virtio-net has two ways to switch napi_tx: one is through the
module parameter, and the other is through coalescing parameter
settings (provided that the nic status is down).
Sometimes we face performance regression caused by napi_tx,
then we need to switch napi_tx when debugging. However, the
existing methods are a bit troublesome, such as needing to
reload the driver or turn off the network card. So try to make
this update.
Signed-off-by: Heng Qi <hen...@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---
drivers/net/virtio_net.c | 81 ++++++++++++++++++----------------------
1 file changed, 37 insertions(+), 44 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 10614e9f7cad..12f8e1f9971c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3559,16 +3559,37 @@ static int virtnet_coal_params_supported(struct
ethtool_coalesce *ec)
return 0;
}
-static int virtnet_should_update_vq_weight(int dev_flags, int weight,
- int vq_weight, bool *should_update)
+static void virtnet_switch_napi_tx(struct virtnet_info *vi, u32 qstart,
+ u32 qend, u32 tx_frames)
{
- if (weight ^ vq_weight) {
- if (dev_flags & IFF_UP)
- return -EBUSY;
- *should_update = true;
- }
+ struct net_device *dev = vi->dev;
+ int new_weight, cur_weight;
+ struct netdev_queue *txq;
+ struct send_queue *sq;
- return 0;
+ new_weight = tx_frames ? NAPI_POLL_WEIGHT : 0;
+ for (; qstart < qend; qstart++) {
+ sq = &vi->sq[qstart];
+ cur_weight = sq->napi.weight;
+ if (!(new_weight ^ cur_weight))
+ continue;
+
+ if (!(dev->flags & IFF_UP)) {
+ sq->napi.weight = new_weight;
+ continue;
+ }
+
+ if (cur_weight)
+ virtnet_napi_tx_disable(&sq->napi);
+
+ txq = netdev_get_tx_queue(dev, qstart);
+ __netif_tx_lock_bh(txq);
+ sq->napi.weight = new_weight;
+ __netif_tx_unlock_bh(txq);
+
+ if (!cur_weight)
+ virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
+ }
}
static int virtnet_set_coalesce(struct net_device *dev,
@@ -3577,25 +3598,11 @@ static int virtnet_set_coalesce(struct net_device *dev,
struct netlink_ext_ack *extack)
{
struct virtnet_info *vi = netdev_priv(dev);
- int ret, queue_number, napi_weight;
- bool update_napi = false;
-
- /* Can't change NAPI weight if the link is up */
- napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
- for (queue_number = 0; queue_number < vi->max_queue_pairs;
queue_number++) {
- ret = virtnet_should_update_vq_weight(dev->flags, napi_weight,
-
vi->sq[queue_number].napi.weight,
- &update_napi);
- if (ret)
- return ret;
-
- if (update_napi) {
- /* All queues that belong to [queue_number,
vi->max_queue_pairs] will be
- * updated for the sake of simplicity, which might not
be necessary
- */
- break;
- }
- }
+ int ret;
+
+ /* Param tx_frames can be used to switch napi_tx */
+ virtnet_switch_napi_tx(vi, 0, vi->max_queue_pairs,
+ ec->tx_max_coalesced_frames);
if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
ret = virtnet_send_notf_coal_cmds(vi, ec);
@@ -3605,11 +3612,6 @@ static int virtnet_set_coalesce(struct net_device *dev,
if (ret)
return ret;
- if (update_napi) {
- for (; queue_number < vi->max_queue_pairs; queue_number++)
- vi->sq[queue_number].napi.weight = napi_weight;
- }
-
return ret;
}
@@ -3641,19 +3643,13 @@ static int virtnet_set_per_queue_coalesce(struct
net_device *dev,
struct ethtool_coalesce *ec)
{
struct virtnet_info *vi = netdev_priv(dev);
- int ret, napi_weight;
- bool update_napi = false;
+ int ret;
if (queue >= vi->max_queue_pairs)
return -EINVAL;
- /* Can't change NAPI weight if the link is up */
- napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
- ret = virtnet_should_update_vq_weight(dev->flags, napi_weight,
- vi->sq[queue].napi.weight,
- &update_napi);
- if (ret)
- return ret;
+ /* Param tx_frames can be used to switch napi_tx */
+ virtnet_switch_napi_tx(vi, queue, queue, ec->tx_max_coalesced_frames);
if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
ret = virtnet_send_notf_coal_vq_cmds(vi, ec, queue);
@@ -3663,9 +3659,6 @@ static int virtnet_set_per_queue_coalesce(struct
net_device *dev,
if (ret)
return ret;
- if (update_napi)
- vi->sq[queue].napi.weight = napi_weight;
-
return 0;
}
--
2.19.1.6.gb485710b
