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From: Stanislav Fomichev <stfomichev@gmail.com>
To: Mina Almasry <almasrymina@google.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org, io-uring@vger.kernel.org,
	Eric Dumazet <edumazet@google.com>,
	Willem de Bruijn <willemb@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	andrew+netdev@lunn.ch, horms@kernel.org, davem@davemloft.net,
	sdf@fomichev.me, dw@davidwei.uk, michael.chan@broadcom.com,
	dtatulea@nvidia.com, ap420073@gmail.com
Subject: Re: [RFC v1 00/22] Large rx buffer support for zcrx
Date: Tue, 29 Jul 2025 09:41:02 -0700	[thread overview]
Message-ID: <aIj5nuJJy1FVqbjC@mini-arch> (raw)
In-Reply-To: <CAHS8izPLxAQn7vK1xy+T2e+rhYnp7uX9RimEojMqNVpihPw4Rg@mail.gmail.com>

On 07/28, Mina Almasry wrote:
> On Mon, Jul 28, 2025 at 3:06 PM Stanislav Fomichev <stfomichev@gmail.com> wrote:
> >
> > On 07/28, Pavel Begunkov wrote:
> > > On 7/28/25 21:21, Stanislav Fomichev wrote:
> > > > On 07/28, Pavel Begunkov wrote:
> > > > > On 7/28/25 18:13, Stanislav Fomichev wrote:
> > > ...>>> Supporting big buffers is the right direction, but I have the same
> > > > > > feedback:
> > > > >
> > > > > Let me actually check the feedback for the queue config RFC...
> > > > >
> > > > > it would be nice to fit a cohesive story for the devmem as well.
> > > > >
> > > > > Only the last patch is zcrx specific, the rest is agnostic,
> > > > > devmem can absolutely reuse that. I don't think there are any
> > > > > issues wiring up devmem?
> > > >
> > > > Right, but the patch number 2 exposes per-queue rx-buf-len which
> > > > I'm not sure is the right fit for devmem, see below. If all you
> > >
> > > I guess you're talking about uapi setting it, because as an
> > > internal per queue parameter IMHO it does make sense for devmem.
> > >
> > > > care is exposing it via io_uring, maybe don't expose it from netlink for
> > >
> > > Sure, I can remove the set operation.
> > >
> > > > now? Although I'm not sure I understand why you're also passing
> > > > this per-queue value via io_uring. Can you not inherit it from the
> > > > queue config?
> > >
> > > It's not a great option. It complicates user space with netlink.
> > > And there are convenience configuration features in the future
> > > that requires io_uring to parse memory first. E.g. instead of
> > > user specifying a particular size, it can say "choose the largest
> > > length under 32K that the backing memory allows".
> >
> > Don't you already need a bunch of netlink to setup rss and flow
> > steering? And if we end up adding queue api, you'll have to call that
> > one over netlink also.
> >
> 
> I'm thinking one thing that could work is extending bind-rx with an
> optional rx-buf-len arg, which in the code translates into devmem
> using the new net_mp_open_rxq variant which not only restarts the
> queue but also sets the size. From there the implementation should be
> fairly straightforward in devmem. devmem currently rejects any pp for
> which pp.order != 0. It would need to start accepting that and
> forwarding the order to the gen_pool doing the allocations, etc.

Right, that's the logical alternative, to put that rx-buf-len on the
binding to control the size of the niovs. But then what do we do with
the queue's rx-buf-len? bnxt patch in the series does
page_pool_dev_alloc_frag(..., bp->rx_page_size). bp->rx_page_size comes
from netlink. Does it need to be inherited from the pp in the devmem
case somehow?

