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Commit 1b3878ca authored by Neal Cardwell's avatar Neal Cardwell Committed by David S. Miller
Browse files

tcp: export tcp_tso_autosize() and parameterize minimum number of TSO segments 



To allow congestion control modules to use the default TSO auto-sizing
algorithm as one of the ingredients in their own decision about TSO sizing:

1) Export tcp_tso_autosize() so that CC modules can use it.

2) Change tcp_tso_autosize() to allow callers to specify a minimum
   number of segments per TSO skb, in case the congestion control
   module has a different notion of the best floor for TSO skbs for
   the connection right now. For very low-rate paths or policed
   connections it can be appropriate to use smaller TSO skbs.

Signed-off-by: default avatarVan Jacobson <vanj@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarNandita Dukkipati <nanditad@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ed6e7268

include/net/tcp.h

+2 −0
Original line number Diff line number Diff line
@@ -533,6 +533,8 @@ __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 
#endif

/* tcp_output.c */



u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,

		     int min_tso_segs);

void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,

			       int nonagle);

bool tcp_may_send_now(struct sock *sk);

net/ipv4/tcp_output.c

+6 −3
Original line number Diff line number Diff line
@@ -1549,7 +1549,8 @@ 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

 */

static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now)

u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,

		     int min_tso_segs)

{

	u32 bytes, segs;
@@ -1561,10 +1562,11 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now) 
	 * This preserves ACK clocking and is consistent

	 * with tcp_tso_should_defer() heuristic.

	 */

	segs = max_t(u32, bytes / mss_now, sysctl_tcp_min_tso_segs);

	segs = max_t(u32, bytes / mss_now, min_tso_segs);



	return min_t(u32, segs, sk->sk_gso_max_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.
@@ -1574,7 +1576,8 @@ 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;



	return tso_segs ? : tcp_tso_autosize(sk, mss_now);

	return tso_segs ? :

		tcp_tso_autosize(sk, mss_now, sysctl_tcp_min_tso_segs);

}



/* Returns the portion of skb which can be sent right away */