On Sat, 2017-10-14 at 13:47 +0200, Natale Patriciello wrote:
> Usually, the pacing time is provided per-segment. In some occasion, this
> time refers to the time between a group of segments. With this commit, add
> the possibility for the congestion control module to tell the TCP socket
> how many segments can be sent out before pausing and setting a pacing
> timer.
>
> Signed-off-by: Natale Patriciello <natale.patricie...@gmail.com>
> ---
> include/net/tcp.h | 2 ++
> net/ipv4/tcp_output.c | 13 +++++++++----
> 2 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index e817f0669d0e..3561eca5a61f 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -1019,6 +1019,8 @@ struct tcp_congestion_ops {
> u64 (*get_pacing_time)(struct sock *sk);
> /* the pacing timer is expired (optional) */
> void (*pacing_timer_expired)(struct sock *sk);
> + /* get the # segs to send out when the timer expires (optional) */
> + u32 (*get_segs_per_round)(struct sock *sk);
>
> char name[TCP_CA_NAME_MAX];
> struct module *owner;
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 25b4cf0802f2..e37941e4328b 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -2249,6 +2249,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned
> int mss_now, int nonagle,
> int result;
> bool is_cwnd_limited = false, is_rwnd_limited = false;
> u32 max_segs;
> + u32 pacing_allowed_segs = 0;
>
> sent_pkts = 0;
>
> @@ -2265,14 +2266,18 @@ static bool tcp_write_xmit(struct sock *sk, unsigned
> int mss_now, int nonagle,
> max_segs = tcp_tso_segs(sk, mss_now);
> tcp_mstamp_refresh(tp);
>
> - if (!tcp_pacing_timer_check(sk) &&
> - ca_ops && ca_ops->pacing_timer_expired)
> - ca_ops->pacing_timer_expired(sk);
> + if (!tcp_pacing_timer_check(sk)) {
> + pacing_allowed_segs = 1;
> + if (ca_ops && ca_ops->pacing_timer_expired)
> + ca_ops->pacing_timer_expired(sk);
> + if (ca_ops && ca_ops->get_segs_per_round)
> + pacing_allowed_segs = ca_ops->get_segs_per_round(sk);
> + }
>
> while ((skb = tcp_send_head(sk))) {
> unsigned int limit;
>
> - if (tcp_pacing_check(sk))
> + if (sent_pkts >= pacing_allowed_segs)
> break;
>
So, if pacing_allowed_segs == 0, we break immediately of the loop ????
Are you sure you have tested this patch with normal CC like CUBIC and
BBR ?
