A question about "Software rendering for gnome-shell"

[Michal Jaegermann]

On Tue, Feb 21, 2012 at 05:12:13PM -0500, Adam Jackson wrote:
> On Tue, 2012-02-21 at 13:10 -0700, Michal Jaegermann wrote:
> 
> > Running 'LIBGL_ALWAYS_SOFTWARE=1 gnome-shell --replace', as proposed by
> > drago01, indeed starts an intended mode gnome session, both before and
> > after installing these scratch packages, but results are spectacularly
> > useless. 'gnome-shells' eats whatever CPU it can get so one can look at
> > results but no hope of doing anything useful.
> 
> CPU usage is going to be higher.  That's what "software rendering"
> means.  I've not found it onerous on an early c2d, but again, I really
> need to know what kind of CPU is being complained about.

This particular one is a 64-bit (albeit quite old) processor:

vendor_id	: AuthenticAMD
cpu family	: 15
model		: 5
model name	: AMD Opteron(tm) Processor 142
stepping	: 1
cpu MHz		: 1600.062
cache size	: 1024 KB

on a board with 2GB of a physical memory.  I know some machines around,
and doing useful job, where this is a quite powerhouse in a comparison.
When forced with LIBGL_ALWAYS_SOFTWARE=1 gnome shell was taking all the
time between 94% and 96% of CPU and a response latency for a keystroke
or a mouse movement was in a order of few seconds.  My guess is that
more of CPU would be grabbed if only it would be available.  At the
first moment I thought that the whole thing just locked up and only
after some delay I realized that I was mistaken.

I have no idea how much this CPU usage would have to be reduced before
this setup would pass a "laugh test" but probably 10% for gnome-shell
would be way too much.

  Michal