[Samba] samba 3 performance issues

[Rohit Kumar Mehta]

I believe I have some hardware related performance issues running samba 
3.0.14a-3sarge.

Our server is an Intel Celeron 2 Ghz with 512 MB of RAM and a 3ware
card using SATA disks in a RAID 5 configuration (3ware controller card). 
  We have a gigabit network and are using Intel Gigabit ethernet cards 
e1000).

When copying large files to the samba shares on the system, the transfer
rate maxes out near 100 mb/s.  We tested with nttcp and were able to get
speeds of nearly 800mb/s.  So I think it is safe to conclude this is a 
software issue and not a network issue.

So running top while doing this large copy, showed that smbd was the top
process chewing on >80% of the CPU.  Kill the copy, and the cpu idle 
time exceeds 90%.  We are convinced that our CPU is the bottleneck,
but not sure why.

#cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) Celeron(R) CPU 2.00GHz
stepping        : 9
cpu MHz         : 1996.920
cache size      : 128 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge 
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid
bogomips        : 3956.73

Does anyone have any advice on how to speed up our file transfers? We 
regularly have to 18 GB worth of files to this system, and it would be 
very good if we could speed it up.  At current speeds, we get no 
advantage from even having gigabit network cards!

Please feel free to ask me any other questions about our system setup. 
Thanks in advance for any advice,

Rohit