[TCP]: Add TCP Hybla congestion control module. (835b3f0c) · Commits · e / devices / android_kernel_xiaomi_markw

net/ipv4/Kconfig

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		@@ -478,6 +478,16 @@ config TCP_CONG_HSTCP
		increase the congestion window by when an ACK is received.
		For more detail see http://www.icir.org/floyd/hstcp.html

		config TCP_CONG_HYBLA
		tristate "TCP-Hybla congestion control algorithm"
		depends on INET && EXPERIMENTAL
		default n
		---help---
		TCP-Hybla is a sender-side only change that eliminates penalization of
		long-RTT, large-bandwidth connections, like when satellite legs are
		involved, expecially when sharing a common bottleneck with normal
		terrestrial connections.

		endmenu

		source "net/ipv4/ipvs/Kconfig"

net/ipv4/Makefile

+1 −0

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		@@ -34,6 +34,7 @@ obj-$(CONFIG_IP_ROUTE_MULTIPATH_CACHED) += multipath.o
		obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
		obj-$(CONFIG_TCP_CONG_WESTWOOD) += tcp_westwood.o
		obj-$(CONFIG_TCP_CONG_HSTCP) += tcp_highspeed.o
		obj-$(CONFIG_TCP_CONG_HYBLA) += tcp_hybla.o

		obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
		xfrm4_output.o

net/ipv4/tcp_hybla.c

0 → 100644

+187 −0

Original line number	Diff line number	Diff line
		/*
		* TCP HYBLA
		*
		* TCP-HYBLA Congestion control algorithm, based on:
		* C.Caini, R.Firrincieli, "TCP-Hybla: A TCP Enhancement
		* for Heterogeneous Networks",
		* International Journal on satellite Communications,
		* September 2004
		* Daniele Lacamera
		* root at danielinux.net
		*/

		#include <linux/config.h>
		#include <linux/module.h>
		#include <net/tcp.h>

		/* Tcp Hybla structure. */
		struct hybla {
		u8 hybla_en;
		u32 snd_cwnd_cents; /* Keeps increment values when it is <1, <<7 */
		u32 rho; /* Rho parameter, integer part */
		u32 rho2; /* Rho * Rho, integer part */
		u32 rho_3ls; /* Rho parameter, <<3 */
		u32 rho2_7ls; /* Rho^2, <<7 */
		u32 minrtt; /* Minimum smoothed round trip time value seen */
		};

		/* Hybla reference round trip time (default= 1/40 sec = 25 ms),
		expressed in jiffies */
		static int rtt0 = 25;
		module_param(rtt0, int, 0644);
		MODULE_PARM_DESC(rtt0, "reference rout trip time (ms)");


		/* This is called to refresh values for hybla parameters */
		static inline void hybla_recalc_param (struct tcp_sock *tp)
		{
		struct hybla *ca = tcp_ca(tp);

		ca->rho_3ls = max_t(u32, tp->srtt / msecs_to_jiffies(rtt0), 8);
		ca->rho = ca->rho_3ls >> 3;
		ca->rho2_7ls = (ca->rho_3ls * ca->rho_3ls) << 1;
		ca->rho2 = ca->rho2_7ls >>7;
		}

		static void hybla_init(struct tcp_sock *tp)
		{
		struct hybla *ca = tcp_ca(tp);

		ca->rho = 0;
		ca->rho2 = 0;
		ca->rho_3ls = 0;
		ca->rho2_7ls = 0;
		ca->snd_cwnd_cents = 0;
		ca->hybla_en = 1;
		tp->snd_cwnd = 2;
		tp->snd_cwnd_clamp = 65535;

		/* 1st Rho measurement based on initial srtt */
		hybla_recalc_param(tp);

