Re: Xinerama infrastructure

On Tue, Feb 17, 2004 at 02:02:54AM +0000, Steve Salazar wrote:
> > > Ok, sorry.  Like I said I don't know X except as a user so I'll 
> >summarize
> > > from that point of view and not even try to use any X jargon:
> > >
> > > 1. When I use XFree on one head, it is fast
> > > 2. When I use XFree on two heads, it is really slow
> > > 3. When I use Xig on two heads, it is fast
> >
> >just to satisfy my curiosity, on what hardware is this?
> >
> P4 2.2GHz, 512MB RAM, Matrox G450, Fedora Core 1.

That's almost identical configuration to mine (except that my CPU
is significantly slower than yours).  I also suffered this problem
with a single head G400 and PCI 2 Millenium 2's - Given mike's comments
about it's performance on other graphics cards, and the mga multihead
performance on other platforms, i suspect that this is in fact a 
mga+xfree specific issue.

I was never successful in having enough system resources to get xfree to
compile on this box, so I can't look at this problem right now, but once 
fd.o's x plays a little nicer with my desktop configuration, I'll have a 
look at it and see if it's still a problem, and if it is, see if I can't
do something about it (disclaimer: no promises of actual action, either
expressed or implied :)

I will throw out the obversvation that the performance issues are not nearly
as clear cut as they would seem - I really need to do some actual objective
testing before I can comment on exactly what is up, however.  The performance
drop, btw, does seem to be far more than bus bashing, although I am sure that
also plays a part - we're talking an order of magnatide of difference in 
performance here, not just the 2x-4x that you'd get due to blitting out the 
extra pixels.  Also, it's often in small windows that it occours - the context
menu in KDE takes an age to redraw, for example, on my system, as do anim
gifs in any browser, but yet vice runs at 50fps constantly!  Like I said, in
order to actually fully understand this, I need to do some actual obejctive
testing on it, which I don't have time for this week, particularly since it'd
require building xfree.  (Homage to another thread: fuck imake!))

As a side note, did you try the matrox binary g450 drivers?  I've heard
reports that performance on those is significantly improved, but since
I only have g400s myself, I can't verify this.  (Again, I wish I could
afford Xig's rather large prices for multihead configs :)

	-- jj

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