netgear gigabit tuning

Dan Yocum yocum at
Thu Apr 19 12:02:49 PDT 2001

Felix Rauch wrote:
> On Mon, 16 Apr 2001, Chris Black wrote:
> > We have just installed a netgear 4-port copper gigabit switch and are using
> > it with netgear GA620T cards. We are trying to get maximum performance out
> > of this equipment. What I am looking for is tuning instructions for gigabit
> > cards. I have already done:
> > echo 262144 > /proc/sys/net/core/rmem_max
> > echo 262144 > /proc/sys/net/core/wmem_max
> >
> > As directed on the AceNIC driver page. I was unable to get transfers to work
> > when I tried increasing the mtu to 9000 for jumbo frame support though.
> > Right now I get around 39MB/s transfer rate. I am hoping to improve this.
> > What type of numbers do other people with gigabit ethernet setups get?
> It might well be that your reached the maximum performance for your
> processor / memory / CPU / OS setup. With our Hamachi GNIC-II Gigabit
> Ethernet cards we reached about 40 MB/s on 400 MHz/PIII and 2.2.x
> kernels. The same cards achieve over 100 MB/s with our new 1 GHz/PIII
> machines and a linux 2.4.3 kernel.
> AFAIK the 2.4.x kernels have a better TCP/IP stack so you might want
> to check out newer kernel if you are still using 2.2.x.

Those are impressive numbers.  Is this real data from disk or are you
using gensink or ttcp? If you're getting this with real data, what does
you're subsystem look like?  RAID?  What brand/model?  Which
mobo/chipset?  What speed memory?  133MHz?  Make/model?

According to Jes, you really need an SMP machine to get the best
performance out of GigE, at least with the 2.2 kernel.  

Thanks for the info,

Dan Yocum, Sr. Linux Consultant
Linuxcare, Inc.  630.697.8066 tel
yocum at,
Linuxcare. Putting open source to work.

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