Date: Thu, 18 Feb 2010 17:04:35 +0100 From: Harald Schmalzbauer <h.schmalzbauer@omnilan.de> To: Stephen Hurd <shurd@sasktel.net> Cc: freebsd-stable@freebsd.org, Patrick Mahan <mahan@mahan.org> Subject: Re: RELENG_8 ignoring TCP window size? [Was: Re: Help for TCP understanding wanted, ACK-MSS-Window [Was: Re: best practice to watch TCP parms of established sockets]] Message-ID: <4B7D6513.6020406@omnilan.de> In-Reply-To: <4B7D645D.3090104@sasktel.net> References: <4B7C1365.9070806@omnilan.de> <70CD649D-7659-4CE2-A16C-49B8C891CB5B@mac.com> <4B7C4066.5040006@omnilan.de> <4B7D3938.1000309@omnilan.de> <4B7D5AC4.9020509@mahan.org> <4B7D61DE.2020906@omnilan.de> <4B7D645D.3090104@sasktel.net>
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[-- Attachment #1 --] Stephen Hurd schrieb am 18.02.2010 17:01 (localtime): > Harald Schmalzbauer wrote: >> Some experimental results: >> When rsyncing with windows, and FreeBSD is receiver, I see the same >> ACK ever two segemnts, but speed is at 72MB/s. >> When FreeBSD is sender and Windows is receiver, it looks more I >> expected. There are about 20 data segments before a ACK is returned. >> And there are TCP Window Update Segments, reflecting smaller receiver >> buffers on the windows side. But this happens at a throughput of >> 82MB/s!!! So the windows machine is behaving like I understand the TCP >> flow control. >> Any explanation why the FreeBSD machine seems to ignore window size? > > IIRC, the delayed ACK RFC requires an ACK at least every second segment. Good hint, but disabling leads to ACK after every single data segment ?!? Thanks, -Harry [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iEYEARECAAYFAkt9ZRQACgkQLDqVQ9VXb8jQtwCfZnCWjfH5hQ92PMd4KgHrZtXZ lzoAnRGFYEg3iwLw7N/PonsMx3hCEXxQ =d8DW -----END PGP SIGNATURE-----
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