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tcp: remove Appropriate Byte Count support

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TCP Appropriate Byte Count was added by me, but later disabled.
There is no point in maintaining it since it is a potential source
of bugs and Linux already implements other better window protection
heuristics.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2013-02-05 07:25:17 +00:00 committed by David S. Miller
parent 547472b8e1
commit ca2eb5679f
9 changed files with 1 additions and 67 deletions
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11
Documentation/networking/ip-sysctl.txt
View File

@ -130,17 +130,6 @@ somaxconn - INTEGER
Defaults to 128. See also tcp_max_syn_backlog for additional tuning
for TCP sockets.
tcp_abc - INTEGER
Controls Appropriate Byte Count (ABC) defined in RFC3465.
ABC is a way of increasing congestion window (cwnd) more slowly
in response to partial acknowledgments.
Possible values are:
0 increase cwnd once per acknowledgment (no ABC)
1 increase cwnd once per acknowledgment of full sized segment
2 allow increase cwnd by two if acknowledgment is
of two segments to compensate for delayed acknowledgments.
Default: 0 (off)
tcp_abort_on_overflow - BOOLEAN
If listening service is too slow to accept new connections,
reset them. Default state is FALSE. It means that if overflow

1
include/linux/tcp.h
View File

@ -246,7 +246,6 @@ struct tcp_sock {
u32 sacked_out; /* SACK'd packets */
u32 fackets_out; /* FACK'd packets */
u32 tso_deferred;
u32 bytes_acked; /* Appropriate Byte Counting - RFC3465 */
/* from STCP, retrans queue hinting */
struct sk_buff* lost_skb_hint;

1
include/net/tcp.h
View File

@ -279,7 +279,6 @@ extern int sysctl_tcp_dma_copybreak;
extern int sysctl_tcp_nometrics_save;
extern int sysctl_tcp_moderate_rcvbuf;
extern int sysctl_tcp_tso_win_divisor;
extern int sysctl_tcp_abc;
extern int sysctl_tcp_mtu_probing;
extern int sysctl_tcp_base_mss;
extern int sysctl_tcp_workaround_signed_windows;

1
kernel/sysctl_binary.c
View File

@ -387,7 +387,6 @@ static const struct bin_table bin_net_ipv4_table[] = {
{ CTL_INT, NET_TCP_MODERATE_RCVBUF, "tcp_moderate_rcvbuf" },
{ CTL_INT, NET_TCP_TSO_WIN_DIVISOR, "tcp_tso_win_divisor" },
{ CTL_STR, NET_TCP_CONG_CONTROL, "tcp_congestion_control" },
{ CTL_INT, NET_TCP_ABC, "tcp_abc" },
{ CTL_INT, NET_TCP_MTU_PROBING, "tcp_mtu_probing" },
{ CTL_INT, NET_TCP_BASE_MSS, "tcp_base_mss" },
{ CTL_INT, NET_IPV4_TCP_WORKAROUND_SIGNED_WINDOWS, "tcp_workaround_signed_windows" },

7
net/ipv4/sysctl_net_ipv4.c
View File

@ -632,13 +632,6 @@ static struct ctl_table ipv4_table[] = {
.maxlen = TCP_CA_NAME_MAX,
.proc_handler = proc_tcp_congestion_control,
},
{
.procname = "tcp_abc",
.data = &sysctl_tcp_abc,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
.procname = "tcp_mtu_probing",
.data = &sysctl_tcp_mtu_probing,

1
net/ipv4/tcp.c
View File

@ -2289,7 +2289,6 @@ int tcp_disconnect(struct sock *sk, int flags)
tp->packets_out = 0;
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_cnt = 0;
tp->bytes_acked = 0;
tp->window_clamp = 0;
tcp_set_ca_state(sk, TCP_CA_Open);
tcp_clear_retrans(tp);

