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

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Message-ID: <aCSNqWh0Cbh3rfdE@localhost.localdomain>
Date: Wed, 14 May 2025 14:33:45 +0200
From: Michal Kubiak <michal.kubiak@...el.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
CC: <intel-wired-lan@...ts.osuosl.org>, <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 Wed, May 14, 2025 at 12:26:40PM +0200, Maciej Fijalkowski wrote:
> 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>
> > ---
> 
> (...)
> 
> > diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.h b/drivers/net/ethernet/intel/ice/ice_txrx.h
> > index 4b63081629d0..041768df0b23 100644
> > --- a/drivers/net/ethernet/intel/ice/ice_txrx.h
> > +++ b/drivers/net/ethernet/intel/ice/ice_txrx.h
> > @@ -492,6 +492,7 @@ static inline unsigned int ice_rx_pg_order(struct ice_rx_ring *ring)
> >  
> >  union ice_32b_rx_flex_desc;
> >  
> > +void ice_init_ctrl_rx_descs(struct ice_rx_ring *rx_ring, u32 num_descs);
> >  bool ice_alloc_rx_bufs(struct ice_rx_ring *rxr, unsigned int cleaned_count);
> >  netdev_tx_t ice_start_xmit(struct sk_buff *skb, struct net_device *netdev);
> >  u16
> > @@ -512,4 +513,5 @@ ice_prgm_fdir_fltr(struct ice_vsi *vsi, struct ice_fltr_desc *fdir_desc,
> >  		   u8 *raw_packet);
> >  int ice_clean_rx_irq(struct ice_rx_ring *rx_ring, int budget);
> 
> this can now become static as it's not called from ice_lib.c anymore.
> can you address this in v2 if this patch got lost and has not been merged
> yet?
> 

Makes sense.
OK, I will prepare a quick v2 with this change only.

Thanks,
Michal

> >  void ice_clean_ctrl_tx_irq(struct ice_tx_ring *tx_ring);
> > +void ice_clean_ctrl_rx_irq(struct ice_rx_ring *rx_ring);
> >  #endif /* _ICE_TXRX_H_ */
> > -- 
> > 2.45.2
> >