[DCCP] ccid3: Finer-grained resolution of sending rates (1a21e49a) · Commits · e / devices / android_kernel_teracube_emerald

include/linux/tfrc.h

+6 −2

Original line number	Original line	Diff line number	Diff line
	@@ -37,10 +37,14 @@ struct tfrc_rx_info {
	* @tfrctx_p: current loss event rate (5.4)		* @tfrctx_p: current loss event rate (5.4)
	* @tfrctx_rto: estimate of RTO, equals 4*RTT (4.3)		* @tfrctx_rto: estimate of RTO, equals 4*RTT (4.3)
	* @tfrctx_ipi: inter-packet interval (4.6)		* @tfrctx_ipi: inter-packet interval (4.6)
			*
			* Note: X and X_recv are both maintained in units of 64 * bytes/second. This
			* enables a finer resolution of sending rates and avoids problems with
			* integer arithmetic; u32 is not sufficient as scaling consumes 6 bits.
	*/		*/
	struct tfrc_tx_info {		struct tfrc_tx_info {
	__u32 tfrctx_x;		__u64 tfrctx_x;
	__u32 tfrctx_x_recv;		__u64 tfrctx_x_recv;
	__u32 tfrctx_x_calc;		__u32 tfrctx_x_calc;
	__u32 tfrctx_rtt;		__u32 tfrctx_rtt;
	__u32 tfrctx_p;		__u32 tfrctx_p;

net/dccp/ccids/ccid3.c

+46 −30

Original line number	Original line	Diff line number	Diff line
	@@ -108,8 +108,9 @@ static inline void ccid3_update_send_time(struct ccid3_hc_tx_sock *hctx)
	{		{
	timeval_sub_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);		timeval_sub_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);

	/* Calculate new t_ipi (inter packet interval) by t_ipi = s / X_inst */		/* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
	hctx->ccid3hctx_t_ipi = usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_x);		hctx->ccid3hctx_t_ipi = scaled_div(hctx->ccid3hctx_s,
			hctx->ccid3hctx_x >> 6);

	/* Update nominal send time with regard to the new t_ipi */		/* Update nominal send time with regard to the new t_ipi */
	timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);		timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
	@@ -128,6 +129,10 @@ static inline void ccid3_update_send_time(struct ccid3_hc_tx_sock *hctx)
	* X = max(min(2 * X, 2 * X_recv), s / R);		* X = max(min(2 * X, 2 * X_recv), s / R);
	* tld = now;		* tld = now;
	*		*
			* Note: X and X_recv are both stored in units of 64 * bytes/second, to support
			* fine-grained resolution of sending rates. This requires scaling by 2^6
			* throughout the code. Only X_calc is unscaled (in bytes/second).
			*
	* If X has changed, we also update the scheduled send time t_now,		* If X has changed, we also update the scheduled send time t_now,
	* the inter-packet interval t_ipi, and the delta value.		* the inter-packet interval t_ipi, and the delta value.
	*/		*/
	@@ -135,18 +140,21 @@ static void ccid3_hc_tx_update_x(struct sock sk, struct timeval now)

	{		{
	struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);		struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
	const __u32 old_x = hctx->ccid3hctx_x;		const __u64 old_x = hctx->ccid3hctx_x;

	if (hctx->ccid3hctx_p > 0) {		if (hctx->ccid3hctx_p > 0) {
	hctx->ccid3hctx_x = max_t(u32, min(hctx->ccid3hctx_x_calc,
	hctx->ccid3hctx_x_recv * 2),		hctx->ccid3hctx_x = min_t(u64, hctx->ccid3hctx_x_calc << 6,
	hctx->ccid3hctx_s / TFRC_T_MBI);		hctx->ccid3hctx_x_recv * 2 );
			hctx->ccid3hctx_x = max_t(u64, hctx->ccid3hctx_x,
			(hctx->ccid3hctx_s << 6)/TFRC_T_MBI);

