netdev - Re: [PATCH iwl-next] ice: add a separate Rx handler for flow director commands

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Message-ID: <20250409191420.GR395307@horms.kernel.org>
Date: Wed, 9 Apr 2025 20:14:20 +0100
From: Simon Horman <horms@...nel.org>
To: Michal Kubiak <michal.kubiak@...el.com>
Cc: intel-wired-lan@...ts.osuosl.org, maciej.fijalkowski@...el.com,
	netdev@...r.kernel.org, przemyslaw.kitszel@...el.com,
	Michal Swiatkowski <michal.swiatkowski@...el.com>
Subject: Re: [PATCH iwl-next] ice: add a separate Rx handler for flow
 director commands

On Fri, Mar 21, 2025 at 04:13:57PM +0100, Michal Kubiak wrote:
> The "ice" driver implementation uses the control VSI to handle
> the flow director configuration for PFs and VFs.
> 
> Unfortunately, although a separate VSI type was created to handle flow
> director queues, the Rx queue handler was shared between the flow
> director and a standard NAPI Rx handler.
> 
> Such a design approach was not very flexible. First, it mixed hotpath
> and slowpath code, blocking their further optimization. It also created
> a huge overkill for the flow director command processing, which is
> descriptor-based only, so there is no need to allocate Rx data buffers.
> 
> For the above reasons, implement a separate Rx handler for the control
> VSI. Also, remove from the NAPI handler the code dedicated to
> configuring the flow director rules on VFs.
> Do not allocate Rx data buffers to the flow director queues because
> their processing is descriptor-based only.
> Finally, allow Rx data queues to be allocated only for VSIs that have
> netdev assigned to them.
> 
> This handler splitting approach is the first step in converting the
> driver to use the Page Pool (which can only be used for data queues).
> 
> Test hints:
>   1. Create a VF for any PF managed by the ice driver.
>   2. In a loop, add and delete flow director rules for the VF, e.g.:
> 
>        for i in {1..128}; do
>            q=$(( i % 16 ))
>            ethtool -N ens802f0v0 flow-type tcp4 dst-port "$i" action "$q"
>        done
> 
>        for i in {0..127}; do
>            ethtool -N ens802f0v0 delete "$i"
>        done
> 
> Suggested-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
> Suggested-by: Michal Swiatkowski <michal.swiatkowski@...el.com>
> Acked-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
> Signed-off-by: Michal Kubiak <michal.kubiak@...el.com>

Reviewed-by: Simon Horman <horms@...nel.org>