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? Is the output/input port on a seperate device function? Or is it just a specific MMIO BAR in your PCI device? > 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-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
