summaryrefslogtreecommitdiffstats
path: root/net
diff options
context:
space:
mode:
authorEric Dumazet <edumazet@google.com>2020-04-30 19:35:41 +0200
committerDavid S. Miller <davem@davemloft.net>2020-04-30 22:24:01 +0200
commit2b195850128f5bafde177b12489d9fa27962cc1e (patch)
treebbb5e20a0e2c8cb06bb28d316d89b7b821672cdc /net
parentMerge tag 'mlx5-updates-2020-04-30' of git://git.kernel.org/pub/scm/linux/ker... (diff)
downloadlinux-2b195850128f5bafde177b12489d9fa27962cc1e.tar.xz
linux-2b195850128f5bafde177b12489d9fa27962cc1e.zip
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.c36
-rw-r--r--net/ipv4/tcp_output.c6
-rw-r--r--net/ipv4/tcp_timer.c8
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))