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[TCP]: congestion control API pass RTT in microseconds

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This patch changes the API for the callback that is done after an ACK is
received. It solves a couple of issues:

  * Some congestion controls want higher resolution value of RTT
    (controlled by TCP_CONG_RTT_SAMPLE flag). These don't really want a ktime, but
    all compute a RTT in microseconds.

  * Other congestion control could use RTT at jiffies resolution.

To keep API consistent the units should be the same for both cases, just the
resolution should change.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger
2007-07-25 23:49:34 -07:00
committed by David S. Miller
parent 6a302358d8
commit 30cfd0baf0
12 changed files with 39 additions and 29 deletions
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8
net/ipv4/tcp_illinois.c
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@@ -83,18 +83,16 @@ static void tcp_illinois_init(struct sock *sk)
}
/* Measure RTT for each ack. */
static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, ktime_t last)
static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, s32 rtt)
{
struct illinois *ca = inet_csk_ca(sk);
u32 rtt;
ca->acked = pkts_acked;
if (ktime_equal(last, net_invalid_timestamp()))
/* dup ack, no rtt sample */
if (rtt < 0)
return;
rtt = ktime_to_us(net_timedelta(last));
/* ignore bogus values, this prevents wraparound in alpha math */
if (rtt > RTT_MAX)
rtt = RTT_MAX;