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cc.c
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cc.h
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cc_cdg.c
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cc_chd.c
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cc_cubic.c
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cc_cubic.h
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cc_dctcp.c
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cc_hd.c
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cc_htcp.c
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cc_module.h
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cc_newreno.c
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cc_newreno.h
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cc_vegas.c
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Editing: cc_cubic.h
/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2008-2010 Lawrence Stewart <lstewart@freebsd.org> * Copyright (c) 2010 The FreeBSD Foundation * All rights reserved. * * This software was developed by Lawrence Stewart while studying at the Centre * for Advanced Internet Architectures, Swinburne University of Technology, made * possible in part by a grant from the Cisco University Research Program Fund * at Community Foundation Silicon Valley. * * Portions of this software were developed at the Centre for Advanced * Internet Architectures, Swinburne University of Technology, Melbourne, * Australia by David Hayes under sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD$ */ #ifndef _NETINET_CC_CUBIC_H_ #define _NETINET_CC_CUBIC_H_ #include <sys/limits.h> /* Number of bits of precision for fixed point math calcs. */ #define CUBIC_SHIFT 8 #define CUBIC_SHIFT_4 32 /* 0.5 << CUBIC_SHIFT. */ #define RENO_BETA 128 /* ~0.7 << CUBIC_SHIFT. */ #define CUBIC_BETA 179 /* ~0.3 << CUBIC_SHIFT. */ #define ONE_SUB_CUBIC_BETA 77 /* 3 * ONE_SUB_CUBIC_BETA. */ #define THREE_X_PT3 231 /* (2 << CUBIC_SHIFT) - ONE_SUB_CUBIC_BETA. */ #define TWO_SUB_PT3 435 /* ~0.4 << CUBIC_SHIFT. */ #define CUBIC_C_FACTOR 102 /* CUBIC fast convergence factor: (1+beta_cubic)/2. */ #define CUBIC_FC_FACTOR 217 /* Don't trust s_rtt until this many rtt samples have been taken. */ #define CUBIC_MIN_RTT_SAMPLES 8 /* * (2^21)^3 is long max. Dividing (2^63) by Cubic_C_factor * and taking cube-root yields 448845 as the effective useful limit */ #define CUBED_ROOT_MAX_ULONG 448845 /* Userland only bits. */ #ifndef _KERNEL extern int hz; /* * Implementation based on the formulae found in the CUBIC Internet Draft * "draft-ietf-tcpm-cubic-04". * */ static __inline float theoretical_cubic_k(double wmax_pkts) { double C; C = 0.4; return (pow((wmax_pkts * 0.3) / C, (1.0 / 3.0)) * pow(2, CUBIC_SHIFT)); } static __inline unsigned long theoretical_cubic_cwnd(int ticks_since_cong, unsigned long wmax, uint32_t smss) { double C, wmax_pkts; C = 0.4; wmax_pkts = wmax / (double)smss; return (smss * (wmax_pkts + (C * pow(ticks_since_cong / (double)hz - theoretical_cubic_k(wmax_pkts) / pow(2, CUBIC_SHIFT), 3.0)))); } static __inline unsigned long theoretical_reno_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax, uint32_t smss) { return ((wmax * 0.5) + ((ticks_since_cong / (float)rtt_ticks) * smss)); } static __inline unsigned long theoretical_tf_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax, uint32_t smss) { return ((wmax * 0.7) + ((3 * 0.3) / (2 - 0.3) * (ticks_since_cong / (float)rtt_ticks) * smss)); } #endif /* !_KERNEL */ /* * Compute the CUBIC K value used in the cwnd calculation, using an * implementation of eqn 2 in the I-D. The method used * here is adapted from Apple Computer Technical Report #KT-32. */ static __inline int64_t cubic_k(unsigned long wmax_pkts) { int64_t s, K; uint16_t p; K = s = 0; p = 0; /* (wmax * beta)/C with CUBIC_SHIFT worth of precision. */ s = ((wmax_pkts * ONE_SUB_CUBIC_BETA) << CUBIC_SHIFT) / CUBIC_C_FACTOR; /* Rebase s to be between 1 and 1/8 with a shift of CUBIC_SHIFT. */ while (s >= 256) { s >>= 3; p++; } /* * Some magic constants taken from the Apple TR with appropriate * shifts: 275 == 1.072302 << CUBIC_SHIFT, 98 == 0.3812513 << * CUBIC_SHIFT, 120 == 0.46946116 << CUBIC_SHIFT. */ K = (((s * 275) >> CUBIC_SHIFT) + 98) - (((s * s * 120) >> CUBIC_SHIFT) >> CUBIC_SHIFT); /* Multiply by 2^p to undo the rebasing of s from above. */ return (K <<= p); } /* * Compute the new cwnd value using an implementation of eqn 1 from the I-D. * Thanks to Kip Macy for help debugging this function. * * XXXLAS: Characterise bounds for overflow. */ static __inline unsigned long cubic_cwnd(int ticks_since_cong, unsigned long wmax, uint32_t smss, int64_t K) { int64_t cwnd; /* K is in fixed point form with CUBIC_SHIFT worth of precision. */ /* t - K, with CUBIC_SHIFT worth of precision. */ cwnd = (((int64_t)ticks_since_cong << CUBIC_SHIFT) - (K * hz)) / hz; if (cwnd > CUBED_ROOT_MAX_ULONG) return INT_MAX; if (cwnd < -CUBED_ROOT_MAX_ULONG) return 0; /* (t - K)^3, with CUBIC_SHIFT^3 worth of precision. */ cwnd *= (cwnd * cwnd); /* * C(t - K)^3 + wmax * The down shift by CUBIC_SHIFT_4 is because cwnd has 4 lots of * CUBIC_SHIFT included in the value. 3 from the cubing of cwnd above, * and an extra from multiplying through by CUBIC_C_FACTOR. */ cwnd = ((cwnd * CUBIC_C_FACTOR) >> CUBIC_SHIFT_4) * smss + wmax; /* * for negative cwnd, limiting to zero as lower bound */ return (lmax(0,cwnd)); } /* * Compute an approximation of the NewReno cwnd some number of ticks after a * congestion event. RTT should be the average RTT estimate for the path * measured over the previous congestion epoch and wmax is the value of cwnd at * the last congestion event. The "TCP friendly" concept in the CUBIC I-D is * rather tricky to understand and it turns out this function is not required. * It is left here for reference. */ static __inline unsigned long reno_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax, uint32_t smss) { /* * For NewReno, beta = 0.5, therefore: W_tcp(t) = wmax*0.5 + t/RTT * W_tcp(t) deals with cwnd/wmax in pkts, so because our cwnd is in * bytes, we have to multiply by smss. */ return (((wmax * RENO_BETA) + (((ticks_since_cong * smss) << CUBIC_SHIFT) / rtt_ticks)) >> CUBIC_SHIFT); } /* * Compute an approximation of the "TCP friendly" cwnd some number of ticks * after a congestion event that is designed to yield the same average cwnd as * NewReno while using CUBIC's beta of 0.7. RTT should be the average RTT * estimate for the path measured over the previous congestion epoch and wmax is * the value of cwnd at the last congestion event. */ static __inline unsigned long tf_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax, uint32_t smss) { /* Equation 4 of I-D. */ return (((wmax * CUBIC_BETA) + (((THREE_X_PT3 * (unsigned long)ticks_since_cong * (unsigned long)smss) << CUBIC_SHIFT) / (TWO_SUB_PT3 * rtt_ticks))) >> CUBIC_SHIFT); } #endif /* _NETINET_CC_CUBIC_H_ */
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