![]() ![]() In Ubuntu 12.04 and 14.04, metacity's compositing-manager was false by default. In 16.04, it's been set to true. ![]() Metacity offers Screen Composition while being friendly on resources. To enable Compositing Manager of Metacity type in the following command. Gconftool-2 --toggle /apps/metacity/general/compositing_manager. Now you have compositing manager enabled. Reusing this command will disable the. How to enable composition for Lxde? You can a very basic compositing manager in the form of xcompmgr just make it auto start when you log in. Gnome-Do Docky: A New Dock On The Block. You will have to turn on the metacity compositing manager. Activate Gnome Do. Activate gnome composite effects. Gconftool-2 -s '/apps/metacity/general/compositing_manager' --type bool true. Deactivate gnome composite effects. ![]() ![]() I tried to pinpoint the advantages vs the disadvantages of that, and currently I've only seen disadvantages. I was testing with: gsettings set org.gnome.metacity compositing-manager false (or metacity --no-composite) versus: gsettings set org.gnome.metacity compositing-manager true (or metacity --composite) Speed: the speed for window drawing and moving around is 3-5 times slower when compositing is enabled. This is rather visible locally on old computers, but it becomes a real problem when Xorg is used over the network, like for example in LTSP thin clients. There, dragging around a window draws it in slow motion a whole lot behind the mouse, like a trail, while with compositing disabled, everything is lightning fast. RAM: xrestop shows that with a couple of windows open, metacity now needs 10 MB more RAM. This value increases with the number of open windows. Vsync: in most cases vsync was broken with or without compositing (while with compiz it's working much better). I tried with youtube videos, with VLC etc. The only difference I saw is that with some SDL games like teeworlds, vsync was working with compositing disabled, and was broken with compositing enabled. So my personal results is that metacity's compositing- manager= true doesn't have any advantage currently, and that it makes old client and LTSP client performance a whole lot worse. And unfortunately those are exactly the cases where we prefer gnome-session- flashback instead of e.g. Therefore I'd like to ask you to consider disabling it by default like it was in the past. I don't consider metacity as window manager for old pc and/or as being designed for usage over network. You can always disable compositing-manager if you need. Compositing manager is needed for invisible borders. Disabling it you have old problem - 1px area to resize windows vs. 10px currently. Disabling something does not help fixing problems. Open upstream bugs, put some testing info / data. Compare performance for example with compton (with xrender backend). So if you want that something changes / improves - open bugs. @Alberts, I'll do some more tests and come up with hard numbers concerning the performance of metacity with or without compositing. I do believe that in some cases it will be possible to optimize the performance through appropriate bug reports and patches; but I also strongly believe that there will be other cases where the different design choices (compositing) will come with an unavoidable performance hit. And while e.g. '3 times slower' may be acceptable in new e.g. Core i5 systems, it's not acceptable in new e.g. Atom systems. It doesn't affect only old PCs or networked X, it's just that it's more visible there. @Dmitry and Alberts, what if LTSP users find it necessary to have compositing off by default? (as a local setting in their installations) What issues should they expect from gnome-flashback then? - Harder window resizing due to 1 px border. - Notify-osd notifications ==> I did a quick test and they seem to work; albeit without transparency. Did I miss something? - Decorations ==> Example? I couldn't reproduce it. - Various docks ==> Example? And more significant, how much support should they expect from gnome-flashback developers for the non-compositing case? For example, your support in all the bug reports that I've filed so far was excellent! Does that mean that you won't be willing to do any non-compositing related work at all? Would you be willing to guide persons that are interested in working on such issues? Or to accept patches from them? I understand that gnome-flashback isn't specifically targeting old or networked clients, but does that also mean that it doesn't care at all about that use case? If that's the verdict, then maybe LTSP should evaluate other desktop environments like Mate as the default (I think 'marco' defaults to non-compositing in 16.04). No matter the answer(s), I again want to thank you very much guys for all your work!:). On Mon, Apr 4, 2016 at 5:49 PM, Alkis Georgopoulos > wrote: > @Alberts, I'll do some more tests and come up with hard numbers concerning > the performance of metacity with or without compositing. I do believe that > in some cases it will be possible to optimize the performance through > appropriate bug reports and patches; but I also strongly