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.
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