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authorEric Dumazet <edumazet@google.com>2020-04-30 20:35:41 +0300
committerDavid S. Miller <davem@davemloft.net>2020-04-30 23:24:01 +0300
commit2b195850128f5bafde177b12489d9fa27962cc1e (patch)
treebbb5e20a0e2c8cb06bb28d316d89b7b821672cdc /net/ipv4/tcp_timer.c
parent3857c776240f0edef8639d7833626ab2ee7c7723 (diff)
downloadlinux-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/ipv4/tcp_timer.c')
-rw-r--r--net/ipv4/tcp_timer.c8
1 files changed, 7 insertions, 1 deletions
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))