From: "Etienne Lorrain" <etienne_lorrain@yahoo.fr>
To: linux-kernel@vger.kernel.org
Subject: Re: specific optimizations for unaccelerated framebuffers
Date: Thu, 4 Oct 2001 14:31:18 +0200 (CEST) [thread overview]
Message-ID: <20011004123118.49603.qmail@web11806.mail.yahoo.com> (raw)
In-Reply-To: <3BBC4A4E.AC6106A6@ftel.co.uk>
--- Paul [private mail] wrote:
> You might like to do some performance measurements on
> X with a shadow framebuffer - see
>
> http://www.xfree86.org/4.1.0/apm5.html
This seems to still use the processor to copy the shadow buffer
to the video memory, you will still have the PCI write stall...
> I have a machine with an SiS 630 where the video memory _is_
> main memory - the impact of the graphics processor continually
> DMAing data for display is huge.
I am not speaking of DMA'ing at the refresh frequency (approx 70 times
per second the complete video memory), just the modified 64Kb blocks,
"once upon a while": if a single pixel is written twice, you will just
see the latter written value on the screen - but who cares.
Been able to DMA the complete video memory image around 5-10 times/second
should be over the human eye sensitivity.
Moreover this pixel will stay on the processor memory cache a lot
longer, even without MTRR processors.
Etienne.
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next parent reply other threads:[~2001-10-04 12:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3BBC4A4E.AC6106A6@ftel.co.uk>
2001-10-04 12:31 ` Etienne Lorrain [this message]
2001-10-04 14:01 ` specific optimizations for unaccelerated framebuffers Christopher Friesen
2001-10-04 14:28 ` Etienne Lorrain
2001-10-04 22:59 ` Alex Bligh - linux-kernel
2001-10-06 0:35 ` Pavel Machek
2001-10-15 9:26 ` Etienne Lorrain
2001-10-04 8:58 Etienne Lorrain
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