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Merge branch 'tcp-minor-adjustments-for-low-pacing-rates'

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Eric Dumazet says:

====================
tcp: minor adjustments for low pacing rates

After pacing horizon addition, we have to adjust how we arm rto
timer, otherwise we might freeze very low pacing rate flows.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2020-05-06 17:29:38 -07:00
commit ee733cd896
3 changed files with 22 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
include/net/tcp.h
View File

@ -1289,26 +1289,22 @@ static inline bool tcp_needs_internal_pacing(const struct sock *sk)
return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
}
/* Return in jiffies the delay before one skb is sent.
* If @skb is NULL, we look at EDT for next packet being sent on the socket.
/* Estimates in how many jiffies next packet for this flow can be sent.
* Scheduling a retransmit timer too early would be silly.
*/
static inline unsigned long tcp_pacing_delay(const struct sock *sk,
const struct sk_buff *skb)
static inline unsigned long tcp_pacing_delay(const struct sock *sk)
{
s64 pacing_delay = skb ? skb->tstamp : tcp_sk(sk)->tcp_wstamp_ns;
s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
pacing_delay -= tcp_sk(sk)->tcp_clock_cache;
return pacing_delay > 0 ? nsecs_to_jiffies(pacing_delay) : 0;
return delay > 0 ? nsecs_to_jiffies(delay) : 0;
}
static inline void tcp_reset_xmit_timer(struct sock *sk,
const int what,
unsigned long when,
const unsigned long max_when,
const struct sk_buff *skb)
const unsigned long max_when)
{
inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk, skb),
inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
max_when);
}
@ -1336,8 +1332,7 @@ static inline void tcp_check_probe_timer(struct sock *sk)
{
if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
tcp_probe0_base(sk), TCP_RTO_MAX,
NULL);
tcp_probe0_base(sk), TCP_RTO_MAX);
}
static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)

4
net/ipv4/tcp_input.c
View File

@ -3014,7 +3014,7 @@ void tcp_rearm_rto(struct sock *sk)
rto = usecs_to_jiffies(max_t(int, delta_us, 1));
}
tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto,
TCP_RTO_MAX, tcp_rtx_queue_head(sk));
TCP_RTO_MAX);
}
}
@ -3291,7 +3291,7 @@ static void tcp_ack_probe(struct sock *sk)
unsigned long when = tcp_probe0_when(sk, TCP_RTO_MAX);
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
when, TCP_RTO_MAX, NULL);
when, TCP_RTO_MAX);
}
}

22
net/ipv4/tcp_output.c
View File

@ -2593,8 +2593,7 @@ bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto)
if (rto_delta_us > 0)
timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us));
tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout,
TCP_RTO_MAX, NULL);
tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX);
return true;
}
@ -3113,6 +3112,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
const struct inet_connection_sock *icsk = inet_csk(sk);
struct sk_buff *skb, *rtx_head, *hole = NULL;
struct tcp_sock *tp = tcp_sk(sk);
bool rearm_timer = false;
u32 max_segs;
int mib_idx;
@ -3135,7 +3135,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
segs = tp->snd_cwnd - tcp_packets_in_flight(tp);
if (segs <= 0)
return;
break;
sacked = TCP_SKB_CB(skb)->sacked;
/* In case tcp_shift_skb_data() have aggregated large skbs,
* we need to make sure not sending too bigs TSO packets
@ -3160,10 +3160,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
continue;
if (tcp_small_queue_check(sk, skb, 1))
return;
break;
if (tcp_retransmit_skb(sk, skb, segs))
return;
break;
NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb));
@ -3172,11 +3172,13 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
if (skb == rtx_head &&
icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT)
tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
inet_csk(sk)->icsk_rto,
TCP_RTO_MAX,
skb);
rearm_timer = true;
}
if (rearm_timer)
tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
inet_csk(sk)->icsk_rto,
TCP_RTO_MAX);
}
/* We allow to exceed memory limits for FIN packets to expedite
@ -3907,7 +3909,7 @@ void tcp_send_probe0(struct sock *sk)
*/
timeout = TCP_RESOURCE_PROBE_INTERVAL;
}
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX, NULL);
tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX);
}
int tcp_rtx_synack(const struct sock *sk, struct request_sock *req)