Hi,
Lawrence Brakmo wrote:
> Based on comments by Neal Cardwell to tcp_nv patch:
>
> AFAICT this patch would not require an increase in the size of sk_buff
> cb[] if it were to take advantage of the fact that the tcp_skb_cb
> header.h4 and header.h6 fields are only used in the packet reception
> code path, and this in_flight field is only used on the transmit
> side. So the in_flight field could be placed in a struct that is
> itself placed in a union with the "header" union.
Please make another patch only for this.
>
> That way the sender code can remember the in_flight value
> without requiring any extra space. And in the future other
> sender-side info could be stored in the "tx" struct, if needed.
>
> Signed-off-by: Lawrence Brakmo <bra...@fb.com>
> ---
> include/net/tcp.h | 13 ++++++++++---
> net/ipv4/tcp_input.c | 5 ++++-
> net/ipv4/tcp_output.c | 4 +++-
> 3 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 1e6c5b04..b98d79a 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -755,11 +755,17 @@ struct tcp_skb_cb {
> /* 1 byte hole */
> __u32 ack_seq; /* Sequence number ACK'd */
> union {
> - struct inet_skb_parm h4;
> + struct {
> + /* bytes in flight when this packet was sent */
> + __u32 in_flight;
> + } tx; /* only used for outgoing skbs */
> + union {
> + struct inet_skb_parm h4;
> #if IS_ENABLED(CONFIG_IPV6)
> - struct inet6_skb_parm h6;
> + struct inet6_skb_parm h6;
> #endif
> - } header; /* For incoming frames */
> + } header; /* For incoming skbs */
> + };
> };
>
> #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
> @@ -837,6 +843,7 @@ union tcp_cc_info;
> struct ack_sample {
> u32 pkts_acked;
> s32 rtt_us;
> + u32 in_flight;
> };
>
> struct tcp_congestion_ops {
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 423d3af..3ab4178 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -3068,6 +3068,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int
> prior_fackets,
> long ca_rtt_us = -1L;
> struct sk_buff *skb;
> u32 pkts_acked = 0;
> + u32 last_in_flight = 0;
> bool rtt_update;
> int flag = 0;
>
> @@ -3107,6 +3108,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int
> prior_fackets,
> if (!first_ackt.v64)
> first_ackt = last_ackt;
>
> + last_in_flight = TCP_SKB_CB(skb)->tx.in_flight;
> reord = min(pkts_acked, reord);
> if (!after(scb->end_seq, tp->high_seq))
> flag |= FLAG_ORIG_SACK_ACKED;
> @@ -3196,7 +3198,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, int
> prior_fackets,
> }
>
> if (icsk->icsk_ca_ops->pkts_acked) {
> - struct ack_sample sample = {pkts_acked, ca_rtt_us};
> + struct ack_sample sample = {pkts_acked, ca_rtt_us,
> + last_in_flight};
>
> icsk->icsk_ca_ops->pkts_acked(sk, &sample);
> }
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 7105784..e9deab5 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -920,9 +920,12 @@ static int tcp_transmit_skb(struct sock *sk, struct
> sk_buff *skb, int clone_it,
> int err;
>
> BUG_ON(!skb || !tcp_skb_pcount(skb));
> + tp = tcp_sk(sk);
>
> if (clone_it) {
> skb_mstamp_get(&skb->skb_mstamp);
> + TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq
> + - tp->snd_una;
>
> if (unlikely(skb_cloned(skb)))
> skb = pskb_copy(skb, gfp_mask);
> @@ -933,7 +936,6 @@ static int tcp_transmit_skb(struct sock *sk, struct
> sk_buff *skb, int clone_it,
> }
>
> inet = inet_sk(sk);
> - tp = tcp_sk(sk);
> tcb = TCP_SKB_CB(skb);
> memset(&opts, 0, sizeof(opts));
>
>
--
吉藤英明 <hideaki.yoshif...@miraclelinux.com>
ミラクル・リナックス株式会社 技術本部 サポート部
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