From f69ad292cfd13aa7ee00847320c6bb9ba2154e87 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 11 Jun 2015 09:15:18 -0700 Subject: [PATCH] tcp: fill shinfo->gso_size at last moment In commit cd7d8498c9a5 ("tcp: change tcp_skb_pcount() location") we stored gso_segs in a temporary cache hot location. This patch does the same for gso_size. This allows to save 2 cache line misses in tcp xmit path for the last packet that is considered but not sent because of various conditions (cwnd, tso defer, receiver window, TSQ...) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 13 ++++++++----- net/ipv4/tcp_input.c | 8 ++++---- net/ipv4/tcp_output.c | 12 ++++-------- 3 files changed, 16 insertions(+), 17 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 978cebedd3fc..950cfecaad3c 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -730,11 +730,14 @@ struct tcp_skb_cb { /* Note : tcp_tw_isn is used in input path only * (isn chosen by tcp_timewait_state_process()) * - * tcp_gso_segs is used in write queue only, - * cf tcp_skb_pcount() + * tcp_gso_segs/size are used in write queue only, + * cf tcp_skb_pcount()/tcp_skb_mss() */ __u32 tcp_tw_isn; - __u32 tcp_gso_segs; + struct { + u16 tcp_gso_segs; + u16 tcp_gso_size; + }; }; __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ @@ -790,10 +793,10 @@ static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) TCP_SKB_CB(skb)->tcp_gso_segs += segs; } -/* This is valid iff tcp_skb_pcount() > 1. */ +/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ static inline int tcp_skb_mss(const struct sk_buff *skb) { - return skb_shinfo(skb)->gso_size; + return TCP_SKB_CB(skb)->tcp_gso_size; } /* Events passed to congestion control interface */ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 70a6fa8ecbd3..684f095d196e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1316,12 +1316,12 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb, * code can come after this skb later on it's better to keep * setting gso_size to something. */ - if (!skb_shinfo(prev)->gso_size) - skb_shinfo(prev)->gso_size = mss; + if (!TCP_SKB_CB(prev)->tcp_gso_size) + TCP_SKB_CB(prev)->tcp_gso_size = mss; /* CHECKME: To clear or not to clear? Mimics normal skb currently */ if (tcp_skb_pcount(skb) <= 1) - skb_shinfo(skb)->gso_size = 0; + TCP_SKB_CB(skb)->tcp_gso_size = 0; /* Difference in this won't matter, both ACKed by the same cumul. ACK */ TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS); @@ -2248,7 +2248,7 @@ static void tcp_mark_head_lost(struct sock *sk, int packets, int mark_head) (oldcnt >= packets)) break; - mss = skb_shinfo(skb)->gso_size; + mss = tcp_skb_mss(skb); err = tcp_fragment(sk, skb, (packets - oldcnt) * mss, mss, GFP_ATOMIC); if (err < 0) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index d12888581337..787f57ff87c4 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -402,8 +402,6 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, */ static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) { - struct skb_shared_info *shinfo = skb_shinfo(skb); - skb->ip_summed = CHECKSUM_PARTIAL; skb->csum = 0; @@ -411,7 +409,6 @@ static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) TCP_SKB_CB(skb)->sacked = 0; tcp_skb_pcount_set(skb, 1); - shinfo->gso_size = 0; TCP_SKB_CB(skb)->seq = seq; if (flags & (TCPHDR_SYN | TCPHDR_FIN)) @@ -1028,8 +1025,9 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, tcp_skb_pcount(skb)); tp->segs_out += tcp_skb_pcount(skb); - /* OK, its time to fill skb_shinfo(skb)->gso_segs */ + /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); + skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); /* Our usage of tstamp should remain private */ skb->tstamp.tv64 = 0; @@ -1068,8 +1066,6 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) /* Initialize TSO segments for a packet. */ static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) { - struct skb_shared_info *shinfo = skb_shinfo(skb); - /* Make sure we own this skb before messing gso_size/gso_segs */ WARN_ON_ONCE(skb_cloned(skb)); @@ -1078,10 +1074,10 @@ static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) * non-TSO case. */ tcp_skb_pcount_set(skb, 1); - shinfo->gso_size = 0; + TCP_SKB_CB(skb)->tcp_gso_size = 0; } else { tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); - shinfo->gso_size = mss_now; + TCP_SKB_CB(skb)->tcp_gso_size = mss_now; } } -- GitLab