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cc_cubic:

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- Update cubic parameters to draft-ietf-tcpm-cubic-04

Submitted by:	Matt Macy <mmacy@mattmacy.io>
Reviewed by:	lstewart
Differential Revision:	https://reviews.freebsd.org/D10556
This commit is contained in:
sbruno 2018-05-03 15:01:27 +00:00
parent fa18a0cf9f
commit 8bb5c83353
1 changed files with 14 additions and 15 deletions
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29
sys/netinet/cc/cc_cubic.h
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@ -51,23 +51,23 @@
/* 0.5 << CUBIC_SHIFT. */
#define RENO_BETA 128
/* ~0.8 << CUBIC_SHIFT. */
#define CUBIC_BETA 204
/* ~0.7 << CUBIC_SHIFT. */
#define CUBIC_BETA 179
/* ~0.2 << CUBIC_SHIFT. */
#define ONE_SUB_CUBIC_BETA 51
/* ~0.3 << CUBIC_SHIFT. */
#define ONE_SUB_CUBIC_BETA 77
/* 3 * ONE_SUB_CUBIC_BETA. */
#define THREE_X_PT2 153
#define THREE_X_PT3 231
/* (2 << CUBIC_SHIFT) - ONE_SUB_CUBIC_BETA. */
#define TWO_SUB_PT2 461
#define TWO_SUB_PT3 435
/* ~0.4 << CUBIC_SHIFT. */
#define CUBIC_C_FACTOR 102
/* CUBIC fast convergence factor: ~0.9 << CUBIC_SHIFT. */
#define CUBIC_FC_FACTOR 230
/* 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
@ -79,9 +79,8 @@ extern int hz;
/*
* Implementation based on the formulae found in the CUBIC Internet Draft
* "draft-rhee-tcpm-cubic-02".
* "draft-ietf-tcpm-cubic-04".
*
* Note BETA used in cc_cubic is equal to (1-beta) in the I-D
*/
static __inline float
@ -91,7 +90,7 @@ theoretical_cubic_k(double wmax_pkts)
C = 0.4;
return (pow((wmax_pkts * 0.2) / C, (1.0 / 3.0)) * pow(2, CUBIC_SHIFT));
return (pow((wmax_pkts * 0.3) / C, (1.0 / 3.0)) * pow(2, CUBIC_SHIFT));
}
static __inline unsigned long
@ -120,7 +119,7 @@ theoretical_tf_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax,
uint32_t smss)
{
return ((wmax * 0.8) + ((3 * 0.2) / (2 - 0.2) *
return ((wmax * 0.7) + ((3 * 0.3) / (2 - 0.3) *
(ticks_since_cong / (float)rtt_ticks) * smss));
}
@ -232,7 +231,7 @@ reno_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax,
/*
* 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 0.8. RTT should be the average RTT
* 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.
*/
@ -242,8 +241,8 @@ tf_cwnd(int ticks_since_cong, int rtt_ticks, unsigned long wmax,
{
/* Equation 4 of I-D. */
return (((wmax * CUBIC_BETA) + (((THREE_X_PT2 * ticks_since_cong *
smss) << CUBIC_SHIFT) / TWO_SUB_PT2 / rtt_ticks)) >> CUBIC_SHIFT);
return (((wmax * CUBIC_BETA) + (((THREE_X_PT3 * ticks_since_cong *
smss) << CUBIC_SHIFT) / TWO_SUB_PT3 / rtt_ticks)) >> CUBIC_SHIFT);
}
#endif /* _NETINET_CC_CUBIC_H_ */