linux-kernel - Re: [PATCH RFC 1/2] net: mana: Add support for coalesced RX packets on CQE

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Message-ID: <20260105114929.GA330625@horms.kernel.org>
Date: Mon, 5 Jan 2026 11:49:29 +0000
From: Simon Horman <horms@...nel.org>
To: Haiyang Zhang <haiyangz@...ux.microsoft.com>
Cc: linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	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>,
	Long Li <longli@...rosoft.com>,
	Konstantin Taranov <kotaranov@...rosoft.com>,
	Erni Sri Satya Vennela <ernis@...ux.microsoft.com>,
	Shradha Gupta <shradhagupta@...ux.microsoft.com>,
	Saurabh Sengar <ssengar@...ux.microsoft.com>,
	Aditya Garg <gargaditya@...ux.microsoft.com>,
	Dipayaan Roy <dipayanroy@...ux.microsoft.com>,
	Shiraz Saleem <shirazsaleem@...rosoft.com>,
	linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
	paulros@...rosoft.com
Subject: Re: [PATCH RFC 1/2] net: mana: Add support for coalesced RX packets
 on CQE

On Tue, Dec 16, 2025 at 07:57:54AM -0800, Haiyang Zhang wrote:
> From: Haiyang Zhang <haiyangz@...rosoft.com>
> 
> Our NIC can have up to 4 RX packets on 1 CQE. To support this feature,
> check and process the type CQE_RX_COALESCED_4. The default setting is
> disabled, to avoid possible regression on latency.
> 
> And add ethtool handler to switch this feature. To turn it on, run:
>   ethtool -C <nic> rx-frames 4
> To turn it off:
>   ethtool -C <nic> rx-frames 1
> 
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>

...

> diff --git a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
> index 0e2f4343ac67..1b9ed5c9bbff 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
> @@ -397,6 +397,58 @@ static void mana_get_channels(struct net_device *ndev,
>  	channel->combined_count = apc->num_queues;
>  }
>  
> +static int mana_get_coalesce(struct net_device *ndev,
> +			     struct ethtool_coalesce *ec,
> +			     struct kernel_ethtool_coalesce *kernel_coal,
> +			     struct netlink_ext_ack *extack)

...

> +	if (err) {
> +		netdev_err(ndev, "Set rx-frames to %u failed:%d\n",
> +			   ec->rx_max_coalesced_frames, err);
> +		NL_SET_ERR_MSG_FMT(extack, "Set rx-frames to %u failed:%d\n",
> +				   ec->rx_max_coalesced_frames, err);

nit: I don't think the trailing '\n' is necessary here.

     Flagged by coccinelle.

> +
> +		apc->cqe_coalescing_enable = saved_cqe_coalescing_enable;
> +	}
> +
> +	return err;
> +}

...