Date: Wed, 21 Jan 2004 12:16:47 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Andre Oppermann <andre@freebsd.org> Cc: dab@cray.com Subject: Re: tcp mss MCLBYTES restriction Message-ID: <16398.46079.127565.221708@grasshopper.cs.duke.edu> In-Reply-To: <400D9271.1259CBC8@freebsd.org> References: <16397.36782.415899.626311@grasshopper.cs.duke.edu> <400D9271.1259CBC8@freebsd.org>
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Andre Oppermann writes:
>
> Could you run some bechmarks with the current MCLBYTES rounding
> and without it on 100Mbit 1.5kMTU and GigE with 9k MTU?
David Borman is totally right. Clipping the mss is really worth it,
especially with zero-copy sockets. Forget I said anything.
Here is some data I just took.. Send and receiver are 3GHz P4s.
Test is netperf -- -S131072 -s131072. Sender is running current
as of Saturday. Receiver is running 4.9-Release.
"em" is Intel(R) PRO/1000 Network Connection, Version - 1.7.19
"myri" is a M3F2-PCIXE-2. (4Gb/s).
NIC mtu BW %cpu mss_truncate zero_copy
(bytes) (Mb/s)
---- ------ ----- ---- ----- ------
em 16114 727 12.8 0 0
em 16114 730 15.2 1 0
em 16114 728 12.4 0 1
em 16114 743 7.3 1 1
em 9000 870 19.2 0 0
em 9000 900 21.6 1 0
em 9000 867 18.2 0 1
em 9000 845 8.9 1 1
myri 9000 1972 69.0 0 0
myri 9000 2312 68.6 1 0
myri 9000 2609 56.3 0 1
myri 9000 3009 52.3 1 1
Drew
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