Date: Fri, 30 Nov 2001 12:53:10 -0500 From: John Capo <jc@irbs.com> To: babkin@freebsd.org Cc: jc@irbs.com, freebsd-hackers@freebsd.org Subject: Re: FreeBSD performing worse than Linux? Message-ID: <20011130125310.A3538@exuma.irbs.com> In-Reply-To: <3C0707BD.B8FA31F8@bellatlantic.net>; from babkin@bellatlantic.net on Thu, Nov 29, 2001 at 11:14:53PM -0500 References: <20011128153817.T61580@monorchid.lemis.com> <15364.38174.938500.946169@caddis.yogotech.com> <20011129004234.A16101@exuma.irbs.com> <3C0707BD.B8FA31F8@bellatlantic.net>
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Looking at the complete dump on the server more closely I see what's happening. The server didn't jump ahead in the stream. The client side of these tests is on a fractional T1. In about 60Ms the server pushed a window's worth of data, about 200 packets since the payload was small, 48 bytes. (48 + IP + TCP) * 200 is around 17KB in 60Ms which overflowed the frame switch queue. The other part of the dump where the server is acked for a segment just sent but does not send the next segment till a duplicate ack is received better than a second later is still suspect to me. John Capo Quoting Sergey Babkin (babkin@bellatlantic.net): > > And here a _very_ pathological thing has happened: the server > just forgot to send the data between sequence numbers 12937 > and 28049. Since the dump was done on the server side, this suggests > that something very bad has happened with the TCP state on > the server side. Possibly the value of the current sequence number > in the protocol control block got overwritten by something. > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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