netdev - RE: [Intel-wired-lan] [PATCH net 0/5] idpf: replace Tx flow scheduling buffer ring with buffer pool

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Message-ID: <DM4PR11MB6502C412C043F2560FC468FDD443A@DM4PR11MB6502.namprd11.prod.outlook.com>
Date: Thu, 3 Jul 2025 20:21:17 +0000
From: "Hay, Joshua A" <joshua.a.hay@...el.com>
To: Paul Menzel <pmenzel@...gen.mpg.de>
CC: "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [Intel-wired-lan] [PATCH net 0/5] idpf: replace Tx flow
 scheduling buffer ring with buffer pool

> >> Am 25.06.25 um 18:11 schrieb Joshua Hay:
> >>> This series fixes a stability issue in the flow scheduling Tx send/clean
> >>> path that results in a Tx timeout.
> >>>
> >>> The existing guardrails in the Tx path were not sufficient to prevent
> >>> the driver from reusing completion tags that were still in flight (held
> >>> by the HW).  This collision would cause the driver to erroneously clean
> >>> the wrong packet thus leaving the descriptor ring in a bad state.
> >>>
> >>> The main point of this refactor is replace the flow scheduling buffer
> >>
> >> … to replace …?
> >
> > Thanks, will fix in v2
> >
> >>> ring with a large pool/array of buffers.  The completion tag then simply
> >>> is the index into this array.  The driver tracks the free tags and pulls
> >>> the next free one from a refillq.  The cleaning routines simply use the
> >>> completion tag from the completion descriptor to index into the array to
> >>> quickly find the buffers to clean.
> >>>
> >>> All of the code to support the refactor is added first to ensure traffic
> >>> still passes with each patch.  The final patch then removes all of the
> >>> obsolete stashing code.
> >>
> >> Do you have reproducers for the issue?
> >
> > This issue cannot be reproduced without the customer specific device
> > configuration, but it can impact any traffic once in place.
> 
> Interesting. Then it’d be great if you could describe that setup in more
> detail.

Hi Paul, I'm still working with the customer on what details can be provided. I will add what I can to the cover letter in v2.

> 
> >>> Joshua Hay (5):
> >>>     idpf: add support for Tx refillqs in flow scheduling mode
> >>>     idpf: improve when to set RE bit logic
> >>>     idpf: replace flow scheduling buffer ring with buffer pool
> >>>     idpf: stop Tx if there are insufficient buffer resources
> >>>     idpf: remove obsolete stashing code
> >>>
> >>>    .../ethernet/intel/idpf/idpf_singleq_txrx.c   |   6 +-
> >>>    drivers/net/ethernet/intel/idpf/idpf_txrx.c   | 626 ++++++------------
> >>>    drivers/net/ethernet/intel/idpf/idpf_txrx.h   |  76 +--
> >>>    3 files changed, 239 insertions(+), 469 deletions(-)
> 
> 
> Kind regards,
> 
> Paul

Thanks,
Josh