From 1485348d2424e1131ea42efc033cbd9366462b01 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Mon, 30 Jul 2012 16:11:42 +0000 Subject: [PATCH] tcp: Apply device TSO segment limit earlier Cache the device gso_max_segs in sock::sk_gso_max_segs and use it to limit the size of TSO skbs. This avoids the need to fall back to software GSO for local TCP senders. Signed-off-by: Ben Hutchings Signed-off-by: David S. Miller --- include/net/sock.h | 2 ++ net/core/sock.c | 1 + net/ipv4/tcp.c | 4 +++- net/ipv4/tcp_cong.c | 3 ++- net/ipv4/tcp_output.c | 21 ++++++++++++--------- 5 files changed, 20 insertions(+), 11 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index b373023..72132ae 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -218,6 +218,7 @@ struct cg_proto; * @sk_route_nocaps: forbidden route capabilities (e.g NETIF_F_GSO_MASK) * @sk_gso_type: GSO type (e.g. %SKB_GSO_TCPV4) * @sk_gso_max_size: Maximum GSO segment size to build + * @sk_gso_max_segs: Maximum number of GSO segments * @sk_lingertime: %SO_LINGER l_linger setting * @sk_backlog: always used with the per-socket spinlock held * @sk_callback_lock: used with the callbacks in the end of this struct @@ -338,6 +339,7 @@ struct sock { netdev_features_t sk_route_nocaps; int sk_gso_type; unsigned int sk_gso_max_size; + u16 sk_gso_max_segs; int sk_rcvlowat; unsigned long sk_lingertime; struct sk_buff_head sk_error_queue; diff --git a/net/core/sock.c b/net/core/sock.c index 6b654b3..8f67ced 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1458,6 +1458,7 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) } else { sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM; sk->sk_gso_max_size = dst->dev->gso_max_size; + sk->sk_gso_max_segs = dst->dev->gso_max_segs; } } } diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index e7e6eea..2109ff4 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -811,7 +811,9 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now, old_size_goal + mss_now > xmit_size_goal)) { xmit_size_goal = old_size_goal; } else { - tp->xmit_size_goal_segs = xmit_size_goal / mss_now; + tp->xmit_size_goal_segs = + min_t(u16, xmit_size_goal / mss_now, + sk->sk_gso_max_segs); xmit_size_goal = tp->xmit_size_goal_segs * mss_now; } } diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 4d4db16..1432cdb 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -291,7 +291,8 @@ bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight) left = tp->snd_cwnd - in_flight; if (sk_can_gso(sk) && left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd && - left * tp->mss_cache < sk->sk_gso_max_size) + left * tp->mss_cache < sk->sk_gso_max_size && + left < sk->sk_gso_max_segs) return true; return left <= tcp_max_tso_deferred_mss(tp); } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 3f1bcff..a7b3ec9 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1522,21 +1522,21 @@ static void tcp_cwnd_validate(struct sock *sk) * when we would be allowed to send the split-due-to-Nagle skb fully. */ static unsigned int tcp_mss_split_point(const struct sock *sk, const struct sk_buff *skb, - unsigned int mss_now, unsigned int cwnd) + unsigned int mss_now, unsigned int max_segs) { const struct tcp_sock *tp = tcp_sk(sk); - u32 needed, window, cwnd_len; + u32 needed, window, max_len; window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; - cwnd_len = mss_now * cwnd; + max_len = mss_now * max_segs; - if (likely(cwnd_len <= window && skb != tcp_write_queue_tail(sk))) - return cwnd_len; + if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) + return max_len; needed = min(skb->len, window); - if (cwnd_len <= needed) - return cwnd_len; + if (max_len <= needed) + return max_len; return needed - needed % mss_now; } @@ -1765,7 +1765,8 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) limit = min(send_win, cong_win); /* If a full-sized TSO skb can be sent, do it. */ - if (limit >= sk->sk_gso_max_size) + if (limit >= min_t(unsigned int, sk->sk_gso_max_size, + sk->sk_gso_max_segs * tp->mss_cache)) goto send_now; /* Middle in queue won't get any more data, full sendable already? */ @@ -1999,7 +2000,9 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, limit = mss_now; if (tso_segs > 1 && !tcp_urg_mode(tp)) limit = tcp_mss_split_point(sk, skb, mss_now, - cwnd_quota); + min_t(unsigned int, + cwnd_quota, + sk->sk_gso_max_segs)); if (skb->len > limit && unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) -- 1.7.7.6