Re: [PATCH net-next] eth: mlx5: link NAPI instances to queues and IRQs

[Joe Damato <jdamato@fastly.com>]

On Tue, Feb 06, 2024 at 09:10:27PM +0200, Tariq Toukan wrote:
> 
> 
> On 06/02/2024 19:12, Joe Damato wrote:
> >On Tue, Feb 06, 2024 at 10:11:28AM +0200, Tariq Toukan wrote:
> >>
> >>
> >>On 06/02/2024 3:03, Joe Damato wrote:
> >>>Make mlx5 compatible with the newly added netlink queue GET APIs.
> >>>
> >>>Signed-off-by: Joe Damato <jdamato@fastly.com>
> >>
> >>+ Gal
> >>
> >>Hi Joe,
> >>Thanks for your patch.
> >>
> >>We have already prepared a similar patch, and it's part of our internal
> >>submission queue, and planned to be submitted soon.
> >>
> >>Please see my comments below, let us know if you're welling to respin a V2
> >>or wait for our patch.
> >
> >Do you have a rough estimate on when it'll be submitted?
> >
> >If it's several months out I'll try again, but if it's expected to be
> >submit in the next few weeks I'll wait for your official change.
> 
> It'll be in the next few weeks.

OK, well I tweaked the v3 I had queued  based on your feedback. I am
definitiely not an mlx5 expert, so I have no idea if it's correct.

The changes can be summed up as:
  - mlx5e_activate_channel and mlx5e_deactivate_channel to use
    netif_queue_set_napi for each mlx5e_txqsq as it is
    activated/deactivated. I assumed sq->txq_ix is the correct index, but I
    have no idea.
  - mlx5e_activate_qos_sq and mlx5e_deactivate_qos_sq to handle the QOS/HTB
    case, similar to the above.
  - IRQ storage removed

If you think that sounds vaguely correct, I can send the v3 tomorrow when
it has been >24hrs as per Rahul's request.

> >
> >BTW, are the per queue coalesce changes in that same queue? It was
> >mentioned previously [1] that this feature is coming after we submit a
> >simple attempt as an RFC. If that feature isn't planned or won't be submit
> >anytime soon, can you let us know and we can try to attempt an RFC v3 for
> >it?
> >
> 
> The per queue coalesce series is going through internal code review, and is
> expected to also be ready in a matter of a few weeks.

OK, great. Thanks for letting me know; we are definitely interested in
using this feature.

> >[1]: https://lore.kernel.org/lkml/874jj34e67.fsf@nvidia.com/
> >
> >>>---
> >>>  drivers/net/ethernet/mellanox/mlx5/core/en.h      | 1 +
> >>>  drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 8 ++++++++
> >>>  2 files changed, 9 insertions(+)
> >>>
> >>>diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> >>>index 55c6ace0acd5..3f86ee1831a8 100644
> >>>--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
> >>>+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
> >>>@@ -768,6 +768,7 @@ struct mlx5e_channel {
> >>>  	u16                        qos_sqs_size;
> >>>  	u8                         num_tc;
> >>>  	u8                         lag_port;
> >>>+	unsigned int		   irq;
> >>>  	/* XDP_REDIRECT */
> >>>  	struct mlx5e_xdpsq         xdpsq;
> >>>diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> >>>index c8e8f512803e..e1bfff1fb328 100644
> >>>--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> >>>+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> >>>@@ -2473,6 +2473,9 @@ static void mlx5e_close_queues(struct mlx5e_channel *c)
> >>>  	mlx5e_close_tx_cqs(c);
> >>>  	mlx5e_close_cq(&c->icosq.cq);
> >>>  	mlx5e_close_cq(&c->async_icosq.cq);
> >>>+
> >>>+	netif_queue_set_napi(c->netdev, c->ix, NETDEV_QUEUE_TYPE_TX, NULL);
> >>>+	netif_queue_set_napi(c->netdev, c->ix, NETDEV_QUEUE_TYPE_RX, NULL);
> >>>  }
> >>>  static u8 mlx5e_enumerate_lag_port(struct mlx5_core_dev *mdev, int ix)
> >>>@@ -2558,6 +2561,7 @@ static int mlx5e_open_channel(struct mlx5e_priv *priv, int ix,
> >>>  	c->stats    = &priv->channel_stats[ix]->ch;
> >>>  	c->aff_mask = irq_get_effective_affinity_mask(irq);
> >>>  	c->lag_port = mlx5e_enumerate_lag_port(priv->mdev, ix);
> >>>+	c->irq		= irq;
> >>>  	netif_napi_add(netdev, &c->napi, mlx5e_napi_poll);
> >>>@@ -2602,6 +2606,10 @@ static void mlx5e_activate_channel(struct mlx5e_channel *c)
> >>>  		mlx5e_activate_xsk(c);
> >>>  	else
> >>>  		mlx5e_activate_rq(&c->rq);
> >>>+
> >>>+	netif_napi_set_irq(&c->napi, c->irq);
> >>
> >>Can be safely moved to mlx5e_open_channel without interfering with other
> >>existing mapping. This would save the new irq field in mlx5e_channel.
> >
> >Sure, yea, I have that change queued already from last night.
> >
> 
> I see now.. I replied before noticing it.
> 
> >>>+	netif_queue_set_napi(c->netdev, c->ix, NETDEV_QUEUE_TYPE_TX, &c->napi);
> >>
> >>In some configurations we have multiple txqs per channel, so the txq indices
> >>are not 1-to-1 with their channel index.
> >>
> >>This should be called per each txq, with the proper txq index.
> >>
> >>It should be done also for feture-dedicated SQs (like QOS/HTB).
> >
> >OK. I think the above makes sense and I'll look into it if I have some time
> >this week.
> >>>+	netif_queue_set_napi(c->netdev, c->ix, NETDEV_QUEUE_TYPE_RX, &c->napi);
> >>
> >>For consistency, I'd move this one as well, to match the TX handling.
> >
> >Sure.
> >
> >>>  }
> >>>  static void mlx5e_deactivate_channel(struct mlx5e_channel *c)