[dev] Lag in when changing view to a OpenGL window

From: Anders Straadt <anders_AT_straadt.dk>
Date: Thu, 3 Dec 2015 23:59:13 +0100


When using Mod-[1..n] to view a tag that exposes a window running
OpenGL I often experience a "random" lag, like a delay of 200-2000ms
before the window draws itself. At least I think it's related to
OpenGL because it happens in google-chrome and blender (blender.org),
but not in "simpler" applications like xterm, st, mupdf and geeqie. I
also wrote a minimal x11/glx program in C and tried timing different
calls - the delay always occurs in glClear() (the program doesn't do
anything else that draws the window).

It doesn't seem to matter if the window is floating, tiled or monocle,
or how big the window is. But a weird symptom is that at least for
google-chrome and blender it seems to matter how quickly I switch back
to the window... i.e. if I'm viewing blender, switch to another tag
and quickly switch back again, then it always lags. But if I'm viewing
blender, switch to another tag, wait a few seconds and then switch
back, then there's no lag. With my x11/glx program and other SDL2
programs I wrote, it always lag a bit. I don't know if it's because
these programs continuously draw 60 frames per second while
google-chrome and blender seems to only draw the window when something

It's the same both in builds of the official dwm-6.1 tarball and HEAD
from git.suckless.org, both with minimal patching
- and when testing with the tarball I didn't apply the
viewtoleft/right code)

I just migrated from Awesome (http://awesome.naquadah.org/) - it
doesn't happen there.
Received on Thu Dec 03 2015 - 23:59:13 CET

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