Re: [PATCH] Disable mach64 accelerator if stride is not multiple of 64

On Thu, 18 Jun 2009, krzysztof.h1@poczta.fm wrote:

quoted

Mikulas Patocka napisa³(a):


BTW. why doesn't it use accelerator for screen scrolling? It seems to 
redraw all non-empty characters, which is fast if most of the screen is 
empty but gets slower if the screen is full of text.

It uses the accelerater.. The screen redraw uses accelerated imageblit() function 
if it exists.
In order to use the blitter one must define FBINFO_READS_FAST flag. However,
it may not end up faster. It is faster if the memory is fast while chip is not
so fast relatively (e.g. all new GeForce and Radeon chips, 3DFxx Voodoo3+ have 
very fast memory attached).
It  may vary for other chips, i.e. even if your ati card equiped with sgram it is 
faster it may be slower for the same chip with sdram.

Also, if blitter is used for scrolling the crolling speed goes down with increasing 
pixel depth which is not a case for the redraw method.

Regards,
Krzysztof

I tried to define FBINFO_READS_FAST. At some tests it was as fast as 
without it, at some it was about 20% faster.

So the only way how to avoid this slow-scroll annoyance would be to batch 
the updates --- i.e. don't scroll after each line of output but scroll 
after for example 5 lines. But it would mean major code redesign...

Mikulas