> > I did some benchmarks, and my framebuffer is *way* faster when writing
> > than when reading:
> That is quite normal.
Unfortunately, at least X and few framebuffer modes can not survive
that too well.
vesafb ypan mode attempts to do video-to-video copy, which is slow.
Xserver attempts that, too.
> > That is 6 times slower! This is also very visible in X, where moving
> > regions is expensive, while just drawing regions is fast. For example
> > gnome-terminal is *way* faster *with* transparent background option.
> > Any idea why such assymetry? [This is toshiba 4030cdt with vesafb and
> > 2.4.5]
> Writes to a PCI device can be queued or posted. Reads from a PCI device for
> obvious reasons have to stall the CPU until the data returns.
But they can't be posted indifinitely, right? I'm copying whole
framebuffer at a time, I do not believe PCI has enough buffers to
cache *that*. [Or is it using some kind of burst mode it can not use
for reading? That does not give a sense, you can cache reads, too....]
-- The best software in life is free (not shareware)! Pavel GCM d? s-: !g p?:+ au- a--@ w+ v- C++@ UL+++ L++ N++ E++ W--- M- Y- R+ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to email@example.com More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/