In hot code path such as mvneta_rx_hwbm() and mvneta_rx_swbm(), we may access fields of rx_desc. The rx_desc is allocated by dma_alloc_coherent, it's uncacheable if the device isn't cache coherent, reading from uncached memory is fairly slow.
patch1 reuses the read out status to getting status field of rx_desc again. patch2 uses cacheable memory to store the rx buffer DMA address. We get the following performance data on Marvell BG4CT Platforms (tested with iperf): before the patch: recving 1GB in mvneta_rx_swbm() costs 149265960 ns after the patch: recving 1GB in mvneta_rx_swbm() costs 1421565640 ns We saved 4.76% time. RFC: can we do similar modification for tx? If yes, I can prepare a v2. Basically, these two patches do what Arnd mentioned in [1]. Hi Arnd, I added "Suggested-by you" tag, I hope you don't mind ;) Thanks [1] https://www.spinics.net/lists/netdev/msg405889.html Jisheng Zhang (2): net: mvneta: avoid getting status from rx_desc as much as possible net: mvneta: Use cacheable memory to store the rx buffer DMA address drivers/net/ethernet/marvell/mvneta.c | 36 ++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) -- 2.11.0