Re: [dpdk-dev] [PATCH v13 0/7] ethdev: introduce shared Rx queue

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 10/21/2021 11:41 AM, Xueming Li wrote:
> In current DPDK framework, all Rx queues is pre-loaded with mbufs for
> incoming packets. When number of representors scale out in a switch
> domain, the memory consumption became significant. Further more,
> polling all ports leads to high cache miss, high latency and low
> throughputs.
> 
> This patch introduces shared Rx queue. PF and representors in same
> Rx domain and switch domain could share Rx queue set by specifying
> non-zero share group value in Rx queue configuration.
> 
> All ports that share Rx queue actually shares hardware descriptor
> queue and feed all Rx queues with one descriptor supply, memory is saved.
> 
> Polling any queue using same shared Rx queue receives packets from all
> member ports. Source port is identified by mbuf->port.
> 
> Multiple groups is supported by group ID. Port queue number in a shared
> group should be identical. Queue index is 1:1 mapped in shared group.
> An example of two share groups:
>   Group1, 4 shared Rx queues per member port: PF, repr0, repr1
>   Group2, 2 shared Rx queues per member port: repr2, repr3, ... repr127
>   Poll first port for each group:
>    core	port	queue
>    0	0	0
>    1	0	1
>    2	0	2
>    3	0	3
>    4	2	0
>    5	2	1
> 
> Shared Rx queue must be polled on single thread or core. If both PF0 and
> representor0 joined same share group, can't poll pf0rxq0 on core1 and
> rep0rxq0 on core2. Actually, polling one port within share group is
> sufficient since polling any port in group will return packets for any
> port in group.
> 
> There was some discussion to aggregate member ports in same group into a
> dummy port, several ways to achieve it. Since it optional, need to collect
> more feedback and requirement from user, make better decision later.
> 
> v1:
>    - initial version
> v2:
>    - add testpmd patches
> v3:
>    - change common forwarding api to macro for performance, thanks Jerin.
>    - save global variable accessed in forwarding to flowstream to minimize
>      cache miss
>    - combined patches for each forwarding engine
>    - support multiple groups in testpmd "--share-rxq" parameter
>    - new api to aggregate shared rxq group
> v4:
>    - spelling fixes
>    - remove shared-rxq support for all forwarding engines
>    - add dedicate shared-rxq forwarding engine
> v5:
>   - fix grammars
>   - remove aggregate api and leave it for later discussion
>   - add release notes
>   - add deployment example
> v6:
>   - replace RxQ offload flag with device offload capability flag
>   - add Rx domain
>   - RxQ is shared when share group > 0
>   - update testpmd accordingly
> v7:
>   - fix testpmd share group id allocation
>   - change rx_domain to 16bits
> v8:
>   - add new patch for testpmd to show device Rx domain ID and capability
>   - new share_qid in RxQ configuration
> v9:
>   - fix some spelling
> v10:
>   - add device capability name api
> v11:
>   - remove macro from device capability name list
> v12:
>   - rephrase
>   - in forwarding core check, add  global flag and RxQ enabled check
> v13:
>   - update imports of new forwarding engine
>   - rephrase
> 
> Xueming Li (7):
>    ethdev: introduce shared Rx queue
>    ethdev: get device capability name as string
>    app/testpmd: dump device capability and Rx domain info
>    app/testpmd: new parameter to enable shared Rx queue
>    app/testpmd: dump port info for shared Rx queue
>    app/testpmd: force shared Rx queue polled on same core
>    app/testpmd: add forwarding engine for shared Rx queue
> 

This patch is changing some common ethdev structs for a use case I am
not sure how common, I would like to see more reviews from more vendors
but we didn't get, at this stage I will proceed based on Andres's review.

Since only nvidia will be able to test this feature in this release, can
you please be sure nvidia test report contains this feature? To be sure
the feature is tested at least by a vendor.


Series applied to dpdk-next-net/main, thanks.