netdev - RE: [PATCH V1 net-next 5/5] net: ena: Add devlink documentation

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Message-ID: <a5032fe447a044c08135814aa906ae70@amazon.com>
Date:   Tue, 10 Jan 2023 15:20:55 +0000
From:   "Arinzon, David" <darinzon@...zon.com>
To:     "Iwashima, Kuniyuki" <kuniyu@...zon.co.jp>
CC:     "Kiyanovski, Arthur" <akiyano@...zon.com>,
        "Saidi, Ali" <alisaidi@...zon.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "Itzko, Shahar" <itzko@...zon.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "Matushevsky, Alexander" <matua@...zon.com>,
        "Bshara, Nafea" <nafea@...zon.com>,
        "Dagan, Noam" <ndagan@...zon.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Abboud, Osama" <osamaabb@...zon.com>,
        "Bshara, Saeed" <saeedb@...zon.com>,
        "Agroskin, Shay" <shayagr@...zon.com>,
        "Machulsky, Zorik" <zorik@...zon.com>
Subject: RE: [PATCH V1 net-next 5/5] net: ena: Add devlink documentation

Good catch! Thanks.
This will be addressed in the next version of the patchset.

> -----Original Message-----
> From: Iwashima, Kuniyuki <kuniyu@...zon.co.jp>
> Sent: Monday, January 9, 2023 8:00 AM
> To: Arinzon, David <darinzon@...zon.com>
> Cc: Kiyanovski, Arthur <akiyano@...zon.com>; Saidi, Ali
> <alisaidi@...zon.com>; davem@...emloft.net; Itzko, Shahar
> <itzko@...zon.com>; kuba@...nel.org; Matushevsky, Alexander
> <matua@...zon.com>; Bshara, Nafea <nafea@...zon.com>; Dagan,
> Noam <ndagan@...zon.com>; netdev@...r.kernel.org; Abboud, Osama
> <osamaabb@...zon.com>; Bshara, Saeed <saeedb@...zon.com>;
> Agroskin, Shay <shayagr@...zon.com>; Machulsky, Zorik
> <zorik@...zon.com>; Iwashima, Kuniyuki <kuniyu@...zon.co.jp>
> Subject: Re: [PATCH V1 net-next 5/5] net: ena: Add devlink documentation
> 
> From:   David Arinzon <darinzon@...zon.com>
> Date:   Sun, 8 Jan 2023 10:35:33 +0000
> > Update the documentation with a devlink section, the added files, as
> > well as large LLQ enablement.
> >
> > Signed-off-by: Shay Agroskin <shayagr@...zon.com>
> > Signed-off-by: David Arinzon <darinzon@...zon.com>
> > ---
> >  .../device_drivers/ethernet/amazon/ena.rst    | 30
> +++++++++++++++++++
> 
> Each driver's devlink doc exists under Documentation/networking/devlink/
> and linked from index.html there.
> 
> We should duplicate this doc under Documentation/networking/devlink/
> or link from the index.html ?
> 
> 
> >  1 file changed, 30 insertions(+)
> >
> > diff --git
> > a/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
> > b/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
> > index 8bcb173e0353..1229732a8c91 100644
> > ---
> a/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
> > +++
> b/Documentation/networking/device_drivers/ethernet/amazon/ena.rst
> > @@ -53,6 +53,7 @@ ena_common_defs.h   Common definitions for
> ena_com layer.
> >  ena_regs_defs.h     Definition of ENA PCI memory-mapped (MMIO)
> registers.
> >  ena_netdev.[ch]     Main Linux kernel driver.
> >  ena_ethtool.c       ethtool callbacks.
> > +ena_devlink.[ch]    devlink files (see `devlink support`_ for more info)
> >  ena_pci_id_tbl.h    Supported device IDs.
> >  =================
> ======================================================
> >
> > @@ -253,6 +254,35 @@ RSS
> >  - The user can provide a hash key, hash function, and configure the
> >    indirection table through `ethtool(8)`.
> >
> > +.. _`devlink support`:
> > +DEVLINK SUPPORT
> > +===============
> > +.. _`devlink`:
> >
> +https://www.kernel.org/doc/html/latest/networking/devlink/index.html
> > +
> > +`devlink`_ supports toggling LLQ entry size between the default 128
> > +bytes and 256 bytes.
> > +A 128 bytes entry size allows for a maximum of 96 bytes of packet
> > +header size which sometimes is not enough (e.g. when using tunneling).
> > +Increasing LLQ entry size to 256 bytes, allows a maximum header size
> > +of 224 bytes. This comes with the penalty of reducing the number of
> > +LLQ entries in the TX queue by 2 (i.e. from 1024 to 512).
> > +
> > +The entry size can be toggled by enabling/disabling the
> > +large_llq_header devlink param and reloading the driver to make it take
> effect, e.g.
> > +
> > +.. code-block:: shell
> > +
> > +  sudo devlink dev param set pci/0000:00:06.0 name large_llq_header
> > + value true cmode driverinit  sudo devlink dev reload
> > + pci/0000:00:06.0
> > +
> > +One way to verify that the TX queue entry size has indeed increased
> > +is to check that the maximum TX queue depth is 512. This can be
> > +checked, for example, by
> > +using:
> > +
> > +.. code-block:: shell
> > +
> > +  ethtool -g [interface]
> > +
> >  DATA PATH
> >  =========
> >
> > --
> > 2.38.1