Re: [PATCH net-next 3/5] netdev_features: convert NETIF_F_LLTX to dev->lltx
From: Eric Dumazet
Date: Tue Jun 25 2024 - 10:02:24 EST
On Tue, Jun 25, 2024 at 1:50 PM Alexander Lobakin
<aleksander.lobakin@xxxxxxxxx> wrote:
>
> NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
> rather an attribute, very similar to IFF_NO_QUEUE (and hot).
> Free one netdev_features_t bit and make it a private flag.
> Now the LLTX bit sits in the first ("Tx read-mostly") cacheline
> next to netdev_ops, so that the start_xmit locking code will
> potentially read 1 cacheline less, nice.
Are you sure ?
I certainly appreciate the data locality effort but
dev->features is read anyway in TX fast path from netif_skb_features()
Thanks.