[Samba] samba-3.0.24 on openbsd: low throughput

[Jacob Yocom-Piatt]

greetings list. am serving SMB using the samba-3.0.24 package on an 
openbsd 4.1-release machine and am seeing really low throughput from the 
server, even when both the server and client are on gigabit ethernet. 
the maximum throughput i've been able to attain is ~6 MBps, which is 
pretty slow, both on 100 Mbps and 1 Gbps segments. this top speed is 
identical on both 100 Mbps and 1 Gbps.

i've got a default smb.conf file from the package install and have 
attempted modifying a few settings as per suggestions found when 
searching for a solution to this. the only non-default portions are

[global]

   read raw = yes
   write raw = yes
   oplocks = yes
   max xmit = 65535
   dead time = 15
   getwd cache = yes

...

   socket options = IPTOS_LOWDELAY SO_SNDBUF=8192 SO_RCVBUF=8192

without the SO_* options set as above, the throughput is much worse, 
with less than 1 MBps coming through. can pull pretty much full 
linespeed (12 MBps =~ 100 Mbps) using scp from this same server, so it's 
not likely errors on the interface. just to be clear

# netstat -i
Name    Mtu   Network     Address              Ipkts Ierrs    Opkts 
Oerrs Colls
lo0     33192 <Link>                               0     0        0     
0     0
lo0     33192 loopback    localhost.X        0     0        0     0     0
lo0     33192 localhost.s localhost.X        0     0        0     0     0
lo0     33192 fe80::%lo0/ fe80::1%lo0              0     0        0     
0     0
em0     1500  <Link>      00:e0:81:72:7d:05  1859059     2  1872743     
0     0
em0     1500  10.0.0/24   databank.X  1859059     2  1872743     0     0
em0     1500  fe80::%em0/ fe80::2e0:81ff:fe  1859059     2  1872743     
0     0
em1*    1500  <Link>      00:e0:81:72:7d:06        0     0        0     
0     0
pflog0* 33192 <Link>                               0     0        0     
0     0
enc0*   1536  <Link>                               0     0        0     
0     0

any advice or clues on how to get samba to turn out > 6 MBps, or 
preferably > 20 MBps, would be greatly appreciated. do let me know if 
there's any other info that would be good to see.

cheers,
jake

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