diff options
| author | Daniel Borkmann <dborkman@redhat.com> | 2013-06-19 12:51:20 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-06-19 21:16:53 -0700 |
| commit | eea86af6b1e18d6fa8dc959e3ddc0100f27aff9f (patch) | |
| tree | a8f200392d1671a058311009aa360226c22b5da8 | |
| parent | dc25c676f54addb10e598daa9da9b8dd4fd487ab (diff) | |
net: sock: adapt SOCK_MIN_RCVBUF and SOCK_MIN_SNDBUF
The current situation is that SOCK_MIN_RCVBUF is 2048 + sizeof(struct sk_buff))
while SOCK_MIN_SNDBUF is 2048. Since in both cases, skb->truesize is used for
sk_{r,w}mem_alloc accounting, we should have both sizes adjusted via defining a
TCP_SKB_MIN_TRUESIZE.
Further, as Eric Dumazet points out, the minimal skb truesize in transmit path is
SKB_TRUESIZE(2048) after commit f07d960df33c5 ("tcp: avoid frag allocation for
small frames"), and tcp_sendmsg() tries to limit skb size to half the congestion
window, meaning we try to build two skbs at minimum. Thus, having SOCK_MIN_SNDBUF
as 2048 can hit a small regression for some applications setting to low
SO_SNDBUF / SO_RCVBUF. Note that we define a TCP_SKB_MIN_TRUESIZE, because
SKB_TRUESIZE(2048) adds SKB_DATA_ALIGN(sizeof(struct skb_shared_info)), but in
case of TCP skbs, the skb_shared_info is part of the 2048 bytes allocation for
skb->head.
The minor adaption in sk_stream_moderate_sndbuf() is to silence a warning by
using a typed max macro, as similarly done in SOCK_MIN_RCVBUF occurences, that
would appear otherwise.
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/sock.h | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/include/net/sock.h b/include/net/sock.h index 21db792bffa5..ea6206ccc896 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2047,18 +2047,21 @@ static inline void sk_wake_async(struct sock *sk, int how, int band) sock_wake_async(sk->sk_socket, how, band); } -#define SOCK_MIN_SNDBUF 2048 -/* - * Since sk_rmem_alloc sums skb->truesize, even a small frame might need - * sizeof(sk_buff) + MTU + padding, unless net driver perform copybreak +/* Since sk_{r,w}mem_alloc sums skb->truesize, even a small frame might + * need sizeof(sk_buff) + MTU + padding, unless net driver perform copybreak. + * Note: for send buffers, TCP works better if we can build two skbs at + * minimum. */ -#define SOCK_MIN_RCVBUF (2048 + sizeof(struct sk_buff)) +#define TCP_SKB_MIN_TRUESIZE (2048 + sizeof(struct sk_buff)) + +#define SOCK_MIN_SNDBUF (TCP_SKB_MIN_TRUESIZE * 2) +#define SOCK_MIN_RCVBUF TCP_SKB_MIN_TRUESIZE static inline void sk_stream_moderate_sndbuf(struct sock *sk) { if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK)) { sk->sk_sndbuf = min(sk->sk_sndbuf, sk->sk_wmem_queued >> 1); - sk->sk_sndbuf = max(sk->sk_sndbuf, SOCK_MIN_SNDBUF); + sk->sk_sndbuf = max_t(u32, sk->sk_sndbuf, SOCK_MIN_SNDBUF); } } |