From: Stephen Hemminger Date: Fri, 11 Nov 2005 01:09:53 +0000 (-0800) Subject: [TCP]: Appropriate Byte Count support X-Git-Tag: v2.6.15-rc1~20^2~3 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9772efb970780aeed488c19d8b4afd46c3b484af;p=linux-2.6 [TCP]: Appropriate Byte Count support This is an updated version of the RFC3465 ABC patch originally for Linux 2.6.11-rc4 by Yee-Ting Li. ABC is a way of counting bytes ack'd rather than packets when updating congestion control. The orignal ABC described in the RFC applied to a Reno style algorithm. For advanced congestion control there is little change after leaving slow start. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 65895bb514..ebc09a159f 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -78,6 +78,11 @@ inet_peer_gc_maxtime - INTEGER TCP variables: +tcp_abc - INTEGER + Controls Appropriate Byte Count defined in RFC3465. If set to + 0 then does congestion avoid once per ack. 1 is conservative + value, and 2 is more agressive. + tcp_syn_retries - INTEGER Number of times initial SYNs for an active TCP connection attempt will be retransmitted. Should not be higher than 255. Default value diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index 22cf5e1ac9..ab2791b318 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -390,6 +390,7 @@ enum NET_TCP_BIC_BETA=108, NET_IPV4_ICMP_ERRORS_USE_INBOUND_IFADDR=109, NET_TCP_CONG_CONTROL=110, + NET_TCP_ABC=111, }; enum { diff --git a/include/linux/tcp.h b/include/linux/tcp.h index ac4ca44c75..737b32e529 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -326,6 +326,7 @@ struct tcp_sock { __u32 snd_up; /* Urgent pointer */ __u32 total_retrans; /* Total retransmits for entire connection */ + __u32 bytes_acked; /* Appropriate Byte Counting - RFC3465 */ unsigned int keepalive_time; /* time before keep alive takes place */ unsigned int keepalive_intvl; /* time interval between keep alive probes */ diff --git a/include/net/tcp.h b/include/net/tcp.h index 54c3998862..44ba4a21cb 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -218,6 +218,7 @@ extern int sysctl_tcp_low_latency; 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 atomic_t tcp_memory_allocated; extern atomic_t tcp_sockets_allocated; @@ -770,6 +771,23 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk) */ static inline void tcp_slow_start(struct tcp_sock *tp) { + if (sysctl_tcp_abc) { + /* RFC3465: Slow Start + * 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 (tp->bytes_acked < tp->mss_cache) + return; + + /* We MAY increase by 2 if discovered delayed ack */ + if (sysctl_tcp_abc > 1 && tp->bytes_acked > 2*tp->mss_cache) { + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + } + } + tp->bytes_acked = 0; + if (tp->snd_cwnd < tp->snd_cwnd_clamp) tp->snd_cwnd++; } @@ -804,6 +822,7 @@ static inline void tcp_enter_cwr(struct sock *sk) 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) { __tcp_enter_cwr(sk); tcp_set_ca_state(sk, TCP_CA_CWR); diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 6526856235..01444a02b4 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -645,6 +645,14 @@ ctl_table ipv4_table[] = { .proc_handler = &proc_tcp_congestion_control, .strategy = &sysctl_tcp_congestion_control, }, + { + .ctl_name = NET_TCP_ABC, + .procname = "tcp_abc", + .data = &sysctl_tcp_abc, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, { .ctl_name = 0 } }; diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 72b7c22e1e..cfaf761337 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1669,6 +1669,7 @@ int tcp_disconnect(struct sock *sk, int flags) tp->packets_out = 0; tp->snd_ssthresh = 0x7fffffff; tp->snd_cwnd_cnt = 0; + tp->bytes_acked = 0; tcp_set_ca_state(sk, TCP_CA_Open); tcp_clear_retrans(tp); inet_csk_delack_init(sk); diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 6d3e883b48..c7cc62c8dc 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -192,17 +192,26 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight, /* In "safe" area, increase. */ if (tp->snd_cwnd <= tp->snd_ssthresh) tcp_slow_start(tp); - else { - /* In dangerous area, increase slowly. - * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd - */ - if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { - if (tp->snd_cwnd < tp->snd_cwnd_clamp) - tp->snd_cwnd++; - tp->snd_cwnd_cnt = 0; - } else - tp->snd_cwnd_cnt++; - } + + /* In dangerous area, increase slowly. */ + else if (sysctl_tcp_abc) { + /* RFC3465: Apppriate 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 { + /* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */ + if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + tp->snd_cwnd_cnt = 0; + } else + tp->snd_cwnd_cnt++; + } } EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index e430656549..4cb5e6f408 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -89,6 +89,7 @@ int sysctl_tcp_frto; int sysctl_tcp_nometrics_save; int sysctl_tcp_moderate_rcvbuf = 1; +int sysctl_tcp_abc = 1; #define FLAG_DATA 0x01 /* Incoming frame contained data. */ #define FLAG_WIN_UPDATE 0x02 /* Incoming ACK was a window update. */ @@ -1247,6 +1248,7 @@ 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(tp); /* Push undo marker, if it was plain RTO and nothing @@ -1904,6 +1906,7 @@ tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una, TCP_ECN_queue_cwr(tp); } + tp->bytes_acked = 0; tp->snd_cwnd_cnt = 0; tcp_set_ca_state(sk, TCP_CA_Recovery); } @@ -2310,6 +2313,9 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag) if (before(ack, prior_snd_una)) goto old_ack; + if (sysctl_tcp_abc && icsk->icsk_ca_state < TCP_CA_CWR) + tp->bytes_acked += ack - prior_snd_una; + if (!(flag&FLAG_SLOWPATH) && after(ack, prior_snd_una)) { /* Window is constant, pure forward advance. * No more checks are required. @@ -4370,6 +4376,7 @@ discard: EXPORT_SYMBOL(sysctl_tcp_ecn); EXPORT_SYMBOL(sysctl_tcp_reordering); +EXPORT_SYMBOL(sysctl_tcp_abc); EXPORT_SYMBOL(tcp_parse_options); EXPORT_SYMBOL(tcp_rcv_established); EXPORT_SYMBOL(tcp_rcv_state_process); diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index b1a63b2c6b..9203a21e29 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -380,6 +380,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req, */ newtp->snd_cwnd = 2; newtp->snd_cwnd_cnt = 0; + newtp->bytes_acked = 0; newtp->frto_counter = 0; newtp->frto_highmark = 0;