From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: Kirkwood PCI(e) write performance and DMA engine support for copy_{to,from}_user?
Date: Mon, 6 Sep 2010 15:03:47 +0100 [thread overview]
Message-ID: <20100906140347.GA24522@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20100906100244.GA6897@debian-wegner1.datadisplay.de>
On Mon, Sep 06, 2010 at 12:02:44PM +0200, Wolfgang Wegner wrote:
> Mapping the PCI memory space via mmap() resulted in some
> disappointing ~6.5 MBytes/second. I tried to modify page
> protection to pgprot_writecombine or pgprot_cached, but while
> this did reproducably change performance, it was only in
> some sub-percentage range. I am not sure if I understand
> correctly how other framebuffers handle this, but it seems
> the "raw" mmapped write performance is not cared about too
> much or maybe not that bad with most x86 chip sets?
> However, the idea left over after some trying and looking
> around is to use the DMA engine to speed up write() (and
> also read(), but this is not so important) system calls
> instead of using mmap.
Framebuffer applications such as Xorg/Qt do not use read/write calls
to access their buffers because that will be painfully slow.
next prev parent reply other threads:[~2010-09-06 14:03 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-06 10:02 Kirkwood PCI(e) write performance and DMA engine support for copy_{to,from}_user? Wolfgang Wegner
2010-09-06 13:46 ` Kirkwood PCI(e) write performance and DMA engine support for copy_{to, from}_user? saeed bishara
2010-09-06 13:58 ` Kirkwood PCI(e) write performance and DMA engine support for copy_{to,from}_user? Wolfgang Wegner
2010-09-06 14:03 ` Russell King - ARM Linux [this message]
2010-09-06 14:11 ` Wolfgang Wegner
2010-09-06 14:14 ` Wolfgang Wegner
2010-09-07 7:58 ` Kirkwood PCI(e) write performance and DMA engine support for copy_{to, from}_user? saeed bishara
2010-09-07 9:52 ` saeed bishara
2010-09-07 16:11 ` Wolfgang Wegner
2010-09-07 19:14 ` Nicolas Pitre
2010-09-08 8:35 ` Wolfgang Wegner
2010-09-09 16:21 ` Wolfgang Wegner
2010-09-13 17:10 ` Leon Woestenberg
2010-09-14 7:03 ` Wolfgang Wegner
2010-09-15 23:39 ` Leon Woestenberg
2010-09-07 18:38 ` Nicolas Pitre
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