Hi Stephen, On 8/30/20 9:26 PM, Stephen Hemminger wrote: > On Sun, 30 Aug 2020 15:58:57 +0300 > Andrew Rybchenko <arybche...@solarflare.com> wrote: > >>>>>>> >>>>>>> The non-zero value of rx_split_num field configures the receiving >>>>>>> queue to split ingress packets into multiple segments to the mbufs >>>>>>> allocated from various memory pools according to the specified >>>>>>> lengths. The zero value of rx_split_num field provides the backward >>>>>>> compatibility and queue should be configured in a regular way (with >>>>>>> single/multiple mbufs of the same data buffer length allocated from >>>>>>> the single memory pool). >>>>>> >>>>>> From the above description it is not 100% clear how it will coexist with: >>>>>> - existing mb_pool argument of the rte_eth_rx_queue_setup() >>>>>> - DEV_RX_OFFLOAD_SCATTER >>>>> >>>>> DEV_RX_OFFLOAD_SCATTER flag is required to be reported and configured >>>>> for the new feature to indicate the application is prepared for the >>>>> multisegment packets. >>>> >>>> I hope it will be mentioned in the feature documentation in the future, but >>>> I'm not 100% sure that it is required. See below. >>> I suppose there is the hierarchy: >>> - applications configures DEV_RX_OFFLOAD_SCATTER on the port and tells in >>> this way: >>> "Hey, driver, I'm ready to handle multi-segment packets". Readiness in >>> general. >>> - application configures BUFFER_SPLIT and tells PMD _HOW_ it wants to >>> split, in particular way: >>> "Hey, driver, please, drop ten bytes here, here and here, and the rest - >>> over there" >> >> My idea is to keep SCATTER and BUFFER_SPLIT independent. >> SCATTER is a possibility to make multi-segment packets getting >> mbufs from main rxq mempool as many as required. >> BUFFER_SPLIT is support of many mempools and splitting >> received packets as specified. > > No. > Once again, drivers should take anything from application and rely on using > logic to choose best path. Modern CPU's have good branch predictors, and > making > the developer do that work is counter productive.
Please, add a bit more details. I simply can see relationship. So, right now for me it looks like just misunderstanding. Thanks, Andrew.
