Neal pointed out that non sack flows might suffer from ACK compression
added in the following patch ("tcp: implement coalescing on backlog queue")
Instead of tweaking tcp_add_backlog() we can take into
account how many ACK were coalesced, this information
will be available in skb_shinfo(skb)->gso_segs
Signed-off-by: Eric Dumazet
---
net/ipv4/tcp_input.c | 58 +---
1 file changed, 33 insertions(+), 25 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index
f32397890b6dcbc34976954c4be142108efa04d8..e5f3819ad859f6e6ca28e09c0f2dbdb7052708ee
100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1863,16 +1863,20 @@ static void tcp_check_reno_reordering(struct sock *sk,
const int addend)
/* Emulate SACKs for SACKless connection: account for a new dupack. */
-static void tcp_add_reno_sack(struct sock *sk)
+static void tcp_add_reno_sack(struct sock *sk, int num_dupack)
{
- struct tcp_sock *tp = tcp_sk(sk);
- u32 prior_sacked = tp->sacked_out;
+ if (num_dupack) {
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 prior_sacked = tp->sacked_out;
+ s32 delivered;
- tp->sacked_out++;
- tcp_check_reno_reordering(sk, 0);
- if (tp->sacked_out > prior_sacked)
- tp->delivered++; /* Some out-of-order packet is delivered */
- tcp_verify_left_out(tp);
+ tp->sacked_out += num_dupack;
+ tcp_check_reno_reordering(sk, 0);
+ delivered = tp->sacked_out - prior_sacked;
+ if (delivered > 0)
+ tp->delivered += delivered;
+ tcp_verify_left_out(tp);
+ }
}
/* Account for ACK, ACKing some data in Reno Recovery phase. */
@@ -2634,7 +2638,7 @@ void tcp_enter_recovery(struct sock *sk, bool ece_ack)
/* Process an ACK in CA_Loss state. Move to CA_Open if lost data are
* recovered or spurious. Otherwise retransmits more on partial ACKs.
*/
-static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack,
+static void tcp_process_loss(struct sock *sk, int flag, int num_dupack,
int *rexmit)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -2653,7 +2657,7 @@ static void tcp_process_loss(struct sock *sk, int flag,
bool is_dupack,
return;
if (after(tp->snd_nxt, tp->high_seq)) {
- if (flag & FLAG_DATA_SACKED || is_dupack)
+ if (flag & FLAG_DATA_SACKED || num_dupack)
tp->frto = 0; /* Step 3.a. loss was real */
} else if (flag & FLAG_SND_UNA_ADVANCED && !recovered) {
tp->high_seq = tp->snd_nxt;
@@ -2679,8 +2683,8 @@ static void tcp_process_loss(struct sock *sk, int flag,
bool is_dupack,
/* A Reno DUPACK means new data in F-RTO step 2.b above are
* delivered. Lower inflight to clock out (re)tranmissions.
*/
- if (after(tp->snd_nxt, tp->high_seq) && is_dupack)
- tcp_add_reno_sack(sk);
+ if (after(tp->snd_nxt, tp->high_seq) && num_dupack)
+ tcp_add_reno_sack(sk, num_dupack);
else if (flag & FLAG_SND_UNA_ADVANCED)
tcp_reset_reno_sack(tp);
}
@@ -2757,13 +2761,13 @@ static bool tcp_force_fast_retransmit(struct sock *sk)
* tcp_xmit_retransmit_queue().
*/
static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,
- bool is_dupack, int *ack_flag, int *rexmit)
+ int num_dupack, int *ack_flag, int *rexmit)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
int fast_rexmit = 0, flag = *ack_flag;
- bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
-tcp_force_fast_retransmit(sk));
+ bool do_lost = num_dupack || ((flag & FLAG_DATA_SACKED) &&
+ tcp_force_fast_retransmit(sk));
if (!tp->packets_out && tp->sacked_out)
tp->sacked_out = 0;
@@ -2810,8 +2814,8 @@ static void tcp_fastretrans_alert(struct sock *sk, const
u32 prior_snd_una,
switch (icsk->icsk_ca_state) {
case TCP_CA_Recovery:
if (!(flag & FLAG_SND_UNA_ADVANCED)) {
- if (tcp_is_reno(tp) && is_dupack)
- tcp_add_reno_sack(sk);
+ if (tcp_is_reno(tp))
+ tcp_add_reno_sack(sk, num_dupack);
} else {
if (tcp_try_undo_partial(sk, prior_snd_una))
return;
@@ -2826,7 +2830,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const
u32 prior_snd_una,
tcp_identify_packet_loss(sk, ack_flag);
br