believe that there > will be other cases where the different design choices (compositing) will > come with an unavoidable performance hit. > If you have problems with compositing manager - turn it off, where is problem? And while e.g. '3 times slower' may be acceptable in new e.g. Core i5 > systems, it's not acceptable in new e.g. Atom systems. It doesn't affect > only old PCs or networked X, it's just that it's more visible there. > What is atom systems? Anyway @Dmitry and Alberts, what if LTSP users find it necessary to have > compositing off by default? (as a local setting in their installations) > If one day we will get per-session gsettings overrides then we could provide for example GNOME-Flashback (LTSP) and for this session install override file to disable compositing- manager. Currently good idea might be to provide script that configures user account for LTSP. > What issues should they expect from gnome-flashback then? > - Harder window resizing due to 1 px border. > This of course depends on theme. > - Notify-osd notifications ==> I did a quick test and they seem to work; > albeit without transparency. Did I miss something? > - Decorations ==> Example? I couldn't reproduce it. > - Various docks ==> Example? > > And more significant, how much support should they expect from > gnome-flashback developers for the non-compositing case? For example, your > support in all the bug reports that I've filed so far was excellent! > I mostly only test non-compositing only to make sure that I did not break something. From upstream point I am not interested. For example: upstream nautilus does not draw background anymore, it has transparent window. No compositor means - no desktop window or it will be black - you will never see background. As upstream developer I am interested that GNOME-Flashback is as close as possible to what I have upstream. And currently it is far from it (GNOME- Flashback: Unity). Does that mean that you won't be willing to do any non-compositing related > work at all? > No, if I get bug reports and I will know how to fix them than I will do it, but it will not be my priority. Would you be willing to guide persons that are interested in working on > such issues? Or to accept patches from them? I understand that gnome-flashback isn't specifically targeting old or > networked clients, but does that also mean that it doesn't care at all > about that use case? > If I would not care then I would probably remove option to disable compositing- manager. If that's the verdict, then maybe LTSP should evaluate other desktop > environments like Mate as the default (I think 'marco' defaults to > non-compositing in 16.04). > You are free to choose whatever that works for you best. No matter the answer(s), I again want to thank you very. @Alkis: > What issues should they expect from gnome-flashback then? > - Harder window resizing due to 1 px border. > - Notify-osd notifications ==> I did a quick test and they seem to work; albeit without transparency. Did I miss something? Right, without transparency and without rounded corners, which is not the best possible look > - Decorations ==> Example? I couldn't reproduce it. By decorations I meant the 1px border area, which you already mentioned. There may be problems with rounded corners here too. > - Various docks ==> Example? Almost any dock will have complicated (i.e. Not rectangular) geometry, which isn't supported without compositing. Try Plank for an example. @Alberts: > What is atom systems? Anyway Intel Atom? > As upstream developer I am interested that GNOME-Flashback is as close as possible to what I have upstream. And currently it is far from it (GNOME- Flashback: Unity). My plan is to fix this in Xenial+1. Less patches will mean less work for me, too:P. @Alberts, Dmitry: > No compositor means - no desktop window or it will be black - you will never see background. > My plan is to fix this in Xenial+1. Less patches will mean less work for me, too:P That's a good example, does that mean that in Ubuntu 16.10 if one doesn't use compositing he won't be seeing the desktop icons and background? @Alberts, which distro are you using or which one is closest with upstream flashback? Do you have numbers about usage? I have somewhat exact numbers for Greece: (less than half of the installations are shown in that map) 1000+ schools are using LTSP. They have on average one computer lab with 13 computers, serving 100 students. So 1000 installations, 13,000 computers, 100,000 users are using gnome-flashback 12.04 here. We didn't upgrade to 14.04 because of issues with the keyboard layout and the indicator. We'll upgrade them to 16.04 sometime this summer. They don't show up in the official stats much (popcon, ubuntu repository hits etc) because there's only one installation per school, the rest of the computers are netbooted from a single image. Worldwide I don't have exact numbers, the LTSP map is at but I suspect there are 10 times more installations, but only half of them with gnome-flashback. > @Alberts, Dmitry: > > No compositor means - no desktop window or it will be black - you will > never see background. > > My plan is