Re: [dpdk-dev] [PATCH v6 0/6] hide eth dev related structures

[Ajit Khaparde <ajit.khaparde@broadcom.com>]

On Mon, Oct 18, 2021 at 9:47 AM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
>
> On 10/18/2021 5:04 PM, Ali Alnubani wrote:
> >> -----Original Message-----
> >> From: dev <dev-bounces@dpdk.org> On Behalf Of Ferruh Yigit
> >> Sent: Wednesday, October 13, 2021 11:16 PM
> >> To: Konstantin Ananyev <konstantin.ananyev@intel.com>; dev@dpdk.org;
> >> jerinj@marvell.com; Ajit Khaparde <ajit.khaparde@broadcom.com>; Raslan
> >> Darawsheh <rasland@nvidia.com>; Andrew Rybchenko
> >> <andrew.rybchenko@oktetlabs.ru>; Qi Zhang <qi.z.zhang@intel.com>;
> >> Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> >> Cc: xiaoyun.li@intel.com; anoobj@marvell.com; jerinj@marvell.com;
> >> ndabilpuram@marvell.com; adwivedi@marvell.com;
> >> shepard.siegel@atomicrules.com; ed.czeck@atomicrules.com;
> >> john.miller@atomicrules.com; irusskikh@marvell.com;
> >> ajit.khaparde@broadcom.com; somnath.kotur@broadcom.com;
> >> rahul.lakkireddy@chelsio.com; hemant.agrawal@nxp.com;
> >> sachin.saxena@oss.nxp.com; haiyue.wang@intel.com; johndale@cisco.com;
> >> hyonkim@cisco.com; qi.z.zhang@intel.com; xiao.w.wang@intel.com;
> >> humin29@huawei.com; yisen.zhuang@huawei.com; oulijun@huawei.com;
> >> beilei.xing@intel.com; jingjing.wu@intel.com; qiming.yang@intel.com;
> >> Matan Azrad <matan@nvidia.com>; Slava Ovsiienko
> >> <viacheslavo@nvidia.com>; sthemmin@microsoft.com; NBU-Contact-longli
> >> <longli@microsoft.com>; heinrich.kuhn@corigine.com;
> >> kirankumark@marvell.com; andrew.rybchenko@oktetlabs.ru;
> >> mczekaj@marvell.com; jiawenwu@trustnetic.com;
> >> jianwang@trustnetic.com; maxime.coquelin@redhat.com;
> >> chenbo.xia@intel.com; NBU-Contact-Thomas Monjalon
> >> <thomas@monjalon.net>; mdr@ashroe.eu; jay.jayatheerthan@intel.com
> >> Subject: Re: [dpdk-dev] [PATCH v6 0/6] hide eth dev related structures
> >>
> >> On 10/13/2021 2:36 PM, Konstantin Ananyev wrote:
> >>> v6 changes:
> >>> - Update comments (Andrew)
> >>> - Move callback related variables under corresponding ifdefs (Andrew)
> >>> - Few nits in rte_eth_macaddrs_get (Andrew)
> >>> - Rebased on top of next-net tree
> >>>
> >>> v5 changes:
> >>> - Fix spelling (Thomas/David)
> >>> - Rename internal helper functions (David)
> >>> - Reorder patches and update commit messages (Thomas)
> >>> - Update comments (Thomas)
> >>> - Changed layout in rte_eth_fp_ops, to group functions and
> >>>      related data based on their functionality:
> >>>      first 64B line for Rx, second one for Tx.
> >>>      Didn't observe any real performance difference comparing to
> >>>      original layout. Though decided to keep a new one, as it seems
> >>>      a bit more plausible.
> >>>
> >>> v4 changes:
> >>>    - Fix secondary process attach (Pavan)
> >>>    - Fix build failure (Ferruh)
> >>>    - Update lib/ethdev/verion.map (Ferruh)
> >>>      Note that moving newly added symbols from EXPERIMENTAL to DPDK_22
> >>>      section makes checkpatch.sh to complain.
> >>>
> >>> v3 changes:
> >>>    - Changes in public struct naming (Jerin/Haiyue)
> >>>    - Split patches
> >>>    - Update docs
> >>>    - Shamelessly included Andrew's patch:
> >>>      https://patches.dpdk.org/project/dpdk/patch/20210928154856.1015020-
> >> 1-andrew.rybchenko@oktetlabs.ru/
> >>>      into these series.
