From: Nicolas Ferre <nicolas.fe...@atmel.com> Date: Wed, 5 Dec 2012 16:08:22 +0100
> On 12/04/2012 07:22 PM, David Miller : >> From: Nicolas Ferre <nicolas.fe...@atmel.com> >> Date: Mon, 3 Dec 2012 13:15:43 +0100 >> >>> Macb Ethernet controller requires a RX buffer of 128 bytes. It is >>> highly sub-optimal for Gigabit-capable GEM that is able to use >>> a bigger DMA buffer. Change this constant and associated macros >>> with data stored in the private structure. >>> I also kept the result of buffers per page calculation to lower the >>> impact of this move to a variable rx buffer size on rx hot path. >>> RX DMA buffer size has to be multiple of 64 bytes as indicated in >>> DMA Configuration Register specification. >>> >>> Signed-off-by: Nicolas Ferre <nicolas.fe...@atmel.com> >> >> This looks like it will waste a couple hundred bytes for 1500 MTU >> frames, am I right? > > Yep! But buffers get recycled, and with the current memory management by > pages, it seems that I have to rework some part of it to optimize this > memory usage (8KB memory blocks split into 5 buffers each as David said...). > > Do you think it is worth digging this way or may I rework the rx buffer > management in case of the GEM interface. If I implement a different path > for GEM interface, I will have the possibility to tailor rx DMA buffers > from 1500 Bytes up to 10KB jumbo frames... I almost think you have to. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/