netdev - Re: [REGRESSION, bisect]cxgb4 port failure with TSO traffic after commit 10d3be569243def8("tcp-tso: do not split TSO packets at retransmit time")

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Date:	Mon, 27 Jun 2016 19:43:40 +0530
From:	Arjun V <arjun@...lsio.com>
To:	Neal Cardwell <ncardwell@...gle.com>,
	Eric Dumazet <edumazet@...gle.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Hariprasad S <hariprasad@...lsio.com>,
	Casey Leedom <leedom@...lsio.com>,
	Kumar A S <kumaras@...lsio.com>,
	Santosh Rastapur <santosh@...lsio.com>,
	Nirranjan Kirubaharan <nirranjan@...lsio.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"ycheng@...gle.com" <ycheng@...gle.com>
Subject: Re: [REGRESSION, bisect]cxgb4 port failure with TSO traffic after
 commit 10d3be569243def8("tcp-tso: do not split TSO packets at retransmit
 time")

On Monday, June 06/27/16, 2016 at 19:06:05 +0530, Neal Cardwell wrote:
> On Mon, Jun 27, 2016 at 9:27 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> > Excellent idea ;)
> >
> > Here is the v2 patch.
> >
> > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> > index 8bd9911fdd16..e00e972c4e6a 100644
> > --- a/net/ipv4/tcp_output.c
> > +++ b/net/ipv4/tcp_output.c
> > @@ -2751,7 +2751,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
> >         struct tcp_sock *tp = tcp_sk(sk);
> >         struct sk_buff *skb;
> >         struct sk_buff *hole = NULL;
> > -       u32 last_lost;
> > +       u32 max_segs, last_lost;
> >         int mib_idx;
> >         int fwd_rexmitting = 0;
> >
> > @@ -2771,6 +2771,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
> >                 last_lost = tp->snd_una;
> >         }
> >
> > +       max_segs = tcp_tso_autosize(sk, tcp_current_mss(sk));
> >         tcp_for_write_queue_from(skb, sk) {
> >                 __u8 sacked = TCP_SKB_CB(skb)->sacked;
> >                 int segs;
> > @@ -2784,6 +2785,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
> >                 segs = tp->snd_cwnd - tcp_packets_in_flight(tp);
> >                 if (segs <= 0)
> >                         return;
> > +               /* In case tcp_shift_skb_data() have aggregated large skbs,
> > +                * we need to make sure not sending too big TSO packets.
> > +                */
> > +               segs = min_t(int, segs, max_segs);
> >
> >                 if (fwd_rexmitting) {
> >  begin_fwd:
> >
> 
> Looks great to me. Thanks, Eric!
> 
> neal

This patch works fine. Now I am not seeing any packets with len > 64K. Thanks Eric for your support.

Arjun.