Hi Thomas, On ven., févr. 17 2017, Thomas Petazzoni <thomas.petazz...@free-electrons.com> wrote:
> Does not make sense, because it's not the SW that refills the RX > descriptors with the address of the RX buffers. It's done by the HW. > > With HWBM, I believe you have no choice but to read the physical > address from the RX descriptor. But you can probably optimize things a > little bit by reading it only once, and then storing it into a > cacheable variable. > > So maybe: > > - For SWBM, use the strategy proposed by Jisheng > - For HWBM, at the beginning of the RX completion path, read once the > rx_desc->buf_phys_addr, and store it in rxq->buf_dma_addr[index] For the HWBM path storing rx_desc->buf_phys_addr in rxq->buf_dma_addr[index] is not useful as we only use it in a single function. But a quick improvement could be to use the phys_addr variable. Indeed we store the value of rx_desc->buf_phys_addr in it and we never used it, instead we always use rx_desc->buf_phys_addr. Gregory > > Of course that's just a very rough proposal. I've been looking mainly > at mvpp2 lately, and I'm not sure I still remember how mvneta works in > the details. > > Best regards, > > Thomas > -- > Thomas Petazzoni, CTO, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com