On Wed, Apr 20, 2016 at 04:04:54PM -0400, Soheil Hassas Yeganeh wrote:
> > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> > index a6e4a83..96bdf98 100644
> > --- a/net/ipv4/tcp_output.c
> > +++ b/net/ipv4/tcp_output.c
> > @@ -2494,6 +2494,7 @@ static void tcp_collapse_retrans(struct sock *sk,
> > struct sk_buff *skb)
> > * packet counting does not break.
> > */
> > TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked &
> > TCPCB_EVER_RETRANS;
> > + TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor;
> >
> > /* changed transmit queue under us so clear hints */
> > tcp_clear_retrans_hints_partial(tp);
> > @@ -2545,6 +2546,9 @@ static void tcp_retrans_try_collapse(struct sock *sk,
> > struct sk_buff *to,
> > if (!tcp_can_collapse(sk, skb))
> > break;
> >
> > + if (TCP_SKB_CB(to)->eor)
> > + break;
> > +
>
> nit: Perhaps a better place to check for eor is right after entering
> the loop? to skip a few instructions and tcp_can_collapse, in an
> unlikely case eor is set.
hmm... Not sure I understand it.
You meant moving the unlikely case before (or after?) the more likely
cases which may have a better chance to break the loop sooner?
