diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/Makefile | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 188 | ||||
| -rw-r--r-- | net/ipv4/tcp_metrics.c | 192 |
3 files changed, 195 insertions, 187 deletions
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile index ff75d3bbcd6a..5a23e8b37106 100644 --- a/net/ipv4/Makefile +++ b/net/ipv4/Makefile @@ -7,7 +7,7 @@ obj-y := route.o inetpeer.o protocol.o \ ip_output.o ip_sockglue.o inet_hashtables.o \ inet_timewait_sock.o inet_connection_sock.o \ tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \ - tcp_minisocks.o tcp_cong.o \ + tcp_minisocks.o tcp_cong.o tcp_metrics.o \ datagram.o raw.o udp.o udplite.o \ arp.o icmp.o devinet.o af_inet.o igmp.o \ fib_frontend.o fib_semantics.o fib_trie.o \ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ca0d0e7c9778..055ac49b8b40 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -93,7 +93,6 @@ int sysctl_tcp_rfc1337 __read_mostly; int sysctl_tcp_max_orphans __read_mostly = NR_FILE; int sysctl_tcp_frto __read_mostly = 2; int sysctl_tcp_frto_response __read_mostly; -int sysctl_tcp_nometrics_save __read_mostly; int sysctl_tcp_thin_dupack __read_mostly; @@ -701,7 +700,7 @@ static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt) /* Calculate rto without backoff. This is the second half of Van Jacobson's * routine referred to above. */ -static inline void tcp_set_rto(struct sock *sk) +void tcp_set_rto(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); /* Old crap is replaced with new one. 8) @@ -728,109 +727,6 @@ static inline void tcp_set_rto(struct sock *sk) tcp_bound_rto(sk); } -/* Save metrics learned by this TCP session. - This function is called only, when TCP finishes successfully - i.e. when it enters TIME-WAIT or goes from LAST-ACK to CLOSE. - */ -void tcp_update_metrics(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct dst_entry *dst = __sk_dst_get(sk); - - if (sysctl_tcp_nometrics_save) - return; - - if (dst && (dst->flags & DST_HOST)) { - const struct inet_connection_sock *icsk = inet_csk(sk); - int m; - unsigned long rtt; - - dst_confirm(dst); - - if (icsk->icsk_backoff || !tp->srtt) { - /* This session failed to estimate rtt. Why? - * Probably, no packets returned in time. - * Reset our results. - */ - if (!(dst_metric_locked(dst, RTAX_RTT))) - dst_metric_set(dst, RTAX_RTT, 0); - return; - } - - rtt = dst_metric_rtt(dst, RTAX_RTT); - m = rtt - tp->srtt; - - /* If newly calculated rtt larger than stored one, - * store new one. Otherwise, use EWMA. Remember, - * rtt overestimation is always better than underestimation. - */ - if (!(dst_metric_locked(dst, RTAX_RTT))) { - if (m <= 0) - set_dst_metric_rtt(dst, RTAX_RTT, tp->srtt); - else - set_dst_metric_rtt(dst, RTAX_RTT, rtt - (m >> 3)); - } - - if (!(dst_metric_locked(dst, RTAX_RTTVAR))) { - unsigned long var; - if (m < 0) - m = -m; - - /* Scale deviation to rttvar fixed point */ - m >>= 1; - if (m < tp->mdev) - m = tp->mdev; - - var = dst_metric_rtt(dst, RTAX_RTTVAR); - if (m >= var) - var = m; - else - var -= (var - m) >> 2; - - set_dst_metric_rtt(dst, RTAX_RTTVAR, var); - } - - if (tcp_in_initial_slowstart(tp)) { - /* Slow start still did not finish. */ - if (dst_metric(dst, RTAX_SSTHRESH) && - !dst_metric_locked(dst, RTAX_SSTHRESH) && - (tp->snd_cwnd >> 1) > dst_metric(dst, RTAX_SSTHRESH)) - dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_cwnd >> 1); - if (!dst_metric_locked(dst, RTAX_CWND) && - tp->snd_cwnd > dst_metric(dst, RTAX_CWND)) - dst_metric_set(dst, RTAX_CWND, tp->snd_cwnd); - } else