On 3/6/2023 1:26 PM, Morten Brørup wrote: >> From: Ferruh Yigit [mailto:ferruh.yi...@amd.com] >> Sent: Monday, 6 March 2023 13.49 >> >> On 1/4/2023 8:21 AM, Morten Brørup wrote: >>>> From: Feifei Wang [mailto:feifei.wa...@arm.com] >>>> Sent: Wednesday, 4 January 2023 08.31 >>>> >>>> Add 'tx_fill_sw_ring' and 'rx_flush_descriptor' API into direct rearm >>>> mode for separate Rx and Tx Operation. And this can support different >>>> multiple sources in direct rearm mode. For examples, Rx driver is >>>> ixgbe, >>>> and Tx driver is i40e. >>>> >>>> Suggested-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> >>>> Suggested-by: Ruifeng Wang <ruifeng.w...@arm.com> >>>> Signed-off-by: Feifei Wang <feifei.wa...@arm.com> >>>> Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com> >>>> Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> >>>> --- >>> >>> This feature looks very promising for performance. I am pleased to see >> progress on it. >>> >> >> Hi Morten, >> >> Yes it brings some performance, but not to generic use case, only to >> specific and constraint use case. > > I got the impression that the supported use case is a prominent and important > use case. >
Can you please give real life samples for this use case, other than just showing better performance number in the test bench? This helps to understand the reasoning better. > This is the primary argument for considering such a complex non-generic > feature. > >> >> And changes are relatively invasive comparing the usecase it supports, >> like it adds new two inline datapath functions and a new dev_ops. >> >> I am worried the unnecessary complexity and possible regressions in the >> fundamental and simple parts of the project, with a good intention to >> gain a few percentage performance in a specific usecase, can hurt the >> project. >> >> >> I can see this is compared to MBUF_FAST_FREE feature, but MBUF_FAST_FREE >> is just an offload benefiting from existing offload infrastructure, >> which requires very small update and logically change in application and >> simple to implement in the drivers. So, they are not same from >> complexity perspective. >> >> Briefly, I am not comfortable with this change, I would like to see an >> explicit approval and code review from techboard to proceed. > > I agree that the complexity is very high, and thus requires extra > consideration. Your suggested techboard review and approval process seems > like a good solution. > > And the performance benefit of direct rearm should be compared to the > performance using the new zero-copy mempool API. > > -Morten >
