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Commit 4aabd8ef authored by David S. Miller's avatar David S. Miller
Browse files

tcp: Move dynamnic metrics handling into seperate file. 



Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ad7eee98

include/net/tcp.h

+4 −0
Original line number Diff line number Diff line
@@ -388,6 +388,8 @@ extern void tcp_enter_frto(struct sock *sk); 
extern void tcp_enter_loss(struct sock *sk, int how);

extern void tcp_clear_retrans(struct tcp_sock *tp);

extern void tcp_update_metrics(struct sock *sk);

extern void tcp_init_metrics(struct sock *sk);

extern void tcp_disable_fack(struct tcp_sock *tp);

extern void tcp_close(struct sock *sk, long timeout);

extern void tcp_init_sock(struct sock *sk);

extern unsigned int tcp_poll(struct file * file, struct socket *sock,
@@ -556,6 +558,8 @@ static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 
	return (tp->srtt >> 3) + tp->rttvar;

}



extern void tcp_set_rto(struct sock *sk);



static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)

{

	tp->pred_flags = htonl((tp->tcp_header_len << 26) |

net/ipv4/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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 \

net/ipv4/tcp_input.c

+2 −186
Original line number Diff line number Diff line
@@ -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)

{

net/ipv4/tcp_metrics.c

0 → 100644
+192 −0
Original line number Diff line number Diff line 
#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;

}