FreeBSD 5.4 network performance with SMP
Matt Hartzell
mchartzell at getdts.com
Sun Oct 2 15:47:31 PDT 2005
In my experience I had to disable the USB in the bios.
Do a quick vmstat -i and note how many interrupts are on the uhci
device - with no devices even connected to the usb bus.
Also, what sysctl settings are you using?
If your network supports it, how about using jumbo frames?
Robert Lindgren wrote:
>Hi All,
>
>I have a strange little problem on Dell 1800's. If HT,SMP is enabled in the
>kernel (5.4p7), performance on the integrated em0 is not especially good,
>half the speed of the current 100Mbit connection. This is true from the
>server and a little better to the server. On a pci rl0 card in the same
>machine performance is even worse. About 15Mbit from the server!
>
>Then I read a lot of people having poor performance from the rl0 cards and a
>lot of FreeBSD people bashing it for being crap, even in the source code for
>the module it's stated that these cards aren't so good. I guess that is right
>to some extent but not 15Mbit/sec.
>
>So when I rebuilt the kernel without HT and SMP I get full wirespeed from the
>em0 and the rl0 (100Mbit/sec). Is there anything I've been doing wrong to get
>hit by this poor performance with the SMP kernel. I read the disabling USB
>could improve performance but tried that with the HT kernel without any luck.
>
>The server has 1 3Ghz cpu, and I would prefer too run a HT enabled kernel, but
>not with that kind of performance, so please advice. The same machines (Dell
>1800) run linux with HT enabled without any network performance degradation.
>
>Best regards
>Robert Lindgren
>
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>
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