Re: gEDA-user: PCB+GL Testers (please test)

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Thu, 2010-11-04 at 23:37 +0000, Richard Barlow wrote:
> On Thu, 2010-11-04 at 16:43 +0100, Kai-Martin Knaak wrote:
> > I tried Richards power too and got the same result as Peter: No more than 11 
> > FPS, even with my new ATI card driven by the closed source fglrx. :-|
> > Just like my own board, there is no much divfference compared to the before 
> > pours branch.
> > What makes his set-up faster by an order of magnitude?
> 
> Perhaps I'm doing something wrong? To get those numbers I've been
> opening the board using the freshly compiled PCB, running the
> 'benchmark' command (Type ':' then 'benchmark') and reading the values
> printed to stdout. If this is wrong then I apologise for the incorrect
> readings.

Sounds ok, although unless you're screen is a fast refresh CRT, you are
rendering higher than the vsync frequency of the monitor. That is a clue
that you don't have sync to vblank set.

Not to say that is wrong.. but for some cards, sync to vblank is a
default, so people will never see higher than about 60Hz (for an LCD).

Due to the way sync to vblank works, it does give slightly lower
performance even on my system when I'm getting 10-20fps. The page flips
are synchronised to vblank events, so there might be some dead-time in
the rendering.

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)



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