From: Jakub Kicinski <kuba@kernel•org>
To: Mina Almasry <almasrymina@google•com>, Joe Damato <jdamato@fastly•com>
Cc: davem@davemloft•net, netdev@vger•kernel.org, edumazet@google•com,
pabeni@redhat•com, andrew+netdev@lunn•ch, horms@kernel•org,
donald.hunter@gmail•com, sdf@fomichev•me, dw@davidwei•uk,
asml.silence@gmail•com, ap420073@gmail•com, dtatulea@nvidia•com,
michael.chan@broadcom•com
Subject: Re: [RFC net-next 01/22] docs: ethtool: document that rx_buf_len must control payload lengths
Date: Fri, 25 Apr 2025 15:50:34 -0700 [thread overview]
Message-ID: <20250425155034.096b7d55@kernel.org> (raw)
In-Reply-To: <CAHS8izODBjzaXObT8+i195_Kev_N80hJ_cg4jbfzrAoADW17oQ@mail.gmail.com>
On Wed, 23 Apr 2025 13:08:33 -0700 Mina Almasry wrote:
> On Mon, Apr 21, 2025 at 3:28 PM Jakub Kicinski <kuba@kernel•org> wrote:
> > @@ -971,6 +970,11 @@ completion queue size can be adjusted in the driver if CQE size is modified.
> > header / data split feature. If a received packet size is larger than this
> > threshold value, header and data will be split.
> >
> > +``ETHTOOL_A_RINGS_RX_BUF_LEN`` controls the size of the buffer chunks driver
> > +uses to receive packets. If the device uses different memory polls for headers
> > +and payload this setting may control the size of the header buffers but must
> > +control the size of the payload buffers.
>
> FWIW I don't like the ambiguity that the setting may or may not apply
> to header buffers. AFAIU header buffers are supposed to be in the
> order of tens/hundreds of bytes while the payload buffers are 1-2
> orders of magnitude larger. Why would a driver even want this setting
> to apply for both? I would prefer this setting to apply to only
> payload buffers.
Okay, I have no strong reason to leave the ambiguity.
Converging the thread with Joe:
>> Document the semantics of the rx_buf_len ethtool ring param.
>> Clarify its meaning in case of HDS, where driver may have
>> two separate buffer pools.
>
> FWIW the docs added below don't explicitly mention HDS, but I
> suppose that is implied from the multiple memory pools? Not sure if
> it's worth elucidating that.
Maybe not sufficiently. Some NICs just have buffer pools for different
sized packets, but than the buffer size should be implied by the size
range?
How about:
``ETHTOOL_A_RINGS_RX_BUF_LEN`` controls the size of the buffers driver
uses to receive packets. If the device uses different buffer pools for
headers and payload (due to HDS, HW-GRO etc.) this setting must
control the size of the payload buffers.
next prev parent reply other threads:[~2025-04-25 22:50 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-21 22:28 [RFC net-next 00/22] net: per-queue rx-buf-len configuration Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 01/22] docs: ethtool: document that rx_buf_len must control payload lengths Jakub Kicinski
2025-04-22 16:19 ` David Wei
2025-04-22 19:48 ` Joe Damato
2025-04-23 20:08 ` Mina Almasry
2025-04-25 22:50 ` Jakub Kicinski [this message]
2025-04-25 23:20 ` Joe Damato
2025-04-21 22:28 ` [RFC net-next 02/22] net: ethtool: report max value for rx-buf-len Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 03/22] net: use zero value to restore rx_buf_len to default Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 04/22] net: clarify the meaning of netdev_config members Jakub Kicinski
2025-04-22 19:57 ` Joe Damato
2025-04-21 22:28 ` [RFC net-next 05/22] net: add rx_buf_len to netdev config Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 06/22] eth: bnxt: read the page size from the adapter struct Jakub Kicinski
2025-04-23 20:35 ` Mina Almasry
2025-04-25 22:51 ` Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 07/22] eth: bnxt: set page pool page order based on rx_page_size Jakub Kicinski
2025-04-22 15:32 ` Stanislav Fomichev
2025-04-22 15:52 ` Jakub Kicinski
2025-04-22 17:27 ` Stanislav Fomichev
2025-04-21 22:28 ` [RFC net-next 08/22] eth: bnxt: support setting size of agg buffers via ethtool Jakub Kicinski
2025-04-23 21:00 ` Mina Almasry
2025-04-25 22:58 ` Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 09/22] net: move netdev_config manipulation to dedicated helpers Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 10/22] net: reduce indent of struct netdev_queue_mgmt_ops members Jakub Kicinski
2025-04-23 21:04 ` Mina Almasry
2025-04-21 22:28 ` [RFC net-next 11/22] net: allocate per-queue config structs and pass them thru the queue API Jakub Kicinski
2025-04-23 21:17 ` Mina Almasry
2025-04-25 23:24 ` Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 12/22] net: pass extack to netdev_rx_queue_restart() Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 13/22] net: add queue config validation callback Jakub Kicinski
2025-04-22 15:49 ` Stanislav Fomichev
2025-04-22 20:16 ` Joe Damato
2025-04-21 22:28 ` [RFC net-next 14/22] eth: bnxt: always set the queue mgmt ops Jakub Kicinski
2025-04-22 15:50 ` Stanislav Fomichev
2025-04-22 20:18 ` Joe Damato
2025-04-21 22:28 ` [RFC net-next 15/22] eth: bnxt: store the rx buf size per queue Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 16/22] eth: bnxt: adjust the fill level of agg queues with larger buffers Jakub Kicinski
2025-04-22 16:13 ` Stanislav Fomichev
2025-04-21 22:28 ` [RFC net-next 17/22] netdev: add support for setting rx-buf-len per queue Jakub Kicinski
2025-04-22 16:15 ` Stanislav Fomichev
2025-04-25 23:41 ` Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 18/22] net: wipe the setting of deactived queues Jakub Kicinski
2025-04-22 16:21 ` Stanislav Fomichev
2025-04-25 23:42 ` Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 19/22] eth: bnxt: use queue op config validate Jakub Kicinski
2025-04-23 10:00 ` Dragos Tatulea
2025-04-23 13:46 ` Jakub Kicinski
2025-04-23 14:24 ` Dragos Tatulea
2025-04-23 15:33 ` Jakub Kicinski
2025-06-12 11:56 ` Dragos Tatulea
2025-06-12 14:10 ` Jakub Kicinski
2025-06-12 15:52 ` Dragos Tatulea
2025-06-12 22:30 ` Jakub Kicinski
2025-06-13 19:02 ` Dragos Tatulea
2025-06-13 23:16 ` Jakub Kicinski
2025-06-17 12:36 ` Dragos Tatulea
2025-04-21 22:28 ` [RFC net-next 20/22] eth: bnxt: support per queue configuration of rx-buf-len Jakub Kicinski
2025-04-21 22:28 ` [RFC net-next 21/22] selftests: drv-net: add helper/wrapper for bpftrace Jakub Kicinski
2025-04-22 16:36 ` Stanislav Fomichev
2025-04-22 16:39 ` Stanislav Fomichev
2025-06-25 12:23 ` Breno Leitao
2025-04-21 22:28 ` [RFC net-next 22/22] selftests: drv-net: add test for rx-buf-len Jakub Kicinski
2025-04-22 17:06 ` Stanislav Fomichev
2025-04-25 23:52 ` Jakub Kicinski
2025-04-23 20:02 ` [RFC net-next 00/22] net: per-queue rx-buf-len configuration Mina Almasry
2025-04-25 23:55 ` Jakub Kicinski
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