On 16/7/07 10:23, "Alan Cox" <alan@xxxxxxxxxxxxxxxxxxx> wrote:
>> significant (though I assume WC would at best help a little, I'm considering
>> other approaches, too): Scrolling a 1280x1024x16 screen takes, on the test
>> system I'm primarily trying this out on, on the order of a second. This is
>
> A lot of work on this has been done in X by the X and Gnome developers
> including producing some routines which use the largest possible aligned
> loads to reduce the big cost (which is PCI reads). Having a write
> combining video memory can help (but some cards also put stuff like
> command queues there which X cannot WC).
Does this mean that defaulting to setting up WC on a power-of-two-sized
region starting at the framebuffer address is not really safe on a fair
number of systems?
 -- Keir
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