linux-kernel - [PATCH net-next v2 4/4] virtio_net: Use persistent NAPI config

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Message-Id: <20250116055302.14308-5-jdamato@fastly.com>
Date: Thu, 16 Jan 2025 05:52:59 +0000
From: Joe Damato <jdamato@...tly.com>
To: netdev@...r.kernel.org
Cc: gerhard@...leder-embedded.com,
	jasowang@...hat.com,
	leiyang@...hat.com,
	mkarsten@...terloo.ca,
	Joe Damato <jdamato@...tly.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	virtualization@...ts.linux.dev (open list:VIRTIO CORE AND NET DRIVERS),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net-next v2 4/4] virtio_net: Use persistent NAPI config

Use persistent NAPI config so that NAPI IDs are not renumbered as queue
counts change.

$ sudo ethtool -l ens4  | tail -5 | egrep -i '(current|combined)'
Current hardware settings:
Combined:	4

$ ./tools/net/ynl/pyynl/cli.py \
    --spec Documentation/netlink/specs/netdev.yaml \
    --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'rx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'type': 'tx'},
 {'id': 1, 'ifindex': 2, 'type': 'tx'},
 {'id': 2, 'ifindex': 2, 'type': 'tx'},
 {'id': 3, 'ifindex': 2, 'type': 'tx'}]

Now adjust the queue count, note that the NAPI IDs are not renumbered:

$ sudo ethtool -L ens4 combined 1
$ ./tools/net/ynl/pyynl/cli.py \
    --spec Documentation/netlink/specs/netdev.yaml \
    --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'type': 'tx'}]

$ sudo ethtool -L ens4 combined 8
$ ./tools/net/ynl/pyynl/cli.py \
    --spec Documentation/netlink/specs/netdev.yaml \
    --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'rx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'rx'},
 {'id': 4, 'ifindex': 2, 'napi-id': 8197, 'type': 'rx'},
 {'id': 5, 'ifindex': 2, 'napi-id': 8198, 'type': 'rx'},
 {'id': 6, 'ifindex': 2, 'napi-id': 8199, 'type': 'rx'},
 {'id': 7, 'ifindex': 2, 'napi-id': 8200, 'type': 'rx'},
 [...]

Signed-off-by: Joe Damato <jdamato@...tly.com>
---
 v2:
   - New in this v2. Adds persistent NAPI config so that NAPI IDs are
     not renumbered and napi_config settings are persisted.

 drivers/net/virtio_net.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index c6fda756dd07..52094596e94b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -6420,8 +6420,9 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
 	INIT_DELAYED_WORK(&vi->refill, refill_work);
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		vi->rq[i].pages = NULL;
-		netif_napi_add_weight(vi->dev, &vi->rq[i].napi, virtnet_poll,
-				      napi_weight);
+		netif_napi_add_config(vi->dev, &vi->rq[i].napi, virtnet_poll,
+				      i);
+		vi->rq[i].napi.weight = napi_weight;
 		netif_napi_add_tx_weight(vi->dev, &vi->sq[i].napi,
 					 virtnet_poll_tx,
 					 napi_tx ? napi_weight : 0);
-- 
2.25.1