From: Bill Fink <billfink@mindspring•com>
To: Rick Jones <rick.jones2@hp•com>
Cc: Herbert Xu <herbert@gondor•apana.org.au>,
ilpo.jarvinen@helsinki•fi, zbr@ioremap•net,
bert.hubert@netherlabs•nl, h.willstrand@gmail•com,
netdev@vger•kernel.org
Subject: Re: sendfile()? Re: SO_LINGER dead: I get an immediate RST on 2.6.24?
Date: Wed, 14 Jan 2009 03:05:31 -0500 [thread overview]
Message-ID: <20090114030531.a29680c6.billfink@mindspring.com> (raw)
In-Reply-To: <496C3D5C.7080407@hp.com>
On Mon, 12 Jan 2009, Rick Jones wrote:
> Bill Fink wrote:
> > On Tue, 13 Jan 2009, Herbert Xu wrote:
> >
> >
> >>Bill Fink <billfink@mindspring•com> wrote:
> >>
> >>>If I understand you correctly, to hit this corner case, just after
> >>>the final TCP write, there would have to be no packets in flight
> >>>together with a zero TCP window. To make it more bullet-proof, I
> >>>guess after seeing a zero tcpi_unacked, an additional small delay
> >>>should be performed, and then rechecking for a zero tcpi_unacked.
> >>>I don't see anything else obvious (to me anyway) in the tcp_info
> >>>that would be particularly helpful in handling this.
> >>
> >>What's wrong with idiag_wqueue? Isn't that a much more direct
> >>way to get this?
> >
> >
> > I'm not familiar with idiag_wqueue, but it sounds like it has something
> > to do with INET_DIAG/INET_TCP_DIAG. It was a long time ago, but I seem
> > to recall that using INET_DIAG had a negative impact on performance,
> > and since the main point of nuttcp is to measure TCP/UDP performance,
> > that would be contrary to its primary purpose. Also, I don't want to
> > rely on something that's not guaranteed to be part of the running kernel.
>
> How likely is it that the "additional small delay" above would be much
> less than waiting for a read return of zero after a shutdown(SHUT_WR) call?
I'm not sure I understand what you're getting at. I did consider doing
something like what you suggested, but in the end decided it was simpler
to deal with a fully ESTABLISHED connection, than worrying about possible
races with a socket being (partially or fully) closed.
-Bill
next prev parent reply other threads:[~2009-01-14 8:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-13 6:32 sendfile()? Re: SO_LINGER dead: I get an immediate RST on 2.6.24? Herbert Xu
2009-01-13 6:56 ` Bill Fink
2009-01-13 7:01 ` Herbert Xu
2009-01-14 7:43 ` Bill Fink
2009-01-14 8:29 ` Herbert Xu
2009-01-14 9:05 ` Bill Fink
2009-01-14 11:30 ` Herbert Xu
2009-01-15 6:33 ` Bill Fink
2009-01-13 7:06 ` Rick Jones
2009-01-14 8:05 ` Bill Fink [this message]
2009-01-14 8:08 ` Rick Jones
2009-01-14 8:32 ` Bill Fink
-- strict thread matches above, loose matches on Subject: below --
2009-01-11 21:23 bert hubert
2009-01-11 22:08 ` H. Willstrand
2009-01-11 22:45 ` sendfile()? " bert hubert
2009-01-11 22:54 ` Evgeniy Polyakov
2009-01-11 23:08 ` bert hubert
2009-01-11 23:18 ` Evgeniy Polyakov
2009-01-12 4:50 ` Bill Fink
2009-01-12 9:18 ` Ilpo Järvinen
2009-01-13 5:31 ` Bill Fink
2009-02-13 17:02 ` Jeremy Jackson
2009-02-20 18:10 ` Bill Fink
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