netdev - Re: [PATCH net-next v2] docs: networking: document NAPI

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Date:   Wed, 22 Mar 2023 01:13:38 +0100
From:   Francois Romieu <romieu@...zoreil.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
        pabeni@...hat.com, Bagas Sanjaya <bagasdotme@...il.com>,
        Toke HHHiland-JJJrgensen <toke@...hat.com>, corbet@....net,
        jesse.brandeburg@...el.com, anthony.l.nguyen@...el.com,
        pisa@....felk.cvut.cz, mkl@...gutronix.de,
        linux-doc@...r.kernel.org, f.fainelli@...il.com,
        stephen@...workplumber.org
Subject: Re: [PATCH net-next v2] docs: networking: document NAPI

Jakub Kicinski <kuba@...nel.org> :
[...]
> diff --git a/Documentation/networking/napi.rst b/Documentation/networking/napi.rst
> new file mode 100644
> index 000000000000..e9833f2b777a
> --- /dev/null
> +++ b/Documentation/networking/napi.rst
> @@ -0,0 +1,251 @@
> +.. _napi:
> +
> +====
> +NAPI
> +====
> +
> +NAPI is the event handling mechanism used by the Linux networking stack.
> +The name NAPI does not stand for anything in particular [#]_.
> +
> +In basic operation device notifies the host about new events via an interrupt.
> +The host then schedules a NAPI instance to process the events.
> +Device may also be polled for events via NAPI without receiving
> +interrupts first (:ref:`busy polling<poll>`).
> +
> +NAPI processing usually happens in the software interrupt context,
> +but user may choose to use :ref:`separate kernel threads<threaded>`
> +for NAPI processing.

NAPI processing also happens in the unusual context of netpoll.

I can't tell if it's better to be completely silent about it or to
explicitely state that it is beyond the scope of the document.

-- 
Ueimor