netdev - [PATCH v2 6/6] igb: avoid transmit queue timeout in xdp path

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Date:   Sat, 17 Oct 2020 09:12:38 +0200
From:   sven.auhagen@...eatech.de
To:     anthony.l.nguyen@...el.com, maciej.fijalkowski@...el.com
Cc:     davem@...emloft.net, intel-wired-lan@...ts.osuosl.org,
        netdev@...r.kernel.org, nhorman@...hat.com, sassmann@...hat.com,
        sandeep.penigalapati@...el.com, brouer@...hat.com
Subject: [PATCH v2 6/6] igb: avoid transmit queue timeout in xdp path

From: Sven Auhagen <sven.auhagen@...eatech.de>

Since we share the transmit queue with the slow path,
it is possible that we run into a transmit queue timeout.
This will reset the queue.
This happens under high load when the fast path is using the
transmit queue pretty much exclusively.

By setting the transmit queues trans_start variable to jiffies
in the two xdp xmit functions we avoid the timeout.

Signed-off-by: Sven Auhagen <sven.auhagen@...eatech.de>
---
 drivers/net/ethernet/intel/igb/igb_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 55e708f75187..4a082c06f48d 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -2916,6 +2916,8 @@ static int igb_xdp_xmit_back(struct igb_adapter *adapter, struct xdp_buff *xdp)
 
 	nq = txring_txq(tx_ring);
 	__netif_tx_lock(nq, cpu);
+	/* Avoid transmit queue timeout since we share it with the slow path */
+	nq->trans_start = jiffies;
 	ret = igb_xmit_xdp_ring(adapter, tx_ring, xdpf);
 	__netif_tx_unlock(nq);
 
@@ -2948,6 +2950,9 @@ static int igb_xdp_xmit(struct net_device *dev, int n,
 	nq = txring_txq(tx_ring);
 	__netif_tx_lock(nq, cpu);
 
+	/* Avoid transmit queue timeout since we share it with the slow path */
+	nq->trans_start = jiffies;
+
 	for (i = 0; i < n; i++) {
 		struct xdp_frame *xdpf = frames[i];
 		int err;
-- 
2.20.1