intel driver gets slow as soon as I rotate on a 1920x1200 display
jbarnes at virtuousgeek.org
Thu Jul 26 14:27:43 PDT 2007
On Thursday, July 26, 2007 1:46 pm Thomas Glanzmann wrote:
> could someone explain to me what "tiling" is? So that I can at least
> follow this conversation. ;-)
Tiling refers to the way graphics memory is organized in memory. In a
linear configuration for example, each pixel in the scanout buffer
(what you see on the screen), starting at the origin, is placed in
increasing memory addresses, with the "pitch" being the width of your
screen (e.g. 1280 pixels times the number of bytes per pixel) in bytes.
In a tiled configuration, memory is organized into tiles, 4k in size for
example (matching the system page size), each with its own small pitch.
Continuing the example above, the whole scanout buffer would be
composed of such tiles and subject to a few extra constraints (e.g. the
total pitch of the screen has to be a multiple of the tile pitch,
etc.). Organizing things this way allows the graphics chip to more
easily cache spatially local data, and also improves the way memory is
accessed for spatially local operations, improving performance and
reducing power consumption.
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