Re: [PATCH] virtio_net: send notification coalescing command only if value changed
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2022-12-21 12:34:15
Also in:
netdev
On Wed, Dec 21, 2022 at 02:06:18PM +0200, Alvaro Karsz wrote:
Don't send a VIRTIO_NET_CTRL_NOTF_COAL_TX_SET or VIRTIO_NET_CTRL_NOTF_COAL_RX_SET command if the coalescing parameters haven't changed. Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Why do we bother? Resending needs more code and helps reliability ...
quoted hunk ↗ jump to hunk
--- drivers/net/virtio_net.c | 48 ++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 21 deletions(-)diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 7723b2a49d8..1d7118de62a 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -2760,31 +2760,37 @@ static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi, struct virtio_net_ctrl_coal_tx coal_tx; struct virtio_net_ctrl_coal_rx coal_rx; - coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs); - coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames); - sg_init_one(&sgs_tx, &coal_tx, sizeof(coal_tx)); - - if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL, - VIRTIO_NET_CTRL_NOTF_COAL_TX_SET, - &sgs_tx)) - return -EINVAL; + if (ec->tx_coalesce_usecs != vi->tx_usecs || + ec->tx_max_coalesced_frames != vi->tx_max_packets) { + coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs); + coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames); + sg_init_one(&sgs_tx, &coal_tx, sizeof(coal_tx)); + + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL, + VIRTIO_NET_CTRL_NOTF_COAL_TX_SET, + &sgs_tx)) + return -EINVAL; - /* Save parameters */ - vi->tx_usecs = ec->tx_coalesce_usecs; - vi->tx_max_packets = ec->tx_max_coalesced_frames; + /* Save parameters */ + vi->tx_usecs = ec->tx_coalesce_usecs; + vi->tx_max_packets = ec->tx_max_coalesced_frames; + } - coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs); - coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames); - sg_init_one(&sgs_rx, &coal_rx, sizeof(coal_rx)); + if (ec->rx_coalesce_usecs != vi->rx_usecs || + ec->rx_max_coalesced_frames != vi->rx_max_packets) { + coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs); + coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames); + sg_init_one(&sgs_rx, &coal_rx, sizeof(coal_rx)); - if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL, - VIRTIO_NET_CTRL_NOTF_COAL_RX_SET, - &sgs_rx)) - return -EINVAL; + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL, + VIRTIO_NET_CTRL_NOTF_COAL_RX_SET, + &sgs_rx)) + return -EINVAL; - /* Save parameters */ - vi->rx_usecs = ec->rx_coalesce_usecs; - vi->rx_max_packets = ec->rx_max_coalesced_frames; + /* Save parameters */ + vi->rx_usecs = ec->rx_coalesce_usecs; + vi->rx_max_packets = ec->rx_max_coalesced_frames; + } return 0; }-- 2.32.0
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