	} else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) >=		} else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) >=
	hctx->ccid3hctx_rtt) {		hctx->ccid3hctx_rtt) {
	hctx->ccid3hctx_x = max(min(hctx->ccid3hctx_x_recv,
	hctx->ccid3hctx_x ) * 2,		hctx->ccid3hctx_x = max(2 * min(hctx->ccid3hctx_x,
	usecs_div(hctx->ccid3hctx_s,		hctx->ccid3hctx_x_recv),
			scaled_div(hctx->ccid3hctx_s << 6,
	hctx->ccid3hctx_rtt ));		hctx->ccid3hctx_rtt ));
	hctx->ccid3hctx_t_ld = *now;		hctx->ccid3hctx_t_ld = *now;
	}		}
	@@ -194,13 +202,13 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
	case TFRC_SSTATE_NO_FBACK:		case TFRC_SSTATE_NO_FBACK:
	/* RFC 3448, 4.4: Halve send rate directly */		/* RFC 3448, 4.4: Halve send rate directly */
	hctx->ccid3hctx_x = max_t(u32, hctx->ccid3hctx_x / 2,		hctx->ccid3hctx_x = max_t(u32, hctx->ccid3hctx_x / 2,
	hctx->ccid3hctx_s / TFRC_T_MBI);		(hctx->ccid3hctx_s << 6)/TFRC_T_MBI);

	ccid3_pr_debug("%s, sk=%p, state=%s, updated tx rate to %d "		ccid3_pr_debug("%s, sk=%p, state=%s, updated tx rate to %u "
	"bytes/s\n",		"bytes/s\n",
	dccp_role(sk), sk,		dccp_role(sk), sk,
	ccid3_tx_state_name(hctx->ccid3hctx_state),		ccid3_tx_state_name(hctx->ccid3hctx_state),
	hctx->ccid3hctx_x);		(unsigned)(hctx->ccid3hctx_x >> 6));
	/* The value of R is still undefined and so we can not recompute		/* The value of R is still undefined and so we can not recompute
	* the timout value. Keep initial value as per [RFC 4342, 5]. */		* the timout value. Keep initial value as per [RFC 4342, 5]. */
	t_nfb = TFRC_INITIAL_TIMEOUT;		t_nfb = TFRC_INITIAL_TIMEOUT;
	@@ -209,11 +217,11 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
	case TFRC_SSTATE_FBACK:		case TFRC_SSTATE_FBACK:
	/*		/*
	* Check if IDLE since last timeout and recv rate is less than		* Check if IDLE since last timeout and recv rate is less than
	* 4 packets per RTT		* 4 packets (in units of 64*bytes/sec) per RTT
	*/		*/
	if (!hctx->ccid3hctx_idle \|\|		if (!hctx->ccid3hctx_idle \|\|
	(hctx->ccid3hctx_x_recv >=		(hctx->ccid3hctx_x_recv >= 4 *
	4 * usecs_div(hctx->ccid3hctx_s, hctx->ccid3hctx_rtt))) {		scaled_div(hctx->ccid3hctx_s << 6, hctx->ccid3hctx_rtt))) {
	struct timeval now;		struct timeval now;

	ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",		ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",
	@@ -227,17 +235,23 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
	* X_recv = max(X_recv / 2, s / (2 * t_mbi));		* X_recv = max(X_recv / 2, s / (2 * t_mbi));
	* Else		* Else
	* X_recv = X_calc / 4;		* X_recv = X_calc / 4;
			*
			* Note that X_recv is scaled by 2^6 while X_calc is not
	*/		*/
	BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);		BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);

	if (hctx->ccid3hctx_p == 0 \|\|		if (hctx->ccid3hctx_p == 0 \|\|
	hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv) {		hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5)) {
	hctx->ccid3hctx_x_recv = max_t(u32, hctx->ccid3hctx_x_recv / 2,
	hctx->ccid3hctx_s / (2 * TFRC_T_MBI));		hctx->ccid3hctx_x_recv =
			max_t(u64, hctx->ccid3hctx_x_recv / 2,
			(hctx->ccid3hctx_s << 6) /
			(2*TFRC_T_MBI));

	if (hctx->ccid3hctx_p == 0)		if (hctx->ccid3hctx_p == 0)
	dccp_timestamp(sk, &now);		dccp_timestamp(sk, &now);
	} else		} else
	hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc / 4;		hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc << 4;

