[Samba] Samba - XP performance problem

[David Beck]

Hello There,

After having googled the whole internet for days I decided to go public 
with this issue.
The result of my google queries so far is that there are plenty of 
others with the very same problem I have and noone posted a reasonable 
answer to this:

Using Samba 3 with XP gets bad performance. I tested this on Tru64 5.1b 
and FreeBSD 5.3 with the very same symptoms.
The throughput bw XP and Samba goes up and down. It starts transfering 
with a reasonable speed and after having transfered around 16 megs it 
slows down.
I tried many configuration options regarding locking, tcp settings, xmit 
size and every combination that could make any sense for me.

Then I gave up with this configuration mess as I could lower the 
performnce easily, but the performance jittering was the same.

Now a few notes before I continue: I tested the FreeBSD server on the 
loopback interface and the file write speed was around 43 Megs that is 
close to the disks maximum. I also tested the XP machine with a Windows  
server and the write performnce was around 10 Megs on a 100Mbit link. In 
addition to that the FreeBSD machine is at my home and the Tru64 and the 
Windows server are where I work. I'm pretty sure that this is not a 
network issue.

After spending a lot of time with investigation I decided to go deeper 
in this issue. I installed ethereal to capture the traffic and compare 
the results bw XP-Windows and XP-Tru64. The test was to copy 50Meg file 
to both servers and capture the packets. To my surprise the conversation 
was quite different.

XP-Windows (excerpt):
- nt create and x
- trans2: query file info internal
- set file info
- tcp data stream...

XP-Samba (excerpt):
- nt create and x
- trans2: query file info internal
- (query file info + write and x request) many times, incresing offset, 
one byte length
- tcp data stream....

In case of XP-Samba, the last two steps are repeated many times.
Large part of the effective bandwith is filled with query file info and 
1 byte writes.

The packet data can be downloaded from these links:

http://dbeck.beckground.hu/download/xp-samba.bz2
http://dbeck.beckground.hu/download/xp-win.bz2

I also made a screenshot of a bandwith monitor to show what I mean by 
performance jittering:

http://dbeck.beckground.hu/download/samba-performance-write.PNG
http://dbeck.beckground.hu/download/samba-performance-read.PNG

Please note that the original packet log for the 50 Meg file was very 
large, so I kept only the interesting parts.

Last, could anyone there, Samba and SMB wizards help me, how to solve 
this performance issue?

Thank you in advance,

David.