netdev - Re: [PATCH net-next v6] tcp: Add RFC4898 tcpEStatsPerfDataSegsOut/In

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Message-ID: <20160617213417.GA16126@kafai-mba.local>
Date:	Fri, 17 Jun 2016 14:34:17 -0700
From:	Martin KaFai Lau <kafai@...com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	<netdev@...r.kernel.org>, Kernel Team <kernel-team@...com>,
	Chris Rapier <rapier@....edu>,
	Eric Dumazet <edumazet@...gle.com>,
	Marcelo Ricardo Leitner <mleitner@...hat.com>,
	Neal Cardwell <ncardwell@...gle.com>,
	Yuchung Cheng <ycheng@...gle.com>
Subject: Re: [PATCH net-next v6] tcp: Add RFC4898 tcpEStatsPerfDataSegsOut/In

On Thu, Jun 16, 2016 at 09:30:28PM -0700, Eric Dumazet wrote:
> On Mon, 2016-03-14 at 10:52 -0700, Martin KaFai Lau wrote:
> > Per RFC4898, they count segments sent/received
> > containing a positive length data segment (that includes
> > retransmission segments carrying data).  Unlike
> > tcpi_segs_out/in, tcpi_data_segs_out/in excludes segments
> > carrying no data (e.g. pure ack).
> >
> > The patch also updates the segs_in in tcp_fastopen_add_skb()
> > so that segs_in >= data_segs_in property is kept.
> >
> > Together with retransmission data, tcpi_data_segs_out
> > gives a better signal on the rxmit rate.
> >
> > v6: Rebase on the latest net-next
> >
> > v5: Eric pointed out that checking skb->len is still needed in
> > tcp_fastopen_add_skb() because skb can carry a FIN without data.
> > Hence, instead of open coding segs_in and data_segs_in, tcp_segs_in()
> > helper is used.  Comment is added to the fastopen case to explain why
> > segs_in has to be reset and tcp_segs_in() has to be called before
> > __skb_pull().
> >
> > v4: Add comment to the changes in tcp_fastopen_add_skb()
> > and also add remark on this case in the commit message.
> >
> > v3: Add const modifier to the skb parameter in tcp_segs_in()
> >
> > v2: Rework based on recent fix by Eric:
> > commit a9d99ce28ed3 ("tcp: fix tcpi_segs_in after connection establishment")
> >
> > Signed-off-by: Martin KaFai Lau <kafai@...com>
> > Cc: Chris Rapier <rapier@....edu>
> > Cc: Eric Dumazet <edumazet@...gle.com>
> > Cc: Marcelo Ricardo Leitner <mleitner@...hat.com>
> > Cc: Neal Cardwell <ncardwell@...gle.com>
> > Cc: Yuchung Cheng <ycheng@...gle.com>
> > Acked-by: Eric Dumazet <edumazet@...gle.com>
> > ---
>
> Hi Martin
>
> Have you sent the iproute2 ss corresponding patch ?
Sorry, I did not.  I will work on it shortly.

Thanks for bringing it up!