On Mon, 2017-02-06 at 09:10 -0800, Benjamin Poirier wrote:
> mlx4 may schedule napi from a workqueue. Afterwards, softirqs are not run
> in a deterministic time frame and the following message may be logged:
> NOHZ: local_softirq_pending 08
>
> The problem is the same as what was described in commit ec13ee80145c
> ("virtio_net: invoke softirqs after __napi_schedule") and this patch
> applies the same fix to mlx4.
>
> Cc: Eric Dumazet
> Signed-off-by: Benjamin Poirier
> ---
> drivers/net/ethernet/mellanox/mlx4/en_rx.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> index eac527e25ec9..14ce1549b638 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> @@ -513,10 +513,12 @@ void mlx4_en_recover_from_oom(struct mlx4_en_priv *priv)
> if (!priv->port_up)
> return;
>
> + local_bh_disable();
> for (ring = 0; ring < priv->rx_ring_num; ring++) {
> if (mlx4_en_is_ring_empty(priv->rx_ring[ring]))
> napi_reschedule(&priv->rx_cq[ring]->napi);
> }
> + local_bh_enable();
> }
>
I would prefer having the local_bh_disable()/enable inside the loop,
as done with commit 8cf699ec849f4ca1413cea01289bd7d37dbcc626
This gives more chance to service one queue at a time, avoiding to
capture all queues into one cpu.
Thanks.
