Re: [DPDK 24.11.3-rc1] rte_flow_async_create() stucks in while loop (infinite loop)

[배성종 <sjbae1999@gmail.com>]

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Hello,

@Ivan Malov, I use one flow queue per lcore.

Sincerely,
*Seongjong Bae *M.S. Student T-Networking Lab.

*Email.* sjbae1999@gmail.com
*Mobile.* (+82)01089640524
*Web.* https://tnet.snu.ac.kr/


2025년 8월 12일 (화) 오후 5:30, Bing Zhao <bingz@nvidia.com>님이 작성:

> @Ivan Malov, which version of DPDK are you using? The last year RC?
>
> @Erez Shitrit, could you help to confirm if the GCC loop expansion bug of
> some arm compiler is also present in this branch?
> I remember there was a GCC bug to always compare with 1 and jump into an
> infinite loop.
>
> Thanks
>
> > -----Original Message-----
> > From: Ivan Malov <ivan.malov@arknetworks.am>
> > Sent: Tuesday, August 12, 2025 12:09 AM
> > To: 배성종 <sjbae1999@gmail.com>
> > Cc: users@dpdk.org; Dariusz Sosnowski <dsosnowski@nvidia.com>; Slava
> > Ovsiienko <viacheslavo@nvidia.com>; Bing Zhao <bingz@nvidia.com>; Ori
> Kam
> > <orika@nvidia.com>; Suanming Mou <suanmingm@nvidia.com>; Matan Azrad
> > <matan@nvidia.com>
> > Subject: Re: [DPDK 24.11.3-rc1] rte_flow_async_create() stucks in while
> > loop (infinite loop)
> >
> > External email: Use caution opening links or attachments
> >
> >
> > Hi,
> >
> > On Mon, 28 Jul 2025, 배성종 wrote:
> >
> > > Hello commit authors (and maintainers),
> > >
> > > I'm currently working with rte_flow_async_create() using the postpone
> > > flag, along with rte_flow_push/pull() for batching, in a scenario
> > involving thousands of flows on a BlueField-2 system.
> > >
> > > My goal is to implement hardware steering such that ingress traffic
> > bypasses the ARM core of the BF2, and egress traffic does the same.
> > >
> > > According to the DPDK documentation, rte_flow_push/pull() seems to be
> > > intended for use as a batch operation, wrapping a large for loop that
> > issues multiple flow operations, and then committing them to hardware in
> > one go.
> > >
> > > However, I’ve observed that when multiple cores simultaneously insert
> > > flow rules, using rte_flow_push/pull() in such a batched way can result
> > in the rule insertion operations not being properly transmitted to the
> > hardware. Specifically, the internal function mlx5dr_send_all_dep_wqe()
> > ends up getting stuck in its while loop.
> > >
> > > Interestingly, if I call rte_flow_push/pull() after each individual
> > > rte_flow_async_create() operation, even though that usage seems
> contrary
> > to the intended batching model, the infinite loop issue is significantly
> > mitigated. The frequency of getting stuck in mlx5dr_send_all_dep_wqe()
> > drops drastically—though it still occurs occasionally.
> > >
> > > In summary, calling rte_flow_push/pull() after each
> > rte_flow_async_create() seems to avoid the infinite loop, but I’m unsure
> > if this is an expected usage pattern. I would like to ask:
> > >
> > >  *
> > >
> > >     Is this behavior intentional?
> > >
> > >  *
> > >
> > >     Am I misunderstanding the design or usage expectations for
> > rte_flow_push/pull() in multi-core scenarios?
> > >
> >
> > Perhaps my question is a bit out of place and wrong, but, given the fact
> > there are no code snippets to take a look at, are you using separate flow
> > queues for submitting the operations, one flow queue per lcore?
> >
> > Thank you.
> >
> > > Thank you for your time and support.
> > >
> > > Sincerely,
> > > Seongjong Bae M.S. Student T-Networking Lab.
> > > [AIorK4yCWXBmHrQ1GGSZ1Kc18irHfB1S9x_FqTeAHsxNIdnf_olG-PRjFVlItUw34zr1t
> > > nNwkP5AlPTomK87]
> > > Email
> > > sjbae1999@gmail.com
> > > Mobile
> > > (+82)01089640524
> > > Web.
> > > https://tnet.snu.ac.kr/
> > > [a81b6766e3d5b6518dc4010493c7772f5a46f598.png?u=11013800]
> > >
> > >
>

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