Date: Tue, 02 Nov 2004 11:44:15 -0800 From: Julian Elischer <julian@elischer.org> To: Justin Bennett <justin@z-axis.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: ipfw pipes: theoretical speed vs. reality Message-ID: <4187E38F.2070809@elischer.org> In-Reply-To: <4187E23C.7000900@z-axis.com> References: <4187E23C.7000900@z-axis.com>
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Justin Bennett wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > All, > > I have recently been setting up pipes to shape bandwidth on our local > net. > > However, unless I am missing something, the TCP overhead seems quite > large. > > If I configure the following pipe: > > $IPFW pipe 1 config bw 64Kbit/s > $IPFW add 31 pipe 1 ip from 192.168.0.1/24 to any > $IPFW add 32 pipe 1 ip from any to 192.168.0.1/24 > > The run traffic from my machine (192.168.0.2) through it, I get less > than half the expected bandwidth (3.9KB/s). I tried another test with a > 512Kbit/s pipe, and got around 30KB/s. > > I know on most ATM/FR lines, you can expect about 10% overhead, but 50% > seems high. > > When I remove the pipe, my T1 comes back to life, and I can pull the > same data at 160+KB/s. > > Am I missing something? yes you are queuing data in both directions on the same queue, thus serialising it.. use 2 seprarate pipes. one for each direction. > > > Thanks, > > Justin > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.2.5 (MingW32) > > iD8DBQFBh+I8lNUG+Ne1CZMRAl95AJ973J3YiUIStcyJ5c5gM+i2lrebTACfUE83 > 4V9bl8bR9GxjHsKqL764hJk= > =gc51 > -----END PGP SIGNATURE----- > > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to > "freebsd-hackers-unsubscribe@freebsd.org"
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