From: Mina Almasry
> Sent: 06 November 2023 02:44
>
> For device memory TCP, we expect the skb headers to be available in host
> memory for access, and we expect the skb frags to be in device memory
> and unaccessible to the host. We expect there to be no mixing and
> matching of device memory frags (unaccessible) with host memory frags
> (accessible) in the same skb.
>
> Add a skb->devmem flag which indicates whether the frags in this skb
> are device memory frags or not.
>
...
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 1fae276c1353..8fb468ff8115 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -805,6 +805,8 @@ typedef unsigned char *sk_buff_data_t;
> * @csum_level: indicates the number of consecutive checksums found in
> * the packet minus one that have been verified as
> * CHECKSUM_UNNECESSARY (max 3)
> + * @devmem: indicates that all the fragments in this skb are backed by
> + * device memory.
> * @dst_pending_confirm: need to confirm neighbour
> * @decrypted: Decrypted SKB
> * @slow_gro: state present at GRO time, slower prepare step required
> @@ -991,7 +993,7 @@ struct sk_buff {
> #if IS_ENABLED(CONFIG_IP_SCTP)
> __u8 csum_not_inet:1;
> #endif
> -
> + __u8 devmem:1;
> #if defined(CONFIG_NET_SCHED) || defined(CONFIG_NET_XGRESS)
> __u16 tc_index; /* traffic control index */
> #endif
> @@ -1766,6 +1768,12 @@ static inline void skb_zcopy_downgrade_managed(struct sk_buff *skb)
> __skb_zcopy_downgrade_managed(skb);
> }
Doesn't that bloat struct sk_buff?
I'm not sure there are any spare bits available.
Although CONFIG_NET_SWITCHDEV and CONFIG_NET_SCHED seem to
already add padding.
David
-
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