netdev - Re: [PATCH] bonding: don't force LACPDU tx to ~333 ms boundaries

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Message-ID: <1eeb3e3f-8acc-484b-b9c2-700516aa5cba@gmail.com>
Date: Wed, 25 Jun 2025 11:13:12 -0500
From: Carlos Bilbao <carlos.bilbao.osdev@...il.com>
To: "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>,
 Jay Vosburgh <jv@...sburgh.net>, 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>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 Carlos Bilbao <carlos.bilbao@...nel.org>,
 Tonghao Zhang <tonghao@...aicloud.com>
Subject: Re: [PATCH] bonding: don't force LACPDU tx to ~333 ms boundaries

Hello,

On 6/25/25 11:01, Seth Forshee (DigitalOcean) wrote:
> The timer which ensures that no more than 3 LACPDUs are transmitted in
> a second rearms itself every 333ms regardless of whether an LACPDU is
> transmitted when the timer expires. This causes LACPDU tx to be delayed
> until the next expiration of the timer, which effectively aligns LACPDUs
> to ~333ms boundaries. This results in a variable amount of jitter in the
> timing of periodic LACPDUs.
>
> Change this to only rearm the timer when an LACPDU is actually sent,
> allowing tx at any point after the timer has expired.
>
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
> ---
>   drivers/net/bonding/bond_3ad.c | 11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
> index c6807e473ab706afed9560bcdb5e6eca1934f5b7..a8d8aaa169fc09d7d5c201ff298b37b3f11a7ded 100644
> --- a/drivers/net/bonding/bond_3ad.c
> +++ b/drivers/net/bonding/bond_3ad.c
> @@ -1378,7 +1378,7 @@ static void ad_tx_machine(struct port *port)
>   	/* check if tx timer expired, to verify that we do not send more than
>   	 * 3 packets per second
>   	 */
> -	if (port->sm_tx_timer_counter && !(--port->sm_tx_timer_counter)) {
> +	if (!port->sm_tx_timer_counter || !(--port->sm_tx_timer_counter)) {
>   		/* check if there is something to send */
>   		if (port->ntt && (port->sm_vars & AD_PORT_LACP_ENABLED)) {
>   			__update_lacpdu_from_port(port);
> @@ -1393,12 +1393,13 @@ static void ad_tx_machine(struct port *port)
>   				 * again until demanded
>   				 */
>   				port->ntt = false;
> +
> +				/* restart tx timer(to verify that we will not
> +				 * exceed AD_MAX_TX_IN_SECOND
> +				 */
> +				port->sm_tx_timer_counter = ad_ticks_per_sec / AD_MAX_TX_IN_SECOND;
>   			}
>   		}
> -		/* restart tx timer(to verify that we will not exceed
> -		 * AD_MAX_TX_IN_SECOND
> -		 */
> -		port->sm_tx_timer_counter = ad_ticks_per_sec/AD_MAX_TX_IN_SECOND;
>   	}
>   }


Reviewed-by: Carlos Bilbao <carlos.bilbao@...nel.org>


>   
>
> ---
> base-commit: 86731a2a651e58953fc949573895f2fa6d456841
> change-id: 20250625-fix-lacpdu-jitter-1554d9f600ab
>
> Best regards,


Thanks,

Carlos