On Monday, June 06/27/16, 2016 at 14:51:19 +0530, Eric Dumazet wrote:
> On Mon, 2016-06-27 at 14:29 +0530, Arjun V wrote:
> > On Monday, June 06/27/16, 2016 at 13:36:22 +0530, Eric Dumazet wrote:
> > > On Mon, 2016-06-27 at 12:47 +0530, Arjun V wrote:
> > >
> > > > Eric,
> > > >
> > > > Thanks for the quick patch. It didn't help much. We still see packets
> > > > larger than 65536 with the patch.
> > > >
> > > > Below is the dump_stack() trace I am seeing for packets larger than
> > > > 65536 in our xmit routine:
> > >
> > > What values do you get for skb->len ?
> > >
> > These are the skb->len values I am hitting in t4_eth_xmit() for around half
> > hour run of netperf bidi(800 connections total)
> > packet with skb->len 69570 detected
> > packet with skb->len 66674 detected
>
> Ok please add :
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index
> 5c7ed147449c1b7ba029b12e033ad779a631460a..39bd2a2b8f4d931c514fe62a00541efef29157ad
> 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -845,6 +845,7 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk,
> u32 mss_now,
> {
> struct tcp_sock *tp = tcp_sk(sk);
> u32 new_size_goal, size_goal;
> + u32 res;
>
> if (!large_allowed || !sk_can_gso(sk))
> return mss_now;
> @@ -862,7 +863,11 @@ static unsigned int tcp_xmit_size_goal(struct sock *sk,
> u32 mss_now,
> size_goal = tp->gso_segs * mss_now;
> }
>
> - return max(size_goal, mss_now);
> + res = max(size_goal, mss_now);
> + if (res >= 65536)
> + pr_err_once("tcp_xmit_size_goal() -> %u size_goal %u, mss_now
> %u gso_max_size %u gso_segs %u\n",
> + res, size_goal, mss_now, sk->sk_gso_max_size,
> tp->gso_segs);
> + return res;
> }
>
> static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
>
>
Applied your patch.
The above debug print is not getting invoked, when skb->len is greater than
65536.