  reply	other threads:[~2025-07-29 16:41 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-28 11:04 [RFC v1 00/22] Large rx buffer support for zcrx Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 01/22] docs: ethtool: document that rx_buf_len must control payload lengths Pavel Begunkov
2025-07-28 18:11   ` Mina Almasry
2025-07-28 21:36   ` Mina Almasry
2025-08-01 23:13     ` Jakub Kicinski
2025-07-28 11:04 ` [RFC v1 02/22] net: ethtool: report max value for rx-buf-len Pavel Begunkov
2025-07-29  5:00   ` Subbaraya Sundeep
2025-07-28 11:04 ` [RFC v1 03/22] net: use zero value to restore rx_buf_len to default Pavel Begunkov
2025-07-29  5:03   ` Subbaraya Sundeep
2025-07-28 11:04 ` [RFC v1 04/22] net: clarify the meaning of netdev_config members Pavel Begunkov
2025-07-28 21:44   ` Mina Almasry
2025-08-01 23:14     ` Jakub Kicinski
2025-07-28 11:04 ` [RFC v1 05/22] net: add rx_buf_len to netdev config Pavel Begunkov
2025-07-28 21:50   ` Mina Almasry
2025-08-01 23:18     ` Jakub Kicinski
2025-07-28 11:04 ` [RFC v1 06/22] eth: bnxt: read the page size from the adapter struct Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 07/22] eth: bnxt: set page pool page order based on rx_page_size Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 08/22] eth: bnxt: support setting size of agg buffers via ethtool Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 09/22] net: move netdev_config manipulation to dedicated helpers Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 10/22] net: reduce indent of struct netdev_queue_mgmt_ops members Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 11/22] net: allocate per-queue config structs and pass them thru the queue API Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 12/22] net: pass extack to netdev_rx_queue_restart() Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 13/22] net: add queue config validation callback Pavel Begunkov
2025-07-28 22:26   ` Mina Almasry
2025-07-28 11:04 ` [RFC v1 14/22] eth: bnxt: always set the queue mgmt ops Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 15/22] eth: bnxt: store the rx buf size per queue Pavel Begunkov
2025-07-28 22:33   ` Mina Almasry
2025-08-01 23:20     ` Jakub Kicinski
2025-07-28 11:04 ` [RFC v1 16/22] eth: bnxt: adjust the fill level of agg queues with larger buffers Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 17/22] netdev: add support for setting rx-buf-len per queue Pavel Begunkov
2025-07-28 23:10   ` Mina Almasry
2025-08-01 23:37     ` Jakub Kicinski
2025-07-28 11:04 ` [RFC v1 18/22] net: wipe the setting of deactived queues Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 19/22] eth: bnxt: use queue op config validate Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 20/22] eth: bnxt: support per queue configuration of rx-buf-len Pavel Begunkov
2025-07-28 11:04 ` [RFC v1 21/22] net: parametrise mp open with a queue config Pavel Begunkov
2025-08-02  0:10   ` Jakub Kicinski
2025-08-04 12:50     ` Pavel Begunkov
2025-08-05 22:43       ` Jakub Kicinski
2025-08-06  0:05       ` Jakub Kicinski
2025-08-06 16:48       ` Mina Almasry
2025-08-06 18:11         ` Jakub Kicinski
2025-08-06 18:30           ` Mina Almasry
2025-08-06 22:05             ` Jakub Kicinski
2025-07-28 11:04 ` [RFC v1 22/22] io_uring/zcrx: implement large rx buffer support Pavel Begunkov
2025-07-28 17:13 ` [RFC v1 00/22] Large rx buffer support for zcrx Stanislav Fomichev
2025-07-28 18:18   ` Pavel Begunkov
2025-07-28 20:21     ` Stanislav Fomichev
2025-07-28 21:28       ` Pavel Begunkov
2025-07-28 22:06         ` Stanislav Fomichev
2025-07-28 22:44           ` Pavel Begunkov
2025-07-29 16:33             ` Stanislav Fomichev
2025-07-30 14:16               ` Pavel Begunkov
2025-07-30 15:50                 ` Stanislav Fomichev
2025-07-31 19:34                   ` Mina Almasry
2025-07-31 19:57                     ` Pavel Begunkov
2025-07-31 20:05                       ` Mina Almasry
2025-08-01  9:48                         ` Pavel Begunkov
2025-08-01  9:58                     ` Pavel Begunkov
2025-07-28 23:22           ` Mina Almasry
2025-07-29 16:41             ` Stanislav Fomichev [this message]
2025-07-29 17:01               ` Mina Almasry
2025-07-28 18:54 ` Mina Almasry
2025-07-28 19:42   ` Pavel Begunkov
2025-07-28 20:23     ` Mina Almasry
2025-07-28 20:57       ` Pavel Begunkov

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