| Message ID | 20110314175439.564307922@vyatta.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
Le lundi 14 mars 2011 à 10:52 -0700, Stephen Hemminger a écrit : > pièce jointe document texte brut (tcp-cubic-minrtt.patch) > The hystart code was written with assumption that HZ=1000. > Replace the use of jiffies with bictcp_clock as a millisecond > real time clock. > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> > Reported-by: Lucas Nussbaum <lucas.nussbaum@loria.fr> > > --- a/net/ipv4/tcp_cubic.c 2011-03-14 08:19:18.000000000 -0700 > +++ b/net/ipv4/tcp_cubic.c 2011-03-14 08:22:42.486690594 -0700 > @@ -88,7 +88,7 @@ struct bictcp { > u32 last_time; /* time when updated last_cwnd */ > u32 bic_origin_point;/* origin point of bic function */ > u32 bic_K; /* time to origin point from the beginning of the current epoch */ > - u32 delay_min; /* min delay */ > + u32 delay_min; /* min delay (msec << 3) */ > u32 epoch_start; /* beginning of an epoch */ > u32 ack_cnt; /* number of acks */ > u32 tcp_cwnd; /* estimated tcp cwnd */ > @@ -98,7 +98,7 @@ struct bictcp { > u8 found; /* the exit point is found? */ > u32 round_start; /* beginning of each round */ > u32 end_seq; /* end_seq of the round */ > - u32 last_jiffies; /* last time when the ACK spacing is close */ > + u32 last_ack; /* last time when the ACK spacing is close */ > u32 curr_rtt; /* the minimum rtt of current round */ > }; > > @@ -119,12 +119,21 @@ static inline void bictcp_reset(struct b > ca->found = 0; > } > > +static inline u32 bictcp_clock(void) > +{ > +#if HZ < 1000 > + return ktime_to_ms(ktime_get_real()); Small point : This can be changed if date/time is changed Maybe use monotonic time (aka ktime_get_ts()) ? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 14 Mar 2011 19:51:19 +0100 Eric Dumazet <eric.dumazet@gmail.com> wrote: > Le lundi 14 mars 2011 à 10:52 -0700, Stephen Hemminger a écrit : > > pièce jointe document texte brut (tcp-cubic-minrtt.patch) > > The hystart code was written with assumption that HZ=1000. > > Replace the use of jiffies with bictcp_clock as a millisecond > > real time clock. > > > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> > > Reported-by: Lucas Nussbaum <lucas.nussbaum@loria.fr> > > > > --- a/net/ipv4/tcp_cubic.c 2011-03-14 08:19:18.000000000 -0700 > > +++ b/net/ipv4/tcp_cubic.c 2011-03-14 08:22:42.486690594 -0700 > > @@ -88,7 +88,7 @@ struct bictcp { > > u32 last_time; /* time when updated last_cwnd */ > > u32 bic_origin_point;/* origin point of bic function */ > > u32 bic_K; /* time to origin point from the beginning of the current epoch */ > > - u32 delay_min; /* min delay */ > > + u32 delay_min; /* min delay (msec << 3) */ > > u32 epoch_start; /* beginning of an epoch */ > > u32 ack_cnt; /* number of acks */ > > u32 tcp_cwnd; /* estimated tcp cwnd */ > > @@ -98,7 +98,7 @@ struct bictcp { > > u8 found; /* the exit point is found? */ > > u32 round_start; /* beginning of each round */ > > u32 end_seq; /* end_seq of the round */ > > - u32 last_jiffies; /* last time when the ACK spacing is close */ > > + u32 last_ack; /* last time when the ACK spacing is close */ > > u32 curr_rtt; /* the minimum rtt of current round */ > > }; > > > > @@ -119,12 +119,21 @@ static inline void bictcp_reset(struct b > > ca->found = 0; > > } > > > > +static inline u32 bictcp_clock(void) > > +{ > > +#if HZ < 1000 > > + return ktime_to_ms(ktime_get_real()); > > Small point : This can be changed if date/time is changed > > Maybe use monotonic time (aka ktime_get_ts()) ? I choose get_real() because that is what skb timestamp is using; both should probably use monotonic clock.
