richardgv
commented
11 years ago Update: Does compton --vsync opengl under XRender backend works?
Well, it probably is something that could be fixed in compton, but none of us are professionals in the field of core X and OpenGL implementation and hardware, that makes the problem tricky to fix. I myself almost always use a desktop computer and has never cared about power usage.
You are not first one who noticed the issue. p4ddy, which used to stay on our IRC channel (FreeNode/#compton), reported the same thing once, but he indicated that upgrading the kernel and driver helped a lot. Not applicable for an Arch user with bleeding-edge packages, though.
Usually, compton paints a lot, more than all your applications combined (except when you have a 3D game), because it paints everything your application paints for another time and occasionally other areas (e.g. wallpaper, shadow), as well. And a compositor processes typically much more events than an application. Thus you may consider a compositor inherently expensive. The X architecture, formed in 1980s, contributes a lot of the overhead, though, and Wayland/Mir may be direction of the future.
I did a number of tests with powertop on compton, xcompmgr, and cairo-compmgr, and found compton generally causes a significant higher amount of GFX wakeups (200% - 300%), but less "usage", especially GLX backend. It might has something to do with our attempts to minimize painting which involves synchronous communication with X that fragmented compton's usage on resources, and porting to XCB may be helpful. (But we can't. People are using compton on very old systems where XCB probably doesn't exist yet.) I lost patience when I found high statistical variance on the results I got, somehow.
I believe 2D and 3D are basically equivalently handled on modern graphic systems, so the 3D mode thing is most likely non-existent.
Some advices, although I truly doubt if they would help much: compton has some options that may have either positive or negative effects on the wakeups: --glx-no-stencil, --glx-swap-method, --glx-no-rebind-pixmap, --paint-on-overlay, --vsync (try other VSync methods). --glx-use-copysubbuffermesa may break VSync, and --glx-copy-from-front generally performs poorly on open-source drivers. Lift some options you don't need (e.g. shadow, background blur), if you think it's going to help. Tuning your driver options and playing with its VSync may give you something interesting.
If (and only if) you have a lot of spare time, comparing the results of using different options of compton, and other compositors, tracing which part of compton is causing the wakeups (e.g. by commenting out certain code), tracing which commit is introducing high wakeups (by building old versions compton), tracing under what kind of workload compton works the poorest and best, etc., probably will lead to the correct answer of the question. Try to build a reliable test environment and use longer and repeated tests to get rid of statistical variance, and don't forget to look at the X process. I will do some tests here when I have time, but I believe it depends on the driver a lot, and I don't have a laptop.
pschyska
AGenchev
mutcianm
Hey,
first of all, thanks for compton. It was the only solution to me tearing problems so far :smile:
I'm using arch linux on a Lenovo X230 with ivybridge integrated intel graphics chip. I don't use a DE but i3wm on plain Xorg. This setup gives me heavy tearing, i.e. when scrolling vim buffers. TearFree with sna acceleration OTOH leads to laggy display/skipped frames.
Compton with glx backend and vsync opengl-swc works like a charm. I don't have tearing and the display is smooth.
However I noticed in powertop an increase of power drain of about 1-2W (going up to 11W from 9W in my test). The intel chip's power saving time is about 20% (RC6/RC6p/RC6pp depending on my module setting - the percentage stays the same for all settings). With XRender backend or no compton I get about 80-90% RC6 with heavy tearing though.
Is there some setting I could try to save some power?
I wondered if the chip is set to "3D-mode" when using the glx backend and that's why I can't sleep properly. BTW, this test is with a terminator instance in fullscreen and powertop open. Powertop itself will only refresh display every 10s or so, but I use a blinking cursor. Also the i3bar refreshes every 5s.
If this is not something that can be fixed in compton, just close this issue. I will use it regardless :+1:
Thanks Paul