netdev - Re: [PATCH] Add useful per-connection TCP stats for diagnosis purpose.

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Message-ID: <AANLkTikrJ7A-ygc9JnkvfBpRaKjL0fKeta+9ASLDr0rg@mail.gmail.com>
Date:	Fri, 18 Mar 2011 21:33:45 -0700
From:	Jerry Chu <hkchu@...gle.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Stephen Hemminger <shemminger@...tta.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] Add useful per-connection TCP stats for diagnosis purpose.

On Thu, Mar 17, 2011 at 11:05 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>
> Le jeudi 17 mars 2011 à 21:33 -0700, Jerry Chu a écrit :
>
> > Yes I'm familiar with ss and how inet_csk_diag_fill() calls into
> > tcp_diag_get_info(),..., etc. Like I mentioned previously the netlink
> > interface
> > requires a new version of reader app (e.g., ss) to ship every time a new
> > counter is added and exported by the kernel, whereas /proc/net/tcp does
> > not have such a problem.
> >
> > Anyway I can add a INET_DIAG_INFO_EXT of some sort to netlink in
> > addition to /proc/net/tcp. That's easy to do.
> >
>
> I suggest adding a getsockopt() or something to gather stats for one
> socket. On a loaded machine, /proc/net/tcp is damn slow.

I'm well aware of the past, hideous O(n**2) problem of reading
/proc/net/tcp but I
thought the problem has been fixed by Tom Herbert a while back, no?
(See http://marc.info/?l=linux-netdev&m=127588123429437&w=2)

>
> We have TCP_INFO, we could add TCP_INFO_EXT, but taking care of choosing
> an interface allowing for extension of the structure.

Ok.

Jerry
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