to fix this in Xenial+1. Less patches will mean less work for > me, too:P > > That's a good example, does that mean that in Ubuntu 16.10 if one > doesn't use compositing he won't be seeing the desktop icons and > background? > No, it depends if ubuntu will still revert that nautilus change. Upstream nautilus does not draw background since 3.8: Desktop icons will be available, but without compositor background under icons will be black. @Alberts, which distro are you using or which one is closest with > upstream flashback? > I use Ubuntu (development version), but I am building full GNOME + GNOME-Flashback with JHBuild. I don't use Debian, but it should be good - it is not modified there. > @Alberts, I'll do some more tests and come up with hard numbers concerning the performance of metacity with or without compositing. I did some benchmarks and reported them in Now I'm more convinced that metacity's compositing-manager should be false by default. For LTSP users, I'll document how to create a /usr/local/ bin/metacity wrapper that launches `metacity --no-composite`. Quoting my conclusions from that bug report: I really think that the user's choices would be: 1) compiz, for every PC that supports it, 2) metacity --no-composite, for any PC that doesn't support compiz and that isn't able to spare 50%-80% of their FPS, 3) metacity --composite, ONLY for the minority of the PCs with graphics cards that can't run compiz and with so awesome CPUs that can spare 50-80% of their FPS. If you can find an example of such a PC, please let me know, currently I don't know of any. I do know of thousands of examples in category (2) though. Since `metacity --composite` is so much slower, affecting all apps and actions from simple drawing to scrolling to moving around windows to watching videos to game playing etc, I'd like to again ask you to consider NOT making (3) the preferred session for gnome-flashback for 16.04. Gnome-flashback -compiz could be the default (proposed one), and gnome-flashback -metacity the non composited version, with the --composite option only available as a gsetting for the minority of the people that would need it. The idea of having two different sessions (with and without compositing) sounds nice. Alberts, do you think this is something that could be done upstream? We'll need to clone the desktop and session files). Compiz is *not* a replacement for Metacity's compositing mode. Actually Compiz is very broken with GNOME Flashback: there is no Alt+right click to open panel preferences, there are issues with window decorations, etc. Actually I was even thinking of disabling Compiz session for Xenial because of these issues. On Wed, Apr 6, 2016 at 11:30 PM, Dmitry Shachnev wrote: > The idea of having two different sessions (with and without compositing) > sounds nice. Alberts, do you think this is something that could be done > upstream? We'll need to clone the desktop and session files). > Just because metacity --compostite vs. Metacity --no-composite? He wrote: > For LTSP users, I'll document how to create a > /usr/local/ bin/metacity wrapper that launches `metacity --no-composite`. > Probably way easier is to document, to execute in terminal: gsettings set org.gnome.metacity compositing-manager false I don't want even tell that non-composited case is supported. There is no transparency - we can not have background + nautilus desktop window. It looks broken and there is no easy fix. And sooner or latter ubuntu will stop patching background back in nautilus. Compiz is *not* a replacement for Metacity's compositing mode. Actually > Compiz is very broken with GNOME Flashback: there is no Alt+right click > to open panel preferences, there are issues with window decorations, > etc. Actually I was even thinking of disabling Compiz session for Xenial > because of these issues. > I hope that compiz will get support for _GTK_FRAME_EXTENTS, then there will be no issues with window decorations. Alt+right click? Super+Alt+right click. Anyway I do not plan to drop compiz session at least yet. Otherwise why I did bother replacing libmetacity-private with libmetacity? > Probably way easier is to document, to execute in terminal: > gsettings set org.gnome.metacity compositing-manager false It's easy for one sysadmin to run a few commands in a terminal. It's not easy for hundreds of students, e.g. 5-10 years old, to run a few commands in a terminal. Sysadmins (or packagers) can provide a system-wide override with /usr/share/ glib-2. 0/schemas/ 20_metacity. Override but that will only work with new users. They can provide overrides for all users with mandatory gsettings. But the /usr/local/ bin/metacity wrapper can have logic to active or deactivate compositing per user, or per machine, based on the CPU, the graphics card etc etc, and it's very easy to integrate it with LTSP. Anyway that part isn't important; the most important thing is if the non-compositing case will be a supported use case in Ubuntu gnome-flashback 16.04 or not. I'll do some more benchmarks with gnome-flashback and with other DEs like Mate/XFCE/LXDE. Thank you guys!
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