	/* Now recalculate X [RFC 3448, 4.3, step (4)] */		/* Now recalculate X [RFC 3448, 4.3, step (4)] */
	ccid3_hc_tx_update_x(sk, &now);		ccid3_hc_tx_update_x(sk, &now);
	@@ -315,9 +329,9 @@ static int ccid3_hc_tx_send_packet(struct sock sk, struct sk_buff skb)
	hctx->ccid3hctx_t_last_win_count = now;		hctx->ccid3hctx_t_last_win_count = now;
	ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);

	/* Set initial sending rate to 1 packet per second */		/* Set initial sending rate X/s to 1pps (X is scaled by 2^6) */
	ccid3_hc_tx_update_s(hctx, skb->len);		ccid3_hc_tx_update_s(hctx, skb->len);
	hctx->ccid3hctx_x = hctx->ccid3hctx_s;		hctx->ccid3hctx_x = hctx->ccid3hctx_s << 6;

	/* First timeout, according to [RFC 3448, 4.2], is 1 second */		/* First timeout, according to [RFC 3448, 4.2], is 1 second */
	hctx->ccid3hctx_t_ipi = USEC_PER_SEC;		hctx->ccid3hctx_t_ipi = USEC_PER_SEC;
	@@ -438,8 +452,8 @@ static void ccid3_hc_tx_packet_recv(struct sock sk, struct sk_buff skb)
	return;		return;
	}		}

	/* Update receive rate */		/* Update receive rate in units of 64 * bytes/second */
	hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;		hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate << 6;

	/* Update loss event rate */		/* Update loss event rate */
	pinv = opt_recv->ccid3or_loss_event_rate;		pinv = opt_recv->ccid3or_loss_event_rate;
	@@ -475,12 +489,14 @@ static void ccid3_hc_tx_packet_recv(struct sock sk, struct sk_buff skb)
	* q is a constant, RFC 3448 recomments 0.9		* q is a constant, RFC 3448 recomments 0.9
	*/		*/
	if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {		if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
	/* Use Larger Initial Windows [RFC 4342, sec. 5]		/*
	* We deviate in that we use `s' instead of `MSS'. */		* Larger Initial Windows [RFC 4342, sec. 5]
			* We deviate in that we use `s' instead of `MSS'.
			*/
	u16 w_init = min( 4 * hctx->ccid3hctx_s,		u16 w_init = min( 4 * hctx->ccid3hctx_s,
	max(2 * hctx->ccid3hctx_s, 4380));		max(2 * hctx->ccid3hctx_s, 4380));
	hctx->ccid3hctx_rtt = r_sample;		hctx->ccid3hctx_rtt = r_sample;
	hctx->ccid3hctx_x = usecs_div(w_init, r_sample);		hctx->ccid3hctx_x = scaled_div(w_init<< 6, r_sample);
	hctx->ccid3hctx_t_ld = now;		hctx->ccid3hctx_t_ld = now;

	ccid3_update_send_time(hctx);		ccid3_update_send_time(hctx);
	@@ -488,7 +504,7 @@ static void ccid3_hc_tx_packet_recv(struct sock sk, struct sk_buff skb)
	ccid3_pr_debug("%s(%p), s=%u, w_init=%u, "		ccid3_pr_debug("%s(%p), s=%u, w_init=%u, "
	"R_sample=%ldus, X=%u\n", dccp_role(sk),		"R_sample=%ldus, X=%u\n", dccp_role(sk),
	sk, hctx->ccid3hctx_s, w_init, r_sample,		sk, hctx->ccid3hctx_s, w_init, r_sample,
	hctx->ccid3hctx_x);		(unsigned)(hctx->ccid3hctx_x >> 6));

	ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);		ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
	} else {		} else {
	@@ -508,7 +524,7 @@ static void ccid3_hc_tx_packet_recv(struct sock sk, struct sk_buff skb)
	sk, hctx->ccid3hctx_rtt, r_sample,		sk, hctx->ccid3hctx_rtt, r_sample,
	hctx->ccid3hctx_s, hctx->ccid3hctx_p,		hctx->ccid3hctx_s, hctx->ccid3hctx_p,
	hctx->ccid3hctx_x_calc,		hctx->ccid3hctx_x_calc,
	hctx->ccid3hctx_x);		(unsigned)(hctx->ccid3hctx_x >> 6));
	}		}

	/* unschedule no feedback timer */		/* unschedule no feedback timer */

net/dccp/ccids/ccid3.h

+26 −7

Original line number	Original line	Diff line number	Diff line
	@@ -75,14 +75,14 @@ enum ccid3_hc_tx_states {

	/** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket		/** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket
	*		*
	* @ccid3hctx_x - Current sending rate		* @ccid3hctx_x - Current sending rate in 64 * bytes per second
	* @ccid3hctx_x_recv - Receive rate		* @ccid3hctx_x_recv - Receive rate in 64 * bytes per second
	* @ccid3hctx_x_calc - Calculated send rate (RFC 3448, 3.1)		* @ccid3hctx_x_calc - Calculated rate in bytes per second
	* @ccid3hctx_rtt - Estimate of current round trip time in usecs		* @ccid3hctx_rtt - Estimate of current round trip time in usecs
	* @ccid3hctx_p - Current loss event rate (0-1) scaled by 1000000		* @ccid3hctx_p - Current loss event rate (0-1) scaled by 1000000
	* @ccid3hctx_s - Packet size		* @ccid3hctx_s - Packet size in bytes
	* @ccid3hctx_t_rto - Retransmission Timeout (RFC 3448, 3.1)		* @ccid3hctx_t_rto - Nofeedback Timer setting in usecs
	* @ccid3hctx_t_ipi - Interpacket (send) interval (RFC 3448, 4.6)		* @ccid3hctx_t_ipi - Interpacket (send) interval (RFC 3448, 4.6) in usecs
	* @ccid3hctx_state - Sender state, one of %ccid3_hc_tx_states		* @ccid3hctx_state - Sender state, one of %ccid3_hc_tx_states
	* @ccid3hctx_last_win_count - Last window counter sent		* @ccid3hctx_last_win_count - Last window counter sent
	* @ccid3hctx_t_last_win_count - Timestamp of earliest packet		* @ccid3hctx_t_last_win_count - Timestamp of earliest packet
	@@ -91,7 +91,7 @@ enum ccid3_hc_tx_states {
	* @ccid3hctx_idle - Flag indicating that sender is idling		* @ccid3hctx_idle - Flag indicating that sender is idling
	* @ccid3hctx_t_ld - Time last doubled during slow start		* @ccid3hctx_t_ld - Time last doubled during slow start
	* @ccid3hctx_t_nom - Nominal send time of next packet		* @ccid3hctx_t_nom - Nominal send time of next packet
	* @ccid3hctx_delta - Send timer delta		* @ccid3hctx_delta - Send timer delta (RFC 3448, 4.6) in usecs
	* @ccid3hctx_hist - Packet history		* @ccid3hctx_hist - Packet history
	* @ccid3hctx_options_received - Parsed set of retrieved options		* @ccid3hctx_options_received - Parsed set of retrieved options
	*/		*/
	@@ -171,4 +171,23 @@ static inline struct ccid3_hc_rx_sock ccid3_hc_rx_sk(const struct sock sk)
	return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);		return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
	}		}

			static inline u64 scaled_div(u64 a, u32 b)
			{
			BUG_ON(b==0);
			a *= 1000000;
			do_div(a, b);
			return a;
			}

			static inline u32 scaled_div32(u64 a, u32 b)
			{
			u64 result = scaled_div(a, b);

			if (result > UINT_MAX) {
			DCCP_CRIT("Overflow: a(%llu)/b(%u) > ~0U",
			(unsigned long long)a, b);
			return UINT_MAX;
			}
			return result;
			}
	#endif /* _DCCP_CCID3_H_ */		#endif /* _DCCP_CCID3_H_ */