So you’re trying to build a DVD player using Debian Jessie and an Atom D2700 on a Poulsbo board, and you’ve even biked down to the used DVD warehouse and picked up a few $3 90’s classics for test materials. Here’s what will happen next:
- Gnome 3 at 1920×1080. The interface is sluggish even on static graphics. Video is right out, since the graphics is unaccelerated, so every pixel has to be pushed around by the CPU.
- Reduce mode to 1280×720 (half the pixels to push), and try VLC in Gnome 3. Playback is totally choppy. Sigh. Not really surprising, since Gnome is running in composited mode via OpenGL commands, which are then being faked on the low-power CPU using llvmpipe. God only knows how many times each pixels is getting copied. top shows half the CPU time is spent inside the gnome-shell process.
- Switch to XFCE. Now VLC runs, and nothing else is stealing CPU time. Still VLC runs out of CPU when expanded to full screen. top shows it using 330% of CPU time, which is pretty impressive for a dual-core system.
- Switch to Gnome-mplayer, because someone says it’s faster. Aspect is initially wrong; switch to “x11” output mode to fix it. Video playback finally runs smooth, even at full screen. OK, there’s a little bit of tearing, but just pretend that it’s 1999. top shows … wait for it … 67% CPU utilization, or about one fifth of VLC’s. (Less, actually, since at that usage VLC was dropping frames.) Too bad Gnome-mplayer is buggy as heck: buttons like “pause” and “stop” do nothing, and the rest of the user interface is a crapshoot at best.
On a system like this, efficiency makes a big difference. Now if only we could get efficiency and functionality together…