diff options
Diffstat (limited to 'sys/netinet/tcp_var.h')
| -rw-r--r-- | sys/netinet/tcp_var.h | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h index d53251a0..3035143 100644 --- a/sys/netinet/tcp_var.h +++ b/sys/netinet/tcp_var.h @@ -31,7 +31,7 @@ * SUCH DAMAGE. * * @(#)tcp_var.h 8.4 (Berkeley) 5/24/95 - * $Id: tcp_var.h,v 1.29 1996/02/26 21:47:13 guido Exp $ + * $Id: tcp_var.h,v 1.30 1996/02/27 15:12:53 bde Exp $ */ #ifndef _NETINET_TCP_VAR_H_ @@ -191,10 +191,18 @@ struct rmxp_tao { * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the * binary point, and is smoothed with an ALPHA of 0.75. */ +#ifdef notdef #define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */ #define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */ #define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */ #define TCP_RTTVAR_SHIFT 2 /* shift for rttvar; 2 bits */ +#else +#define TCP_RTT_SCALE 32 /* multiplier for srtt; 3 bits frac. */ +#define TCP_RTT_SHIFT 5 /* shift for srtt; 3 bits frac. */ +#define TCP_RTTVAR_SCALE 16 /* multiplier for rttvar; 2 bits */ +#define TCP_RTTVAR_SHIFT 4 /* shift for rttvar; 2 bits */ +#define TCP_DELTA_SHIFT 2 /* see tcp_input.c */ +#endif /* * The initial retransmission should happen at rtt + 4 * rttvar. @@ -206,11 +214,25 @@ struct rmxp_tao { * 1.5 tick we need. But, because the bias is * statistical, we have to test that we don't drop below * the minimum feasible timer (which is 2 ticks). +#ifdef notdef * This macro assumes that the value of TCP_RTTVAR_SCALE * is the same as the multiplier for rttvar. +#else + * This version of the macro adapted from a paper by Lawrence + * Brakmo and Larry Peterson which outlines a problem caused + * by insufficient precision in the original implementation, + * which results in inappropriately large RTO values for very + * fast networks. +#endif */ +#ifdef notdef #define TCP_REXMTVAL(tp) \ (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar) +#else +#define TCP_REXMTVAL(tp) \ + ((((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT)) \ + + ((tp)->t_rttvar) >> TCP_RTTVAR_SHIFT)) +#endif /* XXX * We want to avoid doing m_pullup on incoming packets but that |
