From 17a6e9f1aa9ba07ca13a1eaf1e631e743af50cca Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Mon, 14 Mar 2011 07:52:15 +0000 Subject: [PATCH] tcp_cubic: fix clock dependency 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 Reported-by: Lucas Nussbaum Signed-off-by: David S. Miller --- net/ipv4/tcp_cubic.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c index 66d3b00..f4fb2d4 100644 --- a/net/ipv4/tcp_cubic.c +++ b/net/ipv4/tcp_cubic.c @@ -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 bictcp *ca) 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 bictcp *ca, u32 cwnd) */ /* 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 *sk, u32 delay) 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, u32 cnt, s32 rtt_us) 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; -- 2.7.4