On Mon, 18 Feb 2008 19:52:28 +0100
Andi Kleen <email@example.com> wrote:
they use a cached mapping and use clflush for the cases they want to be sure
the GPU sees the data. This turns out to be faster than WC.
(think "double to tripple digit percentage")
since then the graphics programming paradigm has changed as well;
WC is really bad for reading data no matter what; it focuses on group writes
so that you don't get one transaction per write, but reads are extremely slow.
And apparently in the current graphics systems (with "composite" and the like)
all of this stuff doesn't get used anymore. Instead they use cached mappings,
acceleration engines etc.
depends on which driver. The new generation Intel graphics ones don't.
I doubt the proprietary ones do either, those are even more performance tuned.
I understand that the radeon driver is doing or going to do something similar to the
Intel driver as well.
the X drivers need to do what is best; the ones with acceleration use WB nowadays.
(For the Intel driver that is somewhat recent, so it could be that your distro
doesn't do that yet).
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