Re: [PATCH net-next] net: ethtool: add COALESCE_RX_CQE_FRAMES/NSECS parameters

[Tariq Toukan <ttoukan.linux@gmail.com>]

On 22/02/2026 23:23, Haiyang Zhang wrote:
> From: Haiyang Zhang <haiyangz@microsoft.com>
> 
> Add two parameters for drivers supporting Rx CQE Coalescing.
> 
> ETHTOOL_A_COALESCE_RX_CQE_FRAMES:
> Maximum number of frames that can be coalesced into a CQE.
> 
> ETHTOOL_A_COALESCE_RX_CQE_NSECS:
> Time out value in nanoseconds after the first packet arrival in a
> coalesced CQE to be sent.
> 
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>   Documentation/netlink/specs/ethtool.yaml       |  8 ++++++++
>   Documentation/networking/ethtool-netlink.rst   | 10 ++++++++++
>   include/linux/ethtool.h                        |  6 +++++-
>   include/uapi/linux/ethtool_netlink_generated.h |  2 ++
>   net/ethtool/coalesce.c                         | 14 +++++++++++++-
>   5 files changed, 38 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
> index 0a2d2343f79a..951d98f6bb12 100644
> --- a/Documentation/netlink/specs/ethtool.yaml
> +++ b/Documentation/netlink/specs/ethtool.yaml
> @@ -861,6 +861,12 @@ attribute-sets:
>           name: tx-profile
>           type: nest
>           nested-attributes: profile
> +      -
> +        name: rx-cqe-frames
> +        type: u32
> +      -
> +        name: rx-cqe-nsecs
> +        type: u32
>   
>     -
>       name: pause-stat
> @@ -2244,6 +2250,8 @@ operations:
>               - tx-aggr-time-usecs
>               - rx-profile
>               - tx-profile
> +            - rx-cqe-frames
> +            - rx-cqe-nsecs
>         dump: *coalesce-get-op
>       -
>         name: coalesce-set
> diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
> index af56c304cef4..a3e78b69fd07 100644
> --- a/Documentation/networking/ethtool-netlink.rst
> +++ b/Documentation/networking/ethtool-netlink.rst
> @@ -1072,6 +1072,8 @@ Kernel response contents:
>     ``ETHTOOL_A_COALESCE_TX_AGGR_TIME_USECS``    u32     time (us), aggr, Tx
>     ``ETHTOOL_A_COALESCE_RX_PROFILE``            nested  profile of DIM, Rx
>     ``ETHTOOL_A_COALESCE_TX_PROFILE``            nested  profile of DIM, Tx
> +  ``ETHTOOL_A_COALESCE_RX_CQE_FRAMES``         u32     max packets, Rx CQE
> +  ``ETHTOOL_A_COALESCE_RX_CQE_NSECS``          u32     delay (ns), Rx CQE
>     ===========================================  ======  =======================
>   
>   Attributes are only included in reply if their value is not zero or the
> @@ -1105,6 +1107,12 @@ well with frequent small-sized URBs transmissions.
>   to DIM parameters, see `Generic Network Dynamic Interrupt Moderation (Net DIM)
>   <https://www.kernel.org/doc/Documentation/networking/net_dim.rst>`_.
>   
> +Rx CQE coalescing allows multiple received packets to be coalesced into a single
> +Completion Queue Entry (CQE). ``ETHTOOL_A_COALESCE_RX_CQE_FRAMES`` describes the
> +maximum number of frames that can be coalesced into a CQE.
> +``ETHTOOL_A_COALESCE_RX_CQE_NSECS`` describes max time in nanoseconds after the
> +first packet arrival in a coalesced CQE to be sent.
> +

I am trying to understand how generic this feature/API is.
Can you please elaborate on the feature you want to configure here?

A single CQE to describe several packets?
What is the price? What per-packet information/hw offloads do you lose 
in the process?

For comparison, in mlx5 we have RX CQE compression, which can be applied 
on multiple near-identical completions that share/match several fields. 
Still, there is a per-packet mini-cqe with distinctive per-packet fields 
like csum.