30
net/ipv4/tcp_cong.c
View File

@ -317,28 +317,11 @@ void tcp_slow_start(struct tcp_sock *tp)
snd_cwnd = 1U;
}
/* RFC3465: ABC Slow start
* Increase only after a full MSS of bytes is acked
*
* TCP sender SHOULD increase cwnd by the number of
* previously unacknowledged bytes ACKed by each incoming
* acknowledgment, provided the increase is not more than L
*/
if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache)
return;
if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh)
cnt = sysctl_tcp_max_ssthresh >> 1; /* limited slow start */
else
cnt = snd_cwnd; /* exponential increase */
/* RFC3465: ABC
* We MAY increase by 2 if discovered delayed ack
*/
if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache)
cnt <<= 1;
tp->bytes_acked = 0;
tp->snd_cwnd_cnt += cnt;
while (tp->snd_cwnd_cnt >= snd_cwnd) {
tp->snd_cwnd_cnt -= snd_cwnd;
@ -378,20 +361,9 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
/* In "safe" area, increase. */
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
/* In dangerous area, increase slowly. */
else if (sysctl_tcp_abc) {
/* RFC3465: Appropriate Byte Count
* increase once for each full cwnd acked
*/
if (tp->bytes_acked >= tp->snd_cwnd*tp->mss_cache) {
tp->bytes_acked -= tp->snd_cwnd*tp->mss_cache;
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
tp->snd_cwnd++;
}
} else {
else
tcp_cong_avoid_ai(tp, tp->snd_cwnd);
}
}
EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid);

15
net/ipv4/tcp_input.c
View File

@ -98,7 +98,6 @@ int sysctl_tcp_frto_response __read_mostly;
int sysctl_tcp_thin_dupack __read_mostly;
int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
int sysctl_tcp_abc __read_mostly;
int sysctl_tcp_early_retrans __read_mostly = 2;
#define FLAG_DATA 0x01 /* Incoming frame contained data. */
@ -2007,7 +2006,6 @@ static void tcp_enter_frto_loss(struct sock *sk, int allowed_segments, int flag)
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
tp->frto_counter = 0;
tp->bytes_acked = 0;
tp->reordering = min_t(unsigned int, tp->reordering,
sysctl_tcp_reordering);
@ -2056,7 +2054,6 @@ void tcp_enter_loss(struct sock *sk, int how)
tp->snd_cwnd_cnt = 0;
tp->snd_cwnd_stamp = tcp_time_stamp;
tp->bytes_acked = 0;
tcp_clear_retrans_partial(tp);
if (tcp_is_reno(tp))
@ -2684,7 +2681,6 @@ static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
struct tcp_sock *tp = tcp_sk(sk);
tp->high_seq = tp->snd_nxt;
tp->bytes_acked = 0;
tp->snd_cwnd_cnt = 0;
tp->prior_cwnd = tp->snd_cwnd;
tp->prr_delivered = 0;
@ -2735,7 +2731,6 @@ void tcp_enter_cwr(struct sock *sk, const int set_ssthresh)
struct tcp_sock *tp = tcp_sk(sk);
tp->prior_ssthresh = 0;
tp->bytes_acked = 0;
if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
tp->undo_marker = 0;
tcp_init_cwnd_reduction(sk, set_ssthresh);
@ -3417,7 +3412,6 @@ static void tcp_conservative_spur_to_response(struct tcp_sock *tp)
{
tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
tp->snd_cwnd_cnt = 0;
tp->bytes_acked = 0;
TCP_ECN_queue_cwr(tp);
tcp_moderate_cwnd(tp);
}
@ -3609,15 +3603,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (after(ack, prior_snd_una))
flag |= FLAG_SND_UNA_ADVANCED;
if (sysctl_tcp_abc) {
if (icsk->icsk_ca_state < TCP_CA_CWR)
tp->bytes_acked += ack - prior_snd_una;
else if (icsk->icsk_ca_state == TCP_CA_Loss)
/* we assume just one segment left network */
tp->bytes_acked += min(ack - prior_snd_una,
tp->mss_cache);
}
prior_fackets = tp->fackets_out;
prior_in_flight = tcp_packets_in_flight(tp);

1
net/ipv4/tcp_minisocks.c
View File

@ -446,7 +446,6 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
*/
newtp->snd_cwnd = TCP_INIT_CWND;
newtp->snd_cwnd_cnt = 0;
newtp->bytes_acked = 0;
newtp->frto_counter = 0;
newtp->frto_highmark = 0;