[OpenAFS] about openafs , fileserver process , performance

[nicolas prochazka]

Hello,
I need some help to customize my openafs server.

fileserver process is starting with :
 /usr/libexec/openafs/fileserver -jumbo -L -sendsize 512000 -b 6000 -p
128 -l 15000 -s 50000 -vc 1000 -cb 8000000 -rxpck 3600 -udpsize
12582912 -busyat 1200 -vattachpar 4

Version :
openafs 1.6.6
linux 3.11

Openafs server, serve big file ( 5Go )

I do some benchmark ,
cat /afs/mycell.com/bigfile > /dev/null   on openafs clients
and i see a bottleneck of 25MBytes/s  on server side ( fileserver process) .
My ethernet link are 1Gbit/s

How can I suppress this bottleneck ?

Regards,
Nicolas Prochazka.