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Date: Sun, 12 Apr 2015 10:03:04 +0300 From: Ido Shamay <idos@....mellanox.co.il> To: Benjamin Poirier <bpoirier@...e.de>, Amir Vadai <amirv@...lanox.com> CC: netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] mlx4: Fix tx ring affinity_mask creation Hi Benjamin, On 4/10/2015 7:27 PM, Benjamin Poirier wrote: > By default, the number of tx queues is limited by the number of online cpus in > mlx4_en_get_profile(). However, this limit no longer holds after the ethtool > .set_channels method has been called. In that situation, the driver may access > invalid bits of certain cpumask variables when queue_index > nr_cpu_ids. I must say I don't see the above issue with the current code. Whatever is the modified value of priv->num_tx_rings_p_up, it will set XPS only on queues which have been set with CPU affinity mask (no access to invalid bits). It's true that when priv->num_tx_rings_p_up > nr_cpus. not all queues will be set with XPS. This is because the code tries to preserve 1:1 mapping of queues to cores, to avoid a double mapping of queues to cores. I guess it's ok to break the 1:1 mapping in this condition, but the commit message should say that instead of invalid bits. Please fix me if I'm wrong. > Signed-off-by: Benjamin Poirier <bpoirier@...e.de> > --- > drivers/net/ethernet/mellanox/mlx4/en_tx.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c > index 55f9f5c..8c234ec 100644 > --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c > +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c > @@ -143,8 +143,10 @@ int mlx4_en_create_tx_ring(struct mlx4_en_priv *priv, > ring->hwtstamp_tx_type = priv->hwtstamp_config.tx_type; > ring->queue_index = queue_index; > > - if (queue_index < priv->num_tx_rings_p_up && cpu_online(queue_index)) > - cpumask_set_cpu(queue_index, &ring->affinity_mask); > + if (queue_index < priv->num_tx_rings_p_up) > + cpumask_set_cpu_local_first(queue_index, > + priv->mdev->dev->numa_node, > + &ring->affinity_mask); Moving from cpumask_set_cpu to cpumask_set_cpu_local_first is great, but should come in a different commit, since the behavior of the XPS is changed here (xps_cpus[tx_ring[queue_index]] != queue_index from now). Commit should state of this behavior change. Thanks a lot Benjamin. > > *pring = ring; > return 0; > @@ -213,7 +215,7 @@ int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv, > > err = mlx4_qp_to_ready(mdev->dev, &ring->wqres.mtt, &ring->context, > &ring->qp, &ring->qp_state); > - if (!user_prio && cpu_online(ring->queue_index)) > + if (!cpumask_empty(&ring->affinity_mask)) > netif_set_xps_queue(priv->dev, &ring->affinity_mask, > ring->queue_index); > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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