From 0f87230d1a6c253681550c6064715d06a32be73d Mon Sep 17 00:00:00 2001 From: Francis Yan Date: Sun, 27 Nov 2016 23:07:14 -0800 Subject: tcp: instrument how long TCP is busy sending This patch measures TCP busy time, which is defined as the period of time when sender has data (or FIN) to send. The time starts when data is buffered and stops when the write queue is flushed by ACKs or error events. Note the busy time does not include SYN time, unless data is included in SYN (i.e. Fast Open). It does include FIN time even if the FIN carries no payload. Excluding pure FIN is possible but would incur one additional test in the fast path, which may not be worth it. Signed-off-by: Francis Yan Signed-off-by: Yuchung Cheng Signed-off-by: Soheil Hassas Yeganeh Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- include/net/tcp.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/net/tcp.h b/include/net/tcp.h index e5ff4083870d..3e097e39d4d2 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1535,6 +1535,7 @@ static inline void tcp_write_queue_purge(struct sock *sk) { struct sk_buff *skb; + tcp_chrono_stop(sk, TCP_CHRONO_BUSY); while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) sk_wmem_free_skb(sk, skb); sk_mem_reclaim(sk); @@ -1593,8 +1594,10 @@ static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff * static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) { - if (sk->sk_send_head == skb_unlinked) + if (sk->sk_send_head == skb_unlinked) { sk->sk_send_head = NULL; + tcp_chrono_stop(sk, TCP_CHRONO_BUSY); + } if (tcp_sk(sk)->highest_sack == skb_unlinked) tcp_sk(sk)->highest_sack = NULL; } @@ -1616,6 +1619,7 @@ static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb /* Queue it, remembering where we must start sending. */ if (sk->sk_send_head == NULL) { sk->sk_send_head = skb; + tcp_chrono_start(sk, TCP_CHRONO_BUSY); if (tcp_sk(sk)->highest_sack == NULL) tcp_sk(sk)->highest_sack = skb; -- cgit v1.2.3