[haiku-bugs] Re: [Haiku] #5383: MTRR regression: AGP transfer inconsistencies
- From: "bonefish" <trac@xxxxxxxxxxxx>
- Date: Thu, 18 Feb 2010 14:15:39 -0000
#5383: MTRR regression: AGP transfer inconsistencies
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Reporter: rudolfc | Owner: bonefish
Type: bug | Status: in-progress
Priority: normal | Milestone: R1
Component: - General | Version: R1/Development
Keywords: | Blockedby:
Platform: All | Blocking:
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Changes (by bonefish):
* blockedby: 5353 =>
Comment:
Replying to [comment:7 rudolfc]:
> The driver's buffer is used for writing by the CPU only. The GPU reads
from this buffer.
> Using MTRR-WC has a big-time acceleration performance increase compared
to write-trough or uncached (especially in accelerated 3D, I benchmarked
this once).
I was a bit surprised that WT is slower than WC, since the specification
for WT says that "write-combining is allowed". Setting the frame buffer to
WT instead of WC makes the graphics feel tremendously slower, so
apparently the "is allowed" part doesn't mean it's actually done.
Anyway, the problem should be fixed for P6 and later in r35515, since
overlapping ranges are now handled correctly. Please close the ticket, if
you can verify this.
--
Ticket URL: <http://dev.haiku-os.org/ticket/5383#comment:8>
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