mptcp: let MPTCP create max size skbs
Currently the xmit path of the MPTCP protocol creates smaller-
than-max-size skbs, which is suboptimal for the performances.
There are a few things to improve:
- when coalescing to an existing skb, must clear the PUSH flag
- tcp_build_frag() expect the available space as an argument.
When coalescing is enable MPTCP already subtracted the
to-be-coalesced skb len. We must increment said argument
accordingly.
Before:
./use_mptcp.sh netperf -H 127.0.0.1 -t TCP_STREAM
[...]
131072 16384 16384 30.00 24414.86
After:
./use_mptcp.sh netperf -H 127.0.0.1 -t TCP_STREAM
[...]
131072 16384 16384 30.05 28357.69
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index cb8b7ad..b812aaa 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1256,6 +1256,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
struct mptcp_ext *mpext = NULL;
struct sk_buff *skb, *tail;
bool can_collapse = false;
+ int size_bias = 0;
int avail_size;
size_t ret = 0;
@@ -1277,10 +1278,12 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
mpext = skb_ext_find(skb, SKB_EXT_MPTCP);
can_collapse = (info->size_goal - skb->len > 0) &&
mptcp_skb_can_collapse_to(data_seq, skb, mpext);
- if (!can_collapse)
+ if (!can_collapse) {
TCP_SKB_CB(skb)->eor = 1;
- else
+ } else {
+ size_bias = skb->len;
avail_size = info->size_goal - skb->len;
+ }
}
/* Zero window and all data acked? Probe. */
@@ -1300,8 +1303,8 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
return 0;
ret = info->limit - info->sent;
- tail = tcp_build_frag(ssk, avail_size, info->flags, dfrag->page,
- dfrag->offset + info->sent, &ret);
+ tail = tcp_build_frag(ssk, avail_size + size_bias, info->flags,
+ dfrag->page, dfrag->offset + info->sent, &ret);
if (!tail) {
tcp_remove_empty_skb(sk, tcp_write_queue_tail(ssk));
return -ENOMEM;
@@ -1310,8 +1313,9 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
/* if the tail skb is still the cached one, collapsing really happened.
*/
if (skb == tail) {
- WARN_ON_ONCE(!can_collapse);
+ TCP_SKB_CB(tail)->tcp_flags &= ~TCPHDR_PSH;
mpext->data_len += ret;
+ WARN_ON_ONCE(!can_collapse);
WARN_ON_ONCE(zero_window_probe);
goto out;
}
