[Samba] performance on small files transfers

[kxsq]

Hi all,
  I'm confused of small files (no bigger than 50k ) 
transfers speed through samba,which is very slow on 
my machine. Bellow is a real case,

-- SuSE professional 9.2, kernel 2.6.11,Samba 3.0.14a,reiserfs 
-- Dual AMD Opteron,4G mem,Giga byte LAN
-- 2 raid 5 make up of 16 SATA hard disks
-- set readhead to 1024 

I tested raids speed using bonnie++ and get 450 Mbytes/s 
at 16GB files measure.So I believe the raid is not the 
bottleneck.I wrote a script to get 200,000 small files no 
more than 50K,totally size 8G.When I wrote these small 
files to SAMBA server and get a speed about 1.5 Mbyte/s.
And the speed hit 8 Mbytes/s when these small files
copied from one raid to another locally. 

There must be misconfigured somewhere,but I don't where.
Can anybody give me some tips?