On Wed, Jan 4, 2012 at 4:33 AM, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote: > On Wed, Dec 07, 2011 at 10:16:40PM +0800, ustc.mail wrote: >> Dear all, >> >> In NIC driver, to eliminate the overhead of dma_map_single() for DMA >> packet data, we have statically allocated huge DMA memory buffer ring >> at once instead of calling dma_map_single() per packet. Considering >> to further reduce the copy overhead between different NIC(port) ring >> while forwarding, one packet from a input NIC(port) will be >> transferred to output NIC(port) with no any copy action. >> >> To satisfy this requirement, the packet memory should be mapped into >> input port and unmapped when leaving input port, then mapped into >> output port and unmapped later. >> >> Whether it's legal to map the same DMA memory into input and output >> port simultaneously? If it's not, then the zero-copy for packet >> forwarding is not feasible? >> > > Did you ever a get a response about this? No. > > Is the output/input port on a seperate device function? Or is it > just a specific MMIO BAR in your PCI device? > Platform: x86, intel nehalem 8Core NUMA, linux 2.6.39, 10G 82599NIC(two ports per NIC card); Function: Forwarding packets between different ports. Targets: Forwarding packets with Zero-Overhead, despite other obstacles. --Yanfei >> Hope PCI expert to post your suggestion. >> >> Thanks! >> >> --Yanfei >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-pci" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-arch" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
