Re: [PATCH 2/3][FBCON]: New Scrolling Mode: YPAN + REDRAW

["Antonino A. Daplas" <adaplas@hotpop.com>]

On Tuesday 06 July 2004 15:38, Geert Uytterhoeven wrote:
> On Tue, 6 Jul 2004, Antonino A. Daplas wrote:
> > Added a new scrolling mode (SCROLL_PAN_REDRAW) to fbcon that should
> > greatly benefit unaccelerated drivers such as VESA fbdev.  An increase of
> > 3-10 times in scrolling speed can be expected.
>
> Nice!

Thanks.  Adding it was actually easy, all I have to do was reuse code already
present in fbcon.c.

>
> > Using an accelerated driver, we see almost the same effect but
> > not as dramatically:
> >
> > 1. SCROLL_MOVE - accel
> > real    0m3.112s
> > user    0m0.000s
> > sys     0m3.112s
> >
> > 2. SCROLL_REDRAW - accel
> > real    0m2.604s
> > user    0m0.000s
> > sys     0m2.603s
> >
> > Redraw is still faster than move, but not much.
>
> That probably depends on the card (imageblit vs copyarea)?
>

True.  I really don't want to speculate on this, it varies from 
hardware to hardware, driver to driver. The only thing I can
definitely say is that pan/wrap is the most effective means
to facilitate scrolling.  Whether it be combined with imageblit
or copyarea, I'll leave that up to the driver maintainers.

Tony




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