Le lundi 14 mars 2011 à 14:21 -0700, Stephen Hemminger a écrit : > I choose get_real() because that is what skb timestamp is using; > both should probably use monotonic clock. > > This point was raised elsewhere, problem is tcpdump/libpcap probably wants "real" time, not monotonic clock... -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/net/ipv4/tcp_cubic.c 2011-03-14 08:19:18.000000000 -0700 +++ b/net/ipv4/tcp_cubic.c 2011-03-14 08:22:42.486690594 -0700 @@ -88,7 +88,7 @@ struct bictcp { u32 last_time; /* time when updated last_cwnd */ u32 bic_origin_point;/* origin point of bic function */ u32 bic_K; /* time to origin point from the beginning of the current epoch */ - u32 delay_min; /* min delay */ + u32 delay_min; /* min delay (msec << 3) */ u32 epoch_start; /* beginning of an epoch */ u32 ack_cnt; /* number of acks */ u32 tcp_cwnd; /* estimated tcp cwnd */ @@ -98,7 +98,7 @@ struct bictcp { u8 found; /* the exit point is found? */ u32 round_start; /* beginning of each round */ u32 end_seq; /* end_seq of the round */ - u32 last_jiffies; /* last time when the ACK spacing is close */ + u32 last_ack; /* last time when the ACK spacing is close */ u32 curr_rtt; /* the minimum rtt of current round */ }; @@ -119,12 +119,21 @@ static inline void bictcp_reset(struct b ca->found = 0; } +static inline u32 bictcp_clock(void) +{ +#if HZ < 1000 + return ktime_to_ms(ktime_get_real()); +#else + return jiffies_to_msecs(jiffies); +#endif +} + static inline void bictcp_hystart_reset(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); struct bictcp *ca = inet_csk_ca(sk); - ca->round_start = ca->last_jiffies = jiffies; + ca->round_start = ca->last_ack = bictcp_clock(); ca->end_seq = tp->snd_nxt; ca->curr_rtt = 0; ca->sample_cnt = 0; @@ -239,8 +248,8 @@ static inline void bictcp_update(struct */ /* change the unit from HZ to bictcp_HZ */ - t = ((tcp_time_stamp + (ca->delay_min>>3) - ca->epoch_start) - << BICTCP_HZ) / HZ; + t = ((tcp_time_stamp + msecs_to_jiffies(ca->delay_min>>3) + - ca->epoch_start) << BICTCP_HZ) / HZ; if (t < ca->bic_K) /* t - K */ offs = ca->bic_K - t; @@ -342,14 +351,12 @@ static void hystart_update(struct sock * struct bictcp *ca = inet_csk_ca(sk); if (!(ca->found & hystart_detect)) { - u32 curr_jiffies = jiffies; + u32 now = bictcp_clock(); /* first detection parameter - ack-train detection */ - if ((s32)(curr_jiffies - ca->last_jiffies) <= - msecs_to_jiffies(hystart_ack_delta)) { - ca->last_jiffies = curr_jiffies; - if ((s32) (curr_jiffies - ca->round_start) > - ca->delay_min >> 4) + if ((s32)(now - ca->last_ack) <= hystart_ack_delta) { + ca->last_ack = now; + if ((s32)(now - ca->round_start) > ca->delay_min >> 4) ca->found |= HYSTART_ACK_TRAIN; } @@ -396,7 +403,7 @@ static void bictcp_acked(struct sock *sk if ((s32)(tcp_time_stamp - ca->epoch_start) < HZ) return; - delay = usecs_to_jiffies(rtt_us) << 3; + delay = (rtt_us << 3) / USEC_PER_MSEC; if (delay == 0) delay = 1;
The hystart code was written with assumption that HZ=1000. Replace the use of jiffies with bictcp_clock as a millisecond real time clock. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Reported-by: Lucas Nussbaum <lucas.nussbaum@loria.fr> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html