if (tp->snd_cwnd > tp->snd_ssthresh && - icsk->icsk_ca_state == TCP_CA_Open) { - /* Cong. avoidance phase, cwnd is reliable. */ - if (!dst_metric_locked(dst, RTAX_SSTHRESH)) - dst_metric_set(dst, RTAX_SSTHRESH, - max(tp->snd_cwnd >> 1, tp->snd_ssthresh)); - if (!dst_metric_locked(dst, RTAX_CWND)) - dst_metric_set(dst, RTAX_CWND, - (dst_metric(dst, RTAX_CWND) + - tp->snd_cwnd) >> 1); - } else { - /* Else slow start did not finish, cwnd is non-sense, - ssthresh may be also invalid. - */ - if (!dst_metric_locked(dst, RTAX_CWND)) - dst_metric_set(dst, RTAX_CWND, - (dst_metric(dst, RTAX_CWND) + - tp->snd_ssthresh) >> 1); - if (dst_metric(dst, RTAX_SSTHRESH) && - !dst_metric_locked(dst, RTAX_SSTHRESH) && - tp->snd_ssthresh > dst_metric(dst, RTAX_SSTHRESH)) - dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_ssthresh); - } - - if (!dst_metric_locked(dst, RTAX_REORDERING)) { - if (dst_metric(dst, RTAX_REORDERING) < tp->reordering && - tp->reordering != sysctl_tcp_reordering) - dst_metric_set(dst, RTAX_REORDERING, tp->reordering); - } - } -} - __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst) { __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0); @@ -867,7 +763,7 @@ void tcp_enter_cwr(struct sock *sk, const int set_ssthresh) * Packet counting of FACK is based on in-order assumptions, therefore TCP * disables it when reordering is detected */ -static void tcp_disable_fack(struct tcp_sock *tp) +void tcp_disable_fack(struct tcp_sock *tp) { /* RFC3517 uses different metric in lost marker => reset on change */ if (tcp_is_fack(tp)) @@ -881,86 +777,6 @@ static void tcp_dsack_seen(struct tcp_sock *tp) tp->rx_opt.sack_ok |= TCP_DSACK_SEEN; } -/* Initialize metrics on socket. */ - -static void tcp_init_metrics(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct dst_entry *dst = __sk_dst_get(sk); - - if (dst == NULL) - goto reset; - - dst_confirm(dst); - - if (dst_metric_locked(dst, RTAX_CWND)) - tp->snd_cwnd_clamp = dst_metric(dst, RTAX_CWND); - if (dst_metric(dst, RTAX_SSTHRESH)) { - tp->snd_ssthresh = dst_metric(dst, RTAX_SSTHRESH); - if (tp->snd_ssthresh > tp->snd_cwnd_clamp) - tp->snd_ssthresh = tp->snd_cwnd_clamp; - } else { - /* ssthresh may have been reduced unnecessarily during. - * 3WHS. Restore it back to its initial default. - */ - tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; - } - if (dst_metric(dst, RTAX_REORDERING) && - tp->reordering != dst_metric(dst, RTAX_REORDERING)) { - tcp_disable_fack(tp); - tcp_disable_early_retrans(tp); - tp->reordering = dst_metric(dst, RTAX_REORDERING); - } - - if (dst_metric(dst, RTAX_RTT) == 0 || tp->srtt == 0) - goto reset; - - /* Initial rtt is determined from SYN,SYN-ACK. - * The segment is small and rtt may appear much - * less than real one. Use per-dst memory - * to make it more realistic. - * - * A bit of theory. RTT is time passed after "normal" sized packet - * is sent until it is ACKed. In normal circumstances sending small - * packets force peer to delay ACKs and calculation is correct too. - * The algorithm is adaptive and, provided we follow specs, it - * NEVER underestimate RTT. BUT! If peer tries to make some clever - * tricks sort of "quick acks" for time long enough to decrease RTT - * to low value, and then abruptly stops to do it and starts to delay - * ACKs, wait for troubles. - */ - if (dst_metric_rtt(dst, RTAX_RTT) > tp->srtt) { - tp->srtt = dst_metric_rtt(dst, RTAX_RTT); - tp->rtt_seq = tp->snd_nxt; - } - if (dst_metric_rtt(dst, RTAX_RTTVAR) > tp->mdev) { - tp->mdev = dst_metric_rtt(dst, RTAX_RTTVAR); - tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk)); - } - tcp_set_rto(sk); -reset: - if (tp->srtt == 0) { - /* RFC6298: 5.7 We've failed to get a valid RTT sample from - * 3WHS. This is most likely due to retransmission, - * including spurious one. Reset the RTO back to 3secs - * from the more aggressive 1sec to avoid more spurious - * retransmission. - */ - tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK; - inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK; - } - /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been - * retransmitted. In light of RFC6298 more aggressive 1sec - * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK - * retransmission has occurred. - */ - if (tp->total_retrans > 1) - tp->snd_cwnd = 1; - else - tp->snd_cwnd = tcp_init_cwnd(tp, dst); - tp->snd_cwnd_stamp = tcp_time_stamp; -} - static void tcp_update_reordering(struct sock *sk, const int metric, const int ts) { diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c new file mode 100644 index 000000000000..2793ecf928d3 --- /dev/null +++ b/net/ipv4/tcp_metrics.c @@ -0,0 +1,192 @@ +#include <linux/cache.h> +#include <linux/tcp.h> + +#include <net/inet_connection_sock.h> +#include <net/sock.h> +#include <net/dst.h> +#include <net/tcp.h> + +int sysctl_tcp_nometrics_save __read_mostly; + +/* Save metrics learned by this TCP session. This function is called + * only, when TCP finishes successfully i.e. when it enters TIME-WAIT + * or goes from LAST-ACK to CLOSE. + */ +void tcp_update_metrics(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct dst_entry *dst = __sk_dst_get(sk); + + if (sysctl_tcp_nometrics_save) + return; + + if (dst && (dst->flags & DST_HOST)) { + const struct inet_connection_sock *icsk = inet_csk(sk); + int m; + unsigned long rtt; + + dst_confirm(dst); + + if (icsk->icsk_backoff || !tp->srtt) { + /* This session failed to estimate rtt. Why? + * Probably, no packets returned in time. + * Reset our results. + */ + if (!(dst_metric_locked(dst, RTAX_RTT))) + dst_metric_set(dst, RTAX_RTT, 0); + return; + } + + rtt = dst_metric_rtt(dst, RTAX_RTT); + m = rtt - tp->srtt; + + /* If newly calculated rtt larger than stored one, + * store new one. Otherwise, use EWMA. Remember, + * rtt overestimation is always better than underestimation. + */ + if (!(dst_metric_locked(dst, RTAX_RTT))) { + if (m <= 0) + set_dst_metric_rtt(dst, RTAX_RTT, tp->srtt); + else + set_dst_metric_rtt(dst, RTAX_RTT, rtt - (m >> 3)); + } + + if (!(dst_metric_locked(dst, RTAX_RTTVAR))) { + unsigned long var; + if (m < 0) + m = -m; + + /* Scale deviation to rttvar fixed point */ + m >>= 1; + if (m < tp->mdev) + m = tp->mdev; + + var = dst_metric_rtt(dst, RTAX_RTTVAR); + if (m >= var) + var = m; + else + var -= (var - m) >> 2; + + set_dst_metric_rtt(dst, RTAX_RTTVAR, var); + } + + if (tcp_in_initial_slowstart(tp)) { + /* Slow start still did not finish. */ + if (dst_metric(dst, RTAX_SSTHRESH) && + !dst_metric_locked(dst, RTAX_SSTHRESH) && + (tp->snd_cwnd >> 1) > dst_metric(dst, RTAX_SSTHRESH)) + dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_cwnd >> 1); + if (!dst_metric_locked(dst, RTAX_CWND) && + tp->snd_cwnd > dst_metric(dst, RTAX_CWND)) + dst_metric_set(dst, RTAX_CWND, tp->snd_cwnd); + } else if (tp->snd_cwnd > tp->snd_ssthresh && + icsk->icsk_ca_state == TCP_CA_Open) { + /* Cong. avoidance phase, cwnd is reliable. */ + if (!dst_metric_locked(dst, RTAX_SSTHRESH)) + dst_metric_set(dst, RTAX_SSTHRESH, + max(tp->snd_cwnd >> 