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From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	Neal Cardwell <ncardwell@google.com>,
	Yuchung Cheng <ycheng@google.com>
Subject: Re: [PATCH net-next] tcp: add tcp_add_backlog()
Date: Thu, 22 Sep 2016 19:34:11 -0300	[thread overview]
Message-ID: <20160922223411.GA17222@localhost.localdomain> (raw)
In-Reply-To: <1472308674.14381.226.camel@edumazet-glaptop3.roam.corp.google.com>

On Sat, Aug 27, 2016 at 07:37:54AM -0700, Eric Dumazet wrote:
> +bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb)
> +{
> +	u32 limit = sk->sk_rcvbuf + sk->sk_sndbuf;
                                 ^^^
...
> +	if (!skb->data_len)
> +		skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
> +
> +	if (unlikely(sk_add_backlog(sk, skb, limit))) {
...
> -	} else if (unlikely(sk_add_backlog(sk, skb,
> -					   sk->sk_rcvbuf + sk->sk_sndbuf))) {
	                                                 ^---- [1]
> -		bh_unlock_sock(sk);
> -		__NET_INC_STATS(net, LINUX_MIB_TCPBACKLOGDROP);
> +	} else if (tcp_add_backlog(sk, skb)) {

Hi Eric, after this patch, do you think we still need to add sk_sndbuf
as a stretching factor to the backlog here?

It was added by [1] and it was justified that the (s)ack packets were
just too big for the rx buf size. Maybe this new patch alone is enough
already, as such packets will have a very small truesize then.

  Marcelo

[1] da882c1f2eca ("tcp: sk_add_backlog() is too agressive for TCP")

  parent reply	other threads:[~2016-09-22 22:34 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-27 14:37 [PATCH net-next] tcp: add tcp_add_backlog() Eric Dumazet
2016-08-27 16:13 ` Yuchung Cheng
2016-08-27 16:25   ` Eric Dumazet
2016-08-29 16:53     ` Yuchung Cheng
2016-08-27 18:24 ` Neal Cardwell
2016-08-29  4:20 ` David Miller
2016-08-29 18:51 ` Marcelo Ricardo Leitner
2016-08-29 19:22   ` Eric Dumazet
2016-08-29 19:33     ` Marcelo Ricardo Leitner
2016-09-22 22:34 ` Marcelo Ricardo Leitner [this message]
2016-09-22 23:21   ` Eric Dumazet
2016-09-23 12:45     ` Marcelo Ricardo Leitner
2016-09-23 13:42       ` Eric Dumazet
2016-09-23 14:09         ` Marcelo Ricardo Leitner
2016-09-23 14:36           ` Eric Dumazet
2016-09-23 14:43             ` David Laight
2016-09-23 15:12             ` Marcelo Ricardo Leitner

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