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Merge branch 'tcp-tso'

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Eric Dumazet says:

====================
tcp: tso improvements

This patch serie reworks tcp_tso_should_defer() a bit
to get less bursts, and better ECN behavior.

We also removed tso_deferred field in tcp socket.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2015-02-28 15:10:47 -05:00
commit f9c7ce1853
2 changed files with 17 additions and 13 deletions
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1
include/linux/tcp.h
View File

@ -236,7 +236,6 @@ struct tcp_sock {
u32 lost_out; /* Lost packets */
u32 sacked_out; /* SACK'd packets */
u32 fackets_out; /* FACK'd packets */
u32 tso_deferred;
/* from STCP, retrans queue hinting */
struct sk_buff* lost_skb_hint;

29
net/ipv4/tcp_output.c
View File

@ -1752,20 +1752,23 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
bool *is_cwnd_limited, u32 max_segs)
{
struct tcp_sock *tp = tcp_sk(sk);
const struct inet_connection_sock *icsk = inet_csk(sk);
u32 send_win, cong_win, limit, in_flight;
u32 age, send_win, cong_win, limit, in_flight;
struct tcp_sock *tp = tcp_sk(sk);
struct skb_mstamp now;
struct sk_buff *head;
int win_divisor;
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
goto send_now;
if (icsk->icsk_ca_state != TCP_CA_Open)
if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_CWR)))
goto send_now;
/* Defer for less than two clock ticks. */
if (tp->tso_deferred &&
(((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1)
/* Avoid bursty behavior by allowing defer
* only if the last write was recent.
*/
if ((s32)(tcp_time_stamp - tp->lsndtime) > 0)
goto send_now;
in_flight = tcp_packets_in_flight(tp);
@ -1807,11 +1810,14 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
goto send_now;
}
/* Ok, it looks like it is advisable to defer.
* Do not rearm the timer if already set to not break TCP ACK clocking.
*/
if (!tp->tso_deferred)
tp->tso_deferred = 1 | (jiffies << 1);
head = tcp_write_queue_head(sk);
skb_mstamp_get(&now);
age = skb_mstamp_us_delta(&now, &head->skb_mstamp);
/* If next ACK is likely to come too late (half srtt), do not defer */
if (age < (tp->srtt_us >> 4))
goto send_now;
/* Ok, it looks like it is advisable to defer. */
if (cong_win < send_win && cong_win < skb->len)
*is_cwnd_limited = true;
@ -1819,7 +1825,6 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
return true;
send_now:
tp->tso_deferred = 0;
return false;
}