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tcp_bbr: introduce bbr_bw_to_pacing_rate() helper 

Introduce a helper to convert a BBR bandwidth and gain factor to a
pacing rate in bytes per second. This is a pure refactor, but is
needed for two following fixes.

Fixes: 0f8782ea14 ("tcp_bbr: add BBR congestion control")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Neal Cardwell 2017-07-14 17:49:22 -04:00 committed by David S. Miller
parent 4aea287e90
commit f19fd62daf
1 changed files with 11 additions and 3 deletions
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14
net/ipv4/tcp_bbr.c
View File

@ -211,6 +211,16 @@ static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
return rate >> BW_SCALE;
}
/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */
static u32 bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
{
u64 rate = bw;
rate = bbr_rate_bytes_per_sec(sk, rate, gain);
rate = min_t(u64, rate, sk->sk_max_pacing_rate);
return rate;
}
/* Pace using current bw estimate and a gain factor. In order to help drive the
* network toward lower queues while maintaining high utilization and low
* latency, the average pacing rate aims to be slightly (~1%) lower than the
@ -220,10 +230,8 @@ static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
*/
static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
{
u64 rate = bw;
u32 rate = bbr_bw_to_pacing_rate(sk, bw, gain);
rate = bbr_rate_bytes_per_sec(sk, rate, gain);
rate = min_t(u64, rate, sk->sk_max_pacing_rate);
if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate)
sk->sk_pacing_rate = rate;
}