* [PATCH] virtio_net: send notification coalescing command only if value changed
@ 2022-12-21 12:06 Alvaro Karsz
2022-12-21 12:33 ` Michael S. Tsirkin
0 siblings, 1 reply; 5+ messages in thread
From: Alvaro Karsz @ 2022-12-21 12:06 UTC (permalink / raw)
To: virtualization, netdev
Cc: Alvaro Karsz, Michael S. Tsirkin, Jason Wang, David S. Miller,
Eric Dumazet, Jakub Kicinski, Paolo Abeni
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>
---
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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] virtio_net: send notification coalescing command only if value changed
2022-12-21 12:06 [PATCH] virtio_net: send notification coalescing command only if value changed Alvaro Karsz
@ 2022-12-21 12:33 ` Michael S. Tsirkin
2022-12-21 12:44 ` Alvaro Karsz
0 siblings, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2022-12-21 12:33 UTC (permalink / raw)
To: Alvaro Karsz
Cc: virtualization, netdev, Jason Wang, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni
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 ...
> ---
> 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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] virtio_net: send notification coalescing command only if value changed
2022-12-21 12:33 ` Michael S. Tsirkin
@ 2022-12-21 12:44 ` Alvaro Karsz
2022-12-21 13:01 ` Michael S. Tsirkin
0 siblings, 1 reply; 5+ messages in thread
From: Alvaro Karsz @ 2022-12-21 12:44 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: virtualization, netdev, Jason Wang, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni
> Why do we bother? Resending needs more code and helps
> reliability ...
It just seems unnecessary.
If a user changes just one parameter:
$ ethtool -C <iface> tx-usecs 30
It will trigger 2 commands, including
VIRTIO_NET_CTRL_NOTF_COAL_RX_SET, even though no rx parameter changed.
If we'll add more ethtool coalescing parameters, changing one of the
new parameter will trigger meaningless
VIRTIO_NET_CTRL_NOTF_COAL_RX_SET and VIRTIO_NET_CTRL_NOTF_COAL_TX_SET
commands.
Alvaro
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] virtio_net: send notification coalescing command only if value changed
2022-12-21 12:44 ` Alvaro Karsz
@ 2022-12-21 13:01 ` Michael S. Tsirkin
2022-12-21 13:10 ` Alvaro Karsz
0 siblings, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2022-12-21 13:01 UTC (permalink / raw)
To: Alvaro Karsz
Cc: virtualization, netdev, Jason Wang, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni
On Wed, Dec 21, 2022 at 02:44:21PM +0200, Alvaro Karsz wrote:
> > Why do we bother? Resending needs more code and helps
> > reliability ...
>
> It just seems unnecessary.
> If a user changes just one parameter:
> $ ethtool -C <iface> tx-usecs 30
> It will trigger 2 commands, including
> VIRTIO_NET_CTRL_NOTF_COAL_RX_SET, even though no rx parameter changed.
>
> If we'll add more ethtool coalescing parameters, changing one of the
> new parameter will trigger meaningless
> VIRTIO_NET_CTRL_NOTF_COAL_RX_SET and VIRTIO_NET_CTRL_NOTF_COAL_TX_SET
> commands.
>
> Alvaro
We'll always just do 2 commands, right?
I don't think we should bother at this point.
It might not be completely redundant.
E.g. if a card lost the config resending it might help fix things.
--
MST
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] virtio_net: send notification coalescing command only if value changed
2022-12-21 13:01 ` Michael S. Tsirkin
@ 2022-12-21 13:10 ` Alvaro Karsz
0 siblings, 0 replies; 5+ messages in thread
From: Alvaro Karsz @ 2022-12-21 13:10 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: virtualization, netdev, Jason Wang, David S. Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni
> We'll always just do 2 commands, right?
This is my point, we are sending 2 commands at the moment, even though
one of them may be unnecessary.
> E.g. if a card lost the config resending it might help fix things.
How can it lose the config?
We can say the same about every command sent through the control vq.
> I don't think we should bother at this point.
Ok, I'll drop it.
Alvaro
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-12-21 13:11 UTC | newest]
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2022-12-21 12:06 [PATCH] virtio_net: send notification coalescing command only if value changed Alvaro Karsz
2022-12-21 12:33 ` Michael S. Tsirkin
2022-12-21 12:44 ` Alvaro Karsz
2022-12-21 13:01 ` Michael S. Tsirkin
2022-12-21 13:10 ` Alvaro Karsz
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