tcp_bbr: better deal with suboptimal GSO (II)
This is second part of dealing with suboptimal device gso parameters.
In first patch (350c9f484bde "tcp_bbr: better deal with suboptimal GSO")
we dealt with devices having low gso_max_segs
Some devices lower gso_max_size from 64KB to 16 KB (r8152 is an example)
In order to probe an optimal cwnd, we want BBR being not sensitive
to whatever GSO constraint a device can have.
This patch removes tso_segs_goal() CC callback in favor of
min_tso_segs() for CC wanting to override sysctl_tcp_min_tso_segs
Next patch will remove bbr->tso_segs_goal since it does not have
to be persistent.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index a471f69..afc0567 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -261,23 +261,26 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
sk->sk_pacing_rate = rate;
}
-/* Return count of segments we want in the skbs we send, or 0 for default. */
-static u32 bbr_tso_segs_goal(struct sock *sk)
+/* override sysctl_tcp_min_tso_segs */
+static u32 bbr_min_tso_segs(struct sock *sk)
{
- struct bbr *bbr = inet_csk_ca(sk);
-
- return bbr->tso_segs_goal;
+ return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2;
}
static void bbr_set_tso_segs_goal(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
struct bbr *bbr = inet_csk_ca(sk);
- u32 min_segs;
+ u32 segs, bytes;
- min_segs = sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2;
- bbr->tso_segs_goal = min(tcp_tso_autosize(sk, tp->mss_cache, min_segs),
- 0x7FU);
+ /* Sort of tcp_tso_autosize() but ignoring
+ * driver provided sk_gso_max_size.
+ */
+ bytes = min_t(u32, sk->sk_pacing_rate >> sk->sk_pacing_shift,
+ GSO_MAX_SIZE - 1 - MAX_TCP_HEADER);
+ segs = max_t(u32, bytes / tp->mss_cache, bbr_min_tso_segs(sk));
+
+ bbr->tso_segs_goal = min(segs, 0x7FU);
}
/* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */
@@ -936,7 +939,7 @@ static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = {
.undo_cwnd = bbr_undo_cwnd,
.cwnd_event = bbr_cwnd_event,
.ssthresh = bbr_ssthresh,
- .tso_segs_goal = bbr_tso_segs_goal,
+ .min_tso_segs = bbr_min_tso_segs,
.get_info = bbr_get_info,
.set_state = bbr_set_state,
};
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 49d043d..383cac0 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1703,8 +1703,8 @@ static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp,
/* Return how many segs we'd like on a TSO packet,
* to send one TSO packet per ms
*/
-u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
- int min_tso_segs)
+static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
+ int min_tso_segs)
{
u32 bytes, segs;
@@ -1720,7 +1720,6 @@ u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
return segs;
}
-EXPORT_SYMBOL(tcp_tso_autosize);
/* Return the number of segments we want in the skb we are transmitting.
* See if congestion control module wants to decide; otherwise, autosize.
@@ -1728,11 +1727,13 @@ EXPORT_SYMBOL(tcp_tso_autosize);
static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now)
{
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
- u32 tso_segs = ca_ops->tso_segs_goal ? ca_ops->tso_segs_goal(sk) : 0;
+ u32 min_tso, tso_segs;
- if (!tso_segs)
- tso_segs = tcp_tso_autosize(sk, mss_now,
- sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs);
+ min_tso = ca_ops->min_tso_segs ?
+ ca_ops->min_tso_segs(sk) :
+ sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs;
+
+ tso_segs = tcp_tso_autosize(sk, mss_now, min_tso);
return min_t(u32, tso_segs, sk->sk_gso_max_segs);
}