1, tp->snd_ssthresh)); + if (!dst_metric_locked(dst, RTAX_CWND)) + dst_metric_set(dst, RTAX_CWND, + (dst_metric(dst, RTAX_CWND) + + tp->snd_cwnd) >> 1); + } else { + /* Else slow start did not finish, cwnd is non-sense, + ssthresh may be also invalid. + */ + if (!dst_metric_locked(dst, RTAX_CWND)) + dst_metric_set(dst, RTAX_CWND, + (dst_metric(dst, RTAX_CWND) + + tp->snd_ssthresh) >> 1); + if (dst_metric(dst, RTAX_SSTHRESH) && + !dst_metric_locked(dst, RTAX_SSTHRESH) && + tp->snd_ssthresh > dst_metric(dst, RTAX_SSTHRESH)) + dst_metric_set(dst, RTAX_SSTHRESH, tp->snd_ssthresh); + } + + if (!dst_metric_locked(dst, RTAX_REORDERING)) { + if (dst_metric(dst, RTAX_REORDERING) < tp->reordering && + tp->reordering != sysctl_tcp_reordering) + dst_metric_set(dst, RTAX_REORDERING, tp->reordering); + } + } +} + +/* Initialize metrics on socket. */ + +void tcp_init_metrics(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct dst_entry *dst = __sk_dst_get(sk); + + if (dst == NULL) + goto reset; + + dst_confirm(dst); + + if (dst_metric_locked(dst, RTAX_CWND)) + tp->snd_cwnd_clamp = dst_metric(dst, RTAX_CWND); + if (dst_metric(dst, RTAX_SSTHRESH)) { + tp->snd_ssthresh = dst_metric(dst, RTAX_SSTHRESH); + if (tp->snd_ssthresh > tp->snd_cwnd_clamp) + tp->snd_ssthresh = tp->snd_cwnd_clamp; + } else { + /* ssthresh may have been reduced unnecessarily during. + * 3WHS. Restore it back to its initial default. + */ + tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; + } + if (dst_metric(dst, RTAX_REORDERING) && + tp->reordering != dst_metric(dst, RTAX_REORDERING)) { + tcp_disable_fack(tp); + tcp_disable_early_retrans(tp); + tp->reordering = dst_metric(dst, RTAX_REORDERING); + } + + if (dst_metric(dst, RTAX_RTT) == 0 || tp->srtt == 0) + goto reset; + + /* Initial rtt is determined from SYN,SYN-ACK. + * The segment is small and rtt may appear much + * less than real one. Use per-dst memory + * to make it more realistic. + * + * A bit of theory. RTT is time passed after "normal" sized packet + * is sent until it is ACKed. In normal circumstances sending small + * packets force peer to delay ACKs and calculation is correct too. + * The algorithm is adaptive and, provided we follow specs, it + * NEVER underestimate RTT. BUT! If peer tries to make some clever + * tricks sort of "quick acks" for time long enough to decrease RTT + * to low value, and then abruptly stops to do it and starts to delay + * ACKs, wait for troubles. + */ + if (dst_metric_rtt(dst, RTAX_RTT) > tp->srtt) { + tp->srtt = dst_metric_rtt(dst, RTAX_RTT); + tp->rtt_seq = tp->snd_nxt; + } + if (dst_metric_rtt(dst, RTAX_RTTVAR) > tp->mdev) { + tp->mdev = dst_metric_rtt(dst, RTAX_RTTVAR); + tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk)); + } + tcp_set_rto(sk); +reset: + if (tp->srtt == 0) { + /* RFC6298: 5.7 We've failed to get a valid RTT sample from + * 3WHS. This is most likely due to retransmission, + * including spurious one. Reset the RTO back to 3secs + * from the more aggressive 1sec to avoid more spurious + * retransmission. + */ + tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK; + inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK; + } + /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been + * retransmitted. In light of RFC6298 more aggressive 1sec + * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK + * retransmission has occurred. + */ + if (tp->total_retrans > 1) + tp->snd_cwnd = 1; + else + tp->snd_cwnd = tcp_init_cwnd(tp, dst); + tp->snd_cwnd_stamp = tcp_time_stamp; +} |