>   COALESCE_SET
>   ============
>   
> @@ -1143,6 +1151,8 @@ Request contents:
>     ``ETHTOOL_A_COALESCE_TX_AGGR_TIME_USECS``    u32     time (us), aggr, Tx
>     ``ETHTOOL_A_COALESCE_RX_PROFILE``            nested  profile of DIM, Rx
>     ``ETHTOOL_A_COALESCE_TX_PROFILE``            nested  profile of DIM, Tx
> +  ``ETHTOOL_A_COALESCE_RX_CQE_FRAMES``         u32     max packets, Rx CQE
> +  ``ETHTOOL_A_COALESCE_RX_CQE_NSECS``          u32     delay (ns), Rx CQE
>     ===========================================  ======  =======================
>   
>   Request is rejected if it attributes declared as unsupported by driver (i.e.
> diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
> index 798abec67a1b..25ccd2d5d4dc 100644
> --- a/include/linux/ethtool.h
> +++ b/include/linux/ethtool.h
> @@ -332,6 +332,8 @@ struct kernel_ethtool_coalesce {
>   	u32 tx_aggr_max_bytes;
>   	u32 tx_aggr_max_frames;
>   	u32 tx_aggr_time_usecs;
> +	u32 rx_cqe_frames;
> +	u32 rx_cqe_nsecs;
>   };
>   
>   /**
> @@ -380,7 +382,9 @@ bool ethtool_convert_link_mode_to_legacy_u32(u32 *legacy_u32,
>   #define ETHTOOL_COALESCE_TX_AGGR_TIME_USECS	BIT(26)
>   #define ETHTOOL_COALESCE_RX_PROFILE		BIT(27)
>   #define ETHTOOL_COALESCE_TX_PROFILE		BIT(28)
> -#define ETHTOOL_COALESCE_ALL_PARAMS		GENMASK(28, 0)
> +#define ETHTOOL_COALESCE_RX_CQE_FRAMES		BIT(29)
> +#define ETHTOOL_COALESCE_RX_CQE_NSECS		BIT(30)
> +#define ETHTOOL_COALESCE_ALL_PARAMS		GENMASK(30, 0)
>   
>   #define ETHTOOL_COALESCE_USECS						\
>   	(ETHTOOL_COALESCE_RX_USECS | ETHTOOL_COALESCE_TX_USECS)
> diff --git a/include/uapi/linux/ethtool_netlink_generated.h b/include/uapi/linux/ethtool_netlink_generated.h
> index 556a0c834df5..efc6e4ade77b 100644
> --- a/include/uapi/linux/ethtool_netlink_generated.h
> +++ b/include/uapi/linux/ethtool_netlink_generated.h
> @@ -371,6 +371,8 @@ enum {
>   	ETHTOOL_A_COALESCE_TX_AGGR_TIME_USECS,
>   	ETHTOOL_A_COALESCE_RX_PROFILE,
>   	ETHTOOL_A_COALESCE_TX_PROFILE,
> +	ETHTOOL_A_COALESCE_RX_CQE_FRAMES,
> +	ETHTOOL_A_COALESCE_RX_CQE_NSECS,
>   
>   	__ETHTOOL_A_COALESCE_CNT,
>   	ETHTOOL_A_COALESCE_MAX = (__ETHTOOL_A_COALESCE_CNT - 1)
> diff --git a/net/ethtool/coalesce.c b/net/ethtool/coalesce.c
> index 3e18ca1ccc5e..349bb02c517a 100644
> --- a/net/ethtool/coalesce.c
> +++ b/net/ethtool/coalesce.c
> @@ -118,6 +118,8 @@ static int coalesce_reply_size(const struct ethnl_req_info *req_base,
>   	       nla_total_size(sizeof(u32)) +	/* _TX_AGGR_MAX_BYTES */
>   	       nla_total_size(sizeof(u32)) +	/* _TX_AGGR_MAX_FRAMES */
>   	       nla_total_size(sizeof(u32)) +	/* _TX_AGGR_TIME_USECS */
> +	       nla_total_size(sizeof(u32)) +	/* _RX_CQE_FRAMES */
> +	       nla_total_size(sizeof(u32)) +	/* _RX_CQE_NSECS */
>   	       total_modersz * 2;		/* _{R,T}X_PROFILE */
>   }
>   
> @@ -269,7 +271,11 @@ static int coalesce_fill_reply(struct sk_buff *skb,
>   	    coalesce_put_u32(skb, ETHTOOL_A_COALESCE_TX_AGGR_MAX_FRAMES,
>   			     kcoal->tx_aggr_max_frames, supported) ||
>   	    coalesce_put_u32(skb, ETHTOOL_A_COALESCE_TX_AGGR_TIME_USECS,
> -			     kcoal->tx_aggr_time_usecs, supported))
> +			     kcoal->tx_aggr_time_usecs, supported) ||
> +	    coalesce_put_u32(skb, ETHTOOL_A_COALESCE_RX_CQE_FRAMES,
> +			     kcoal->rx_cqe_frames, supported) ||
> +	    coalesce_put_u32(skb, ETHTOOL_A_COALESCE_RX_CQE_NSECS,
> +			     kcoal->rx_cqe_nsecs, supported))
>   		return -EMSGSIZE;
>   
>   	if (!req_base->dev || !req_base->dev->irq_moder)
> @@ -338,6 +344,8 @@ const struct nla_policy ethnl_coalesce_set_policy[] = {
>   	[ETHTOOL_A_COALESCE_TX_AGGR_MAX_BYTES] = { .type = NLA_U32 },
>   	[ETHTOOL_A_COALESCE_TX_AGGR_MAX_FRAMES] = { .type = NLA_U32 },
>   	[ETHTOOL_A_COALESCE_TX_AGGR_TIME_USECS] = { .type = NLA_U32 },
> +	[ETHTOOL_A_COALESCE_RX_CQE_FRAMES] = { .type = NLA_U32 },
> +	[ETHTOOL_A_COALESCE_RX_CQE_NSECS] = { .type = NLA_U32 },
>   	[ETHTOOL_A_COALESCE_RX_PROFILE] =
>   		NLA_POLICY_NESTED(coalesce_profile_policy),
>   	[ETHTOOL_A_COALESCE_TX_PROFILE] =
> @@ -570,6 +578,10 @@ __ethnl_set_coalesce(struct ethnl_req_info *req_info, struct genl_info *info,
>   			 tb[ETHTOOL_A_COALESCE_TX_AGGR_MAX_FRAMES], &mod);
>   	ethnl_update_u32(&kernel_coalesce.tx_aggr_time_usecs,
>   			 tb[ETHTOOL_A_COALESCE_TX_AGGR_TIME_USECS], &mod);
> +	ethnl_update_u32(&kernel_coalesce.rx_cqe_frames,
> +			 tb[ETHTOOL_A_COALESCE_RX_CQE_FRAMES], &mod);
> +	ethnl_update_u32(&kernel_coalesce.rx_cqe_nsecs,
> +			 tb[ETHTOOL_A_COALESCE_RX_CQE_NSECS], &mod);
>   
>   	if (dev->irq_moder && dev->irq_moder->profile_flags & DIM_PROFILE_RX) {
>   		ret = ethnl_update_profile(dev, &dev->irq_moder->rx_profile,