Thread (1 message) 1 message, 1 author, 2017-02-06

Re: [PATCH net] mlx4: Invoke softirqs after napi_reschedule

From: Eric Dumazet <hidden>
Date: 2017-02-06 17:54:01
Also in: linux-rdma

On Mon, 2017-02-06 at 09:10 -0800, Benjamin Poirier wrote:
quoted hunk
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 <redacted>
Signed-off-by: Benjamin Poirier <bpoirier-IBi9RG/b67k@public.gmane.org>
---
 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.


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