> >>>      I have to do similar thing here, so decided to avoid duplicated effort.
> >>>
> >>> The aim of these patch series is to make rte_ethdev core data structures
> >>> (rte_eth_dev, rte_eth_dev_data, rte_eth_rxtx_callback, etc.) internal to
> >>> DPDK and not visible to the user.
> >>> That should allow future possible changes to core ethdev related structures
> >>> to be transparent to the user and help to improve ABI/API stability.
> >>> Note that current ethdev API is preserved, but it is a formal ABI break.
> >>>
> >>> The work is based on previous discussions at:
> >>> https://www.mail-archive.com/dev@dpdk.org/msg211405.html
> >>> https://www.mail-archive.com/dev@dpdk.org/msg216685.html
> >>> and consists of the following main points:
> >>> 1. Copy public 'fast' function pointers (rx_pkt_burst(), etc.) and
> >>>      related data pointer from rte_eth_dev into a separate flat array.
> >>>      We keep it public to still be able to use inline functions for these
> >>>      'fast' calls (like rte_eth_rx_burst(), etc.) to avoid/minimize slowdown.
> >>>      Note that apart from function pointers itself, each element of this
> >>>      flat array also contains two opaque pointers for each ethdev:
> >>>      1) a pointer to an array of internal queue data pointers
> >>>      2)  points to array of queue callback data pointers.
> >>>      Note that exposing this extra information allows us to avoid extra
> >>>      changes inside PMD level, plus should help to avoid possible
> >>>      performance degradation.
> >>> 2. Change implementation of 'fast' inline ethdev functions
> >>>      (rte_eth_rx_burst(), etc.) to use new public flat array.
> >>>      While it is an ABI breakage, this change is intended to be transparent
> >>>      for both users (no changes in user app is required) and PMD developers
> >>>      (no changes in PMD is required).
> >>>      One extra note - with new implementation RX/TX callback invocation
> >>>      will cost one extra function call with this changes. That might cause
> >>>      some slowdown for code-path with RX/TX callbacks heavily involved.
> >>>      Hope such trade-off is acceptable for the community.
> >>> 3. Move rte_eth_dev, rte_eth_dev_data, rte_eth_rxtx_callback and
> >> related
> >>>      things into internal header: <ethdev_driver.h>.
> >>>
> >>> That approach was selected to:
> >>>     - Avoid(/minimize) possible performance losses.
> >>>     - Minimize required changes inside PMDs.
> >>>
> >>> Performance testing results (ICX 2.0GHz, E810 (ice)):
> >>>    - testpmd macswap fwd mode, plus
> >>>      a) no RX/TX callbacks:
> >>>         no actual slowdown observed
> >>>      b) bpf-load rx 0 0 JM ./dpdk.org/examples/bpf/t3.o:
> >>>         ~2% slowdown
> >>>    - l3fwd: no actual slowdown observed
> >>>
> >>> Would like to thank everyone who already reviewed and tested previous
> >>> versions of these series. All other interested parties please don't be shy
> >>> and provide your feedback.
> >>>
> >>> Konstantin Ananyev (6):
> >>>     ethdev: allocate max space for internal queue array
> >>>     ethdev: change input parameters for rx_queue_count
> >>>     ethdev: copy fast-path API into separate structure
> >>>     ethdev: make fast-path functions to use new flat array
> >>>     ethdev: add API to retrieve multiple ethernet addresses
> >>>     ethdev: hide eth dev related structures
> >>>
> >>
> >> For series,
> >> Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
> >>
> >> No performance regression detected on my testing.
> >>
> >> I am merging the series to next-net now which helps testing,
> >> but before merging to main repo it will be good to get more
> >> ack and test results (I can squash new tags later).
> >>
> >> @Jerin, @Ajit, @Raslan, @Andrew, @Qi, @Honnappa,
> >> Can you please test this set for any possible regression?
> >>
> >> Series applied to dpdk-next-net/main, thanks.
> >>
> >
> > Tested (on dpdk-next-net/main) single and multi-core packet forwarding performance with testpmd on both ConnectX-5 and ConnectX-6 Dx. I didn't see any noticeable regressions.
> >
>
> Thanks!
>
> At this stage I am putting set to pull request for main repo.
> Last day for anyone who wants to test the set.
I tested dpdk-next-net/main. My testing was limited and did not reveal
any issues.