From: Lonsn <lonsn2005@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: lonsn@163.com
Subject: mmap performance of reserved top sdram in powerpc platform
Date: Thu, 28 Jan 2010 22:47:31 +0800 [thread overview]
Message-ID: <6caf4b5a1001280647p49984279g7cd034d824182c80@mail.gmail.com> (raw)
Hi all:
I have reserved top 128MBytes sdram for PCI DMA usage. External PCI
master sends data to top sdram and then wake up user space app.
User space use /dev/mem and mmap to access this region and then send
them to network using socket.
I found send speed of memory data in /dev/mem to network is very slow.
(300Mbits/s)
If I malloc memory data in user space and then send to network, the
speed is much higher. (750Mbits/s).
I know the reason is the sdram in /dev/mem marked as un-cached.
How can I set the top sdram as cached to impove performance and be
sure that the data is coherent.
My kernel version is DENX-v2.6.32.
Thanks.
reply other threads:[~2010-01-28 14:47 UTC|newest]
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