window layout tended to be suboptimal until I corrected it manually. If I have to move windows manually, I might as well do away with the tiling manager completely.

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                      • #41
                        Originally posted by BlackStar View Post
                        Things are not nearly as clear-cut as you make them. By working with each window independently, the compositor can reduce CPU usage when moving windows around. Without a compositor, you need to repaint each window as it is gradually uncovered. With a compositor, you can simply blit the persisted window contents to the backbuffer.



                        I have tried this but it tiling just didn't appeal to me. The window layout tended to be suboptimal until I corrected it manually. If I have to move windows manually, I might as well do away with the tiling manager completely.
                        That's a good point, I didn't thought about that. However, I'm not trying to show how "OMG! Compositing is EVIL!", my post is primarily an answer to the guy who said something like "Why anyone would not want compositing". And my point to that respect, is still correct. There are several reasons, the main reason is about not being commanded to use it, is freedom. If compositing works awful for you because your GPU's driver is shitty, the fact it is not fault of the compositor's programmers does not change the fact that it does not work OK.
                        If I have a computer which works OK with compositing, I usually use it, in fact, in the machine I'm right now I use XFCE with compositing enabled. The way I use it, it is just for the eye-candy. Some people showed me practical reasons to use it here. The problem is when someone suppose that everyone should use the things they use.

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                        • #42
                          Originally posted by mrugiero View Post
                          The problem is when someone suppose that everyone should use the things they use.
                          Exactly! I'm using composition now because it works with recent drivers. When it didn't work, I didn't use it. But it's easier for me to move windows from one desktop to another in desktop grid or to pick a window from a expose effect. On the other hand, some people prefer just using one desktop, some people use one window per desktop, some people use one terminal per desktop (1337 ), but that is personal preference. And I always liked KDE because it has always been configurable and it has always given you choice whether you want to use desktop effects or not, whether or not you want to use single or double click to open files etc. GNOME never had such a configurability as KDE has. People that like GNOME say that this is simple. Maybe it is for them, but it certainly isn't for me. I usually don't use desktop's defaults and like to have the ability to easy configure my desktop as I wish. KDE provides that for me, other desktops don't. Some other people like defaults, some like to configure its desktops via configuration scripts - as I said: it's a personal preference. \end{religious war over WMs/DMs}
                          That's why I was initially shocked when I saw Martin's comment that manually changing states will not be needed in KDE SC 4.8. It will always be needed. Removing this would be one step back, one step to the same direction GNOME 3 is going (no offenses ), and I would be very sad about that because I used KDE for a long time and I still today think that KDE 3.5 rocks better than 4.6 but nevertheless I use KDE 4.6 (being on Arch I'm kind a forced to use newest packages, but I don't mind).

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                          • #43
                            Originally posted by elanthis View Post
                            And you think that's even technically possible why, exactly?

                            X11 doesn't have a "full screen" mode. Apps just set their window size accordingly. It's pretty hokey.

                            The only thing the WM/compositor can really tell is whether an application has a fullscreen, top-level, on-top window or not. Whether that app happens to be a game or a LibreOffice slideshow or a web browser, the WM has no freaking clue.

                            That is in part why the KWin folks mentioned a NETWM addition for apps to signal whether they want "maximum performance" full screen. That would then finally allow apps to give the WM enough information to make those kinds of intelligent decisions.

                            Since that protocol does not yet exist, at all, it means that apps will need to be updated.

                            And that's what happens when you design a half-ass system without thinking things through from the start and relying on "evolving the API over time, hey it's Open Source, we can just update _every damn app in the world_ to comply with the update!"
                            another solution: let the user decide.

                            its my freaking computer and am the user, so i should know better which apps i want "maximum performance" full screen.

                            a simple option or gui for this so i can whitelist the app i want should be enough

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                            • #44
                              Originally posted by Awesomeness View Post
                              Lower CPU utilization and with it lower battery draining is a real benefit of compositing (no effects need to be active).
                              I have yet to see lower CPU usage with composite enabled nor have I seen better battery life. Even so it doesn't apply to me as 95% of the time I am on a desktop. For me, personally, a laptop is to confining and limited in capabilities so battery life is for the most part non applicable here.

                              But I would love to see links that back up your claim.

                              Comment


                              • #45
                                Originally posted by randomizer View Post
                                Or you can use a tiling WM and not need to navigate, because everything is there in front of you all the time.

                                /begin religious war over WMs
                                WTF? KWin supports tiling!
                                Telling KWin users to use a tiling window manager or to get in “war” with you is like telling Christians to believe in Jesus Christ.

                                Originally posted by locovaca View Post
                                GPU takes power as well.
                                But less power. It's a well known fact and also the reason GPU-based video decoding is mandatory on pretty much any mobile device because decoding a 720p video on a CPU also drains power beyond belief.

                                But hey, if you think you alone know better than the entire industry of mobile devices, be my guest and post benchmarks for your claim.

                                Originally posted by locovaca View Post
                                Feel free to post the links to the benchmarks showing compositing extending battery life.
                                Read Martin’s blog post, for example. He also thinks that disabling compositing is not helping battery life.
                                Or you can try it yourself: Move a window around fast. On my aging laptop moving my almost fullscreen Firefox window around fast Xorg hogs the CPU with ~40% and the fan kicks in after a minute or so.
                                With compositing (despite transparency effects, shadows and such) the CPU utilization of Xorg stays low. It's at ~15% on its peak. No fan kicks in (so no overheating GPU and heat is energy which comes from the battery).

                                Originally posted by mrugiero View Post
                                I wasn't talking about the specific KWin case, but in general.
                                This thread is not about compositing in general. It's about KWin specifically.
                                So again: It makes no sense to completely disable KWin’s composite support if the GPU hardware is capable enough. If the GPU is too weak, KWin doesn't enable compositing automatically anyway. And for fullscreen OpenGL games – and this is what this news item is about – KWin will disable compositing automatically for pretty much the only use case compositing affects performance.
                                But for plain desktop use with a GPU younger than 6 years: Enabled compositing offers no drawbacks – only benefits.

                                Originally posted by mrugiero View Post
                                In fact, I can't care less about what the devs do with KWin, as far as I don't use KDE.
                                This is a thread about a KWin news item. Leave if you are not interested in KWin.

                                Originally posted by madjr View Post
                                another solution: let the user decide.
                                its my freaking computer and am the user, so i should know better which apps i want "maximum performance" full screen.
                                a simple option or gui for this so i can whitelist the app i want should be enough
                                You should read the comments in Martin’s blog post. He wrote that it'll be possible to set a window rule to override the automatic composite suspension.

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