		/* set minimum rtt as this is the 1st ever seen */
		ca->minrtt = tp->srtt;
		tp->snd_cwnd = ca->rho;
		}

		static void hybla_state(struct tcp_sock *tp, u8 ca_state)
		{
		struct hybla *ca = tcp_ca(tp);

		ca->hybla_en = (ca_state == TCP_CA_Open);
		}

		static inline u32 hybla_fraction(u32 odds)
		{
		static const u32 fractions[] = {
		128, 139, 152, 165, 181, 197, 215, 234,
		};

		return (odds < ARRAY_SIZE(fractions)) ? fractions[odds] : 128;
		}

		/* TCP Hybla main routine.
		* This is the algorithm behavior:
		* o Recalc Hybla parameters if min_rtt has changed
		* o Give cwnd a new value based on the model proposed
		* o remember increments <1
		*/
		static void hybla_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
		u32 in_flight, int flag)
		{
		struct hybla *ca = tcp_ca(tp);
		u32 increment, odd, rho_fractions;
		int is_slowstart = 0;

		/* Recalculate rho only if this srtt is the lowest */
		if (tp->srtt < ca->minrtt){
		hybla_recalc_param(tp);
		ca->minrtt = tp->srtt;
		}

		if (!ca->hybla_en)
		return tcp_reno_cong_avoid(tp, ack, rtt, in_flight, flag);

		if (in_flight < tp->snd_cwnd)
		return;

		if (ca->rho == 0)
		hybla_recalc_param(tp);

		rho_fractions = ca->rho_3ls - (ca->rho << 3);

		if (tp->snd_cwnd < tp->snd_ssthresh) {
		/*
		* slow start
		* INC = 2^RHO - 1
		* This is done by splitting the rho parameter
		* into 2 parts: an integer part and a fraction part.
		* Inrement<<7 is estimated by doing:
		* [2^(int+fract)]<<7
		* that is equal to:
		* (2^int) * [(2^fract) <<7]
		* 2^int is straightly computed as 1<<int,
		* while we will use hybla_slowstart_fraction_increment() to
		* calculate 2^fract in a <<7 value.
		*/
		is_slowstart = 1;
		increment = ((1 << ca->rho) * hybla_fraction(rho_fractions))
		- 128;
		} else {
		/*
		* congestion avoidance
		* INC = RHO^2 / W
		* as long as increment is estimated as (rho<<7)/window
		* it already is <<7 and we can easily count its fractions.
		*/
		increment = ca->rho2_7ls / tp->snd_cwnd;
		if (increment < 128)
		tp->snd_cwnd_cnt++;
		}

		odd = increment % 128;
		tp->snd_cwnd += increment >> 7;
		ca->snd_cwnd_cents += odd;

		/* check when fractions goes >=128 and increase cwnd by 1. */
		while(ca->snd_cwnd_cents >= 128) {
		tp->snd_cwnd++;
		ca->snd_cwnd_cents -= 128;
		tp->snd_cwnd_cnt = 0;
		}

		/* clamp down slowstart cwnd to ssthresh value. */
		if (is_slowstart)
		tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);

		tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
		}

		static struct tcp_congestion_ops tcp_hybla = {
		.init = hybla_init,
		.ssthresh = tcp_reno_ssthresh,
		.min_cwnd = tcp_reno_min_cwnd,
		.cong_avoid = hybla_cong_avoid,
		.set_state = hybla_state,

		.owner = THIS_MODULE,
		.name = "hybla"
		};

		static int __init hybla_register(void)
		{
		BUG_ON(sizeof(struct hybla) > TCP_CA_PRIV_SIZE);
		return tcp_register_congestion_control(&tcp_hybla);
		}

		static void __exit hybla_unregister(void)
		{
		tcp_unregister_congestion_control(&tcp_hybla);
		}

		module_init(hybla_register);
		module_exit(hybla_unregister);

		MODULE_AUTHOR("Daniele Lacamera");
		MODULE_LICENSE("GPL");
		MODULE_DESCRIPTION("TCP Hybla");