lkml.org 
[lkml]   [2015]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [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@suse.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);
>



\
 
 \ /
  Last update: 2015-04-12 09:41    [W:0.075 / U:0.508 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site