Re: [Linux-fbdev-devel] Re: FBdev updates.

[Antonino Daplas <adaplas@pol.net>]

On Fri, 2003-02-21 at 03:58, James Simmons wrote:
> 
> > I was for five weeks in U.S., so I did not do anything with
> > matroxfb during that time. I plan to use fillrect and copyrect
> > from generic code 
> 
> I have ported the accelerated functions to the new api. What is left is to 
> deal with the loadfont and putcs issue which I'm working on the code right 
> now.
> 
> > (although it means unnecessary multiply on
> > generic side, and division in matroxfb, 
> 
> ????
> 
> > but well, if we gave
> > up on reasonable speed for fbdev long ago...). 
> 
> This is not true. Several benchmarks have shown a large performance 
> improvement in 2.5.X.
> 

2.5.x might be a bit slower with bpp8 but at higher color depths is
significantly faster. And this is done with a single generic color
exapnd function that replaces the entire fbcon-cfb*.c in 2.4.  And it
will theoretically still draw correctly whatever the condition is (any
bpp from  1-32,  unaligned origin, pitch, width, etc). 

Drivers with accelerated color expansion, if done correctly, _should_
perform better whatever the color depth.  

However, using fonts with widths not divisible by 8 will be several
folds slower.  This should be helped if we add some form of tile/texture
blitting support to fbdev.

Note: I cannot test with 12x22 fonts in 2.4 because some/most drivers do
not support it.

Tony

no accel
scrollmode: yredraw
font: 8x16
visual: packed pixels

time cat /usr/src/linux/MAINTAINERS

linux-2.4.20

bpp8
----
real    0m2.499s
user    0m0.000s
sys     0m2.500s

bpp16
-----
real    0m8.324s
user    0m0.000s
sys     0m8.320s

bpp24
-----
real    0m12.364s
user    0m0.000s
sys     0m12.370s

bpp32
-----
real    0m16.274s
user    0m0.000s
sys     0m16.280s

linux-2.5.62

bpp8
----
real    0m2.557s
user    0m0.003s
sys     0m2.553s

bpp16
-----
real    0m4.051s
user    0m0.002s
sys     0m4.050s

bpp24
-----
real    0m9.520s
user    0m0.000s
sys     0m9.520s

bpp32
-----
real    0m7.496s
user    0m0.002s
sys     0m7.494s