diff options
author | Eric Dumazet <edumazet@google.com> | 2020-04-30 20:35:41 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2020-04-30 23:24:01 +0300 |
commit | 2b195850128f5bafde177b12489d9fa27962cc1e (patch) | |
tree | bbb5e20a0e2c8cb06bb28d316d89b7b821672cdc /net | |
parent | 3857c776240f0edef8639d7833626ab2ee7c7723 (diff) | |
download | linux-2b195850128f5bafde177b12489d9fa27962cc1e.tar.xz |
tcp: add tp->dup_ack_counter
In commit 86de5921a3d5 ("tcp: defer SACK compression after DupThresh")
I added a TCP_FASTRETRANS_THRESH bias to tp->compressed_ack in order
to enable sack compression only after 3 dupacks.
Since we plan to relax this rule for flows that involve
stacks not requiring this old rule, this patch adds
a distinct tp->dup_ack_counter.
This means the TCP_FASTRETRANS_THRESH value is now used
in a single location that a future patch can adjust:
if (tp->dup_ack_counter < TCP_FASTRETRANS_THRESH) {
tp->dup_ack_counter++;
goto send_now;
}
This patch also introduces tcp_sack_compress_send_ack()
helper to ease following patch comprehension.
This patch refines LINUX_MIB_TCPACKCOMPRESSED to not
count the acks that we had to send if the timer expires
or tcp_sack_compress_send_ack() is sending an ack.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/tcp_input.c | 36 | ||||
-rw-r--r-- | net/ipv4/tcp_output.c | 6 | ||||
-rw-r--r-- | net/ipv4/tcp_timer.c | 8 |
3 files changed, 37 insertions, 13 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index bf4ced9273e8..da777df0a0ba 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4327,6 +4327,27 @@ static void tcp_sack_maybe_coalesce(struct tcp_sock *tp) } } +static void tcp_sack_compress_send_ack(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (!tp->compressed_ack) + return; + + if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) + __sock_put(sk); + + /* Since we have to send one ack finally, + * substract one from tp->compressed_ack to keep + * LINUX_MIB_TCPACKCOMPRESSED accurate. + */ + NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, + tp->compressed_ack - 1); + + tp->compressed_ack = 0; + tcp_send_ack(sk); +} + static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq) { struct tcp_sock *tp = tcp_sk(sk); @@ -4355,8 +4376,7 @@ static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq) * If the sack array is full, forget about the last one. */ if (this_sack >= TCP_NUM_SACKS) { - if (tp->compressed_ack > TCP_FASTRETRANS_THRESH) - tcp_send_ack(sk); + tcp_sack_compress_send_ack(sk); this_sack--; tp->rx_opt.num_sacks--; sp--; @@ -5275,15 +5295,13 @@ send_now: if (tp->compressed_ack_rcv_nxt != tp->rcv_nxt) { tp->compressed_ack_rcv_nxt = tp->rcv_nxt; - if (tp->compressed_ack > TCP_FASTRETRANS_THRESH) - NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, - tp->compressed_ack - TCP_FASTRETRANS_THRESH); - tp->compressed_ack = 0; + tp->dup_ack_counter = 0; } - - if (++tp->compressed_ack <= TCP_FASTRETRANS_THRESH) + if (tp->dup_ack_counter < TCP_FASTRETRANS_THRESH) { + tp->dup_ack_counter++; goto send_now; - + } + tp->compressed_ack++; if (hrtimer_is_queued(&tp->compressed_ack_timer)) return; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index ba4482130f08..c414aeb1efa9 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -184,10 +184,10 @@ static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, { struct tcp_sock *tp = tcp_sk(sk); - if (unlikely(tp->compressed_ack > TCP_FASTRETRANS_THRESH)) { + if (unlikely(tp->compressed_ack)) { NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, - tp->compressed_ack - TCP_FASTRETRANS_THRESH); - tp->compressed_ack = TCP_FASTRETRANS_THRESH; + tp->compressed_ack); + tp->compressed_ack = 0; if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) __sock_put(sk); } diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index c3f26dcd6704..ada046f425d2 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -753,8 +753,14 @@ static enum hrtimer_restart tcp_compressed_ack_kick(struct hrtimer *timer) bh_lock_sock(sk); if (!sock_owned_by_user(sk)) { - if (tp->compressed_ack > TCP_FASTRETRANS_THRESH) + if (tp->compressed_ack) { + /* Since we have to send one ack finally, + * substract one from tp->compressed_ack to keep + * LINUX_MIB_TCPACKCOMPRESSED accurate. + */ + tp->compressed_ack--; tcp_send_ack(sk); + } } else { if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &sk->sk_